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The VST LAB Coffee III is the gold standard for coffee refractometers among coffee professionals. It is accurate. It is consistent. It is durable.
It is not cheap.
We’re going to tell you more about the VST refractometer in this post, but you may be wondering whether there’s something a little more affordable that can do the job.
The Atago PAL is the next best coffee refractometer. If you decide to move down to that price point—which is still quite substantial—we’ll explain what you might be giving up.
And finally, we’ll take a look at a newer coffee refractometer that is much more affordable and might just be enough for the home enthusiast who has no professional aspirations.
Things To Consider Before Buying a Coffee Refractometer
Coffee refractometers are scientific tools that allow coffee professionals and enthusiasts to modify their brewing processes based on data. A refractometer gives you information about the quality of your coffee—in particular, it measures the total dissolved solids (TDS) in your brew.
This is basically the percentage of your cup that isn’t water.
When you know this, and you know how much coffee and water you started with, then you know how efficiently your brewing process has extracted from the coffee beans.
Here are a few factors you should take into account when shopping for a coffee refractometer.
Quality and Durability
Quality and durability are two things that distinguish the best coffee refractometers. You want your instrument to last you for years, especially if you’re spending significant money. Consider the materials used to manufacture it and make sure they are of high quality.
To make your ideal cup of coffee, you need the gadget to give you accurate and precise measurements, and you need those measurements to be consistent.
A refractometer only needs to be consistent with itself. You don’t have to worry if one refractometer gives a slightly different reading from another. You don’t have to decide which one to believe. All that matters is that the same refractometer gives consistent readings for the same coffee, over and over again.
The reason for this is that you will be using the refractometer to compare cups of coffee, so you can improve them. The absolute numbers it gives you are far less important than the change in those numbers from cup to cup, as you tweak your brewing method.
When considering a model’s performance, look through reviews posted by previous customers to get a better understanding of how it performs. Do they have grievances that you find unacceptable? Doing a little bit of this homework increases your chances of finding the product that will suit you.
Ease of Use
It certainly helps to have a refractometer that’s simple to operate. You should consider the product’s design for this. An easy and user-friendly interface is an asset.
Make sure you have a solid idea of how these coffee tools function if this will be your first time using one. A good refractometer should come with an easy-to-understand user manual.
Most of these devices are fairly portable, but they can vary in size. Think about how easy it will be to transport if you plan to use it in multiple locations, like your home and a coffee shop.
TheDiFluid refractometer, the least expensive of the devices we’ll be reviewing, is quite small and fit for transport:
High-quality goods cost more than average goods. And if we’re being honest, most coffee professionals will tell you that an inexpensive coffee refractometer is a waste of time.
“This isn’t a tool you can compromise on,” said one Reddit user. “You either buy an Atago, a VST, or nothing. Anything less is going to do more harm than good to your understanding of extraction.”
Refractometers are, by their very nature, for serious fine-tuning. So having one that kind of works isn’t much use.
Having said that, we think the more affordable model that we’ll be covering is acceptable for the non-professional.
Types of Coffee Refractometers
You have a variety of choices. However, most coffee refractometers are either digital or optical.
Digital Coffee Refractometers
The digital coffee refractometer, like the Atago PAL pictured above, is the most popular tool baristas use to measure TDS. In general, digital coffee refractometers are capable of more than just TDS measurement. For instance, most models can also determine how much sugar is in your coffee.
Optical Coffee Refractometers
Optical coffee refractometers are usually smaller than their digital counterparts (think about a larger-than-normal thermometer) and tend to be cheaper.
An optical coffee refractometer doesn’t measure TDS—it only measures sugar content. This is expressed in a measure known as Brix degrees. A crude way to convert Brix measurements to TDS is to multiply them by 0.85.
Optical refractometers have their limits but can often manage a wider range of sugar concentrations than a digital refractometer.
Best Refractometers for Coffee
You should familiarize yourself with a few products now that you know what to consider before buying a coffee refractometer. I recommend choosing from this list of three.
1.VST LAB Coffee III
I covered the 2022 World AeroPress Championship when it was held in Vancouver, and the vast majority of competitors there used a coffee refractometer.
The vast majority of those used the VST LAB Coffee III.
With few exceptions, these were serious competitors who knew their specialty coffee, and it was clear that the VST was their choice.
The device is about the size of your open hand, or the little credit-card device they hand you at a restaurant after your meal. It’s encased in durable rubber armor, much like those bright-orange external hard drives. It seems pretty much indestructible.
They are professional devices. They are designed to last.
The sample well is a concave, stainless steel circle on the surface of the device that resembles the business end of the Death Star. You use a syringe to place a few drops of coffee in the middle of that well, then close the cover and press Go. Within two seconds, you get a TDS reading on the display.
It reads with a precision of +/- 0.1% and is said to be accurate within 0.002%. Again, this is a professional device. If you use it correctly, you will get an accurate reading.
Using It Correctly
You need to do a few things to ensure accurate readings from the VST.
Keep the Lens Clean
Alcohol wipes are the best way to ensure that the lens through which the device reads your coffee is kept free of smudges and debris. It’s best to wipe between every reading.
Setting to Zero
Distilled water is ideal for calibrating the machine. Use a few drops of it, as you would coffee, and establish that as your “zero” reading before moving on to measuring coffee.
You may have to do this occasionally, although you can count on the VST to maintain its zero setting much longer than lesser devices.
Mind the Temperature
Room temperature is ideal for taking your readings. Again, the VST will do better than most competitors when liquids stray from room temperature, and its technology includes the ability to compensate for higher or lower temperatures. Still, the optimal temperature range for the device is between 15° and 40° C. Outside of this range, you may not get accurate readings.
You might be thinking, “Wait, I’ve just brewed hot coffee and now I have to wait for it to come down to room temperature?” But you’d be surprised how quickly this happens. Once you’ve drawn a small amount of coffee into your syringe, you can squirt it into a separate cup and it should cool down within 30 seconds. Then you’re ready to transfer it to the VST.
VST recommends that you filter espresso before attempting to take readings, and provides special filters that attach to the syringe. This step is unnecessary when measuring pour-over or AeroPress coffee that has already passed through a paper filter.
The device is powered by two AAA batteries, which should last you more than 4,000 readings before they need to be replaced.
2. Atago PAL-Coffee
One of the simplest instruments to use with coffee is the Atago PAL-Coffee. You can measure coffee samples directly into the primed and cleaned prism, then click the button to obtain the TDS reading. It also reads Brix. Readings are reliable and simple to record.
Specifications for the Atago PAL-Coffee include:
- Temperature accuracy of +/- 1° C and accuracy of +/- 0.15% for TDS
- Measuring range of 22% for TDS
- Resolution of 0.01%
- Automatic temperature adjustments
Like the VST, the Atago runs on two AAA batteries.
It falls short of the VST in a couple of areas: consistency, and need for recalibration.
You’ll have a hard time finding anyone who questions the VST’s consistency, but the Atago may have you doing the occasional double-take when a reading seems off.
Sometimes this is a calibration issue. You may have to set the zero mark again using distilled water. For whatever reason, this seems to be necessary more often with the Atago than with the VST.
3. DiFluid Coffee TDS Refractometer
Finally we have the DiFluid refractometer, which is a relatively new entry to the market and comes in at a much lower price point than the other two.
It wouldn’t be accurate to describe the DeFluid as a competitor to the two coffee refractometers described above. It isn’t in the same league. However, it could serve a purpose for the home brewer who wants a little feedback on their brew.
Remember, none of these devices actually improve the taste of your coffee. That part is up to you. So it’s understandable if you don’t want to fork out hundreds of dollars.
The DiFluid TDS refractometer (not to be confused with their Brix refractometer) is about one-tenth the size of the VST, smaller than an Apple TV remote.
You can re-charge it using a USB-C cable, and it connects to an app via Bluetooth. The app will show you whether your coffee falls within the Specialty Coffee Association-recommended TDS readings for certain brewing methods. However, you don’t have to use the app—the device also shows the readings on a display. One cool thing about the app is that it can store your results for future reference.
The drawbacks of this device are:
- It performs quite poorly when coffee is not at room temperature.
- You need to reset it to zero quite frequently.
So, you’ll need to take care to bring your sample down to room temperature first if you want to get an accurate reading.
The device also slips out of calibration quite easily, and if you want to be confident in the results, you should probably set it to zero before each use.
That said, many home baristas credit the DiFluid for helping them dial in their espresso.
The fact that you can take it anywhere very easily is a bonus.
As for specs, the key numbers are:
- Range of 0%–26%
- Precision of +/- 0.03%
- Rechargeable lithium polymer battery, about 30 days use per charge
If you’re still on the fence about this one, I highly recommend watching this YouTube review from Lifestyle Labs, in which they do a great job of putting the DiFluid TDS refractometer through its paces:
What Is a Coffee Refractometer?
A refractometer is a tool that calculates the amount of light that is refracted as it passes through a liquid. In other words, it calculates the amount of light bending at the point where the atmosphere and liquid meet. This refraction measurement can give more detailed information about the liquid under consideration.
A coffee refractometer measures light refraction through coffee to calculate the percentage of total dissolved solids (TDS) and/or the sugar content (Brix). With some simple math, you can then calculate the extraction yield—essentially, how much of the coffee within your coffee beans that you managed to pull into your cup.
Why Use a Coffee Refractometer?
You can use the refractometer for coffee to determine the TDS and optimal extraction yield of a superb cup of coffee. This way, you’ll have an easier time achieving it again during future brews.
However, if your coffee tastes odd, charting TDS and extraction yield might help you determine what adjustments you need to make. It might be difficult to tell from taste alone whether your coffee is excessively strong or weak, under-extracted or over-extracted.
How Coffee Strength Is Measured
The roasted and ground coffee components that dissolve in your brewing water make up the total dissolved solids (TDS) in your morning beverage. They are essentially the coffee itself.
TDS significantly influences coffee strength. Therefore, you can work your way toward brewing better coffee by adjusting your recipe to get a different TDS value and extraction yield.
TDS is typically measured as a percentage.
Most coffee refractometers give you the TDS percentage value immediately. To calculate your coffee extraction yield from that, use the following formula:
Brewed Coffee (g) x TDS (%) / Dose (g) = Extraction Yield %
Ideal TDS for Each Brewing Method
- French Press: 1.4%–1.7% TDS
- Espresso: 8%–12% TDS
- Pour-Over: 1.2%–1.5% TDS
- AeroPress: 1.4%–1.7% TDS
How To Use a Coffee Refractometer
Step 1: Calibrate
Calibrate the refractometer with distilled water to start, then set it to zero. Remember that with a quality refractometer you won’t have to do this before each reading, but you will likely have to do it more frequently as you move down in price point.
Step 2: Prepare Coffee
After resetting the refractometer, thoroughly stir your coffee before taking a reading (coffee stratifies very quickly).
Step 3: Add Coffee
Take a tiny coffee sample using a pipette. The coffee sample should be pipetted onto the refractometer glass until it completely covers the surface.
Step 4: Take Reading
Wait for a few seconds, typically 15 to 20. Depending on your model, close the refractometer’s lid and press “Go” or “Run.” Then wait until the gadget displays the same TDS reading three times.
Step 5: Clean Up
The glass can be dried using a tissue. Then use some alcohol to clean the refractometer’s glass.
View this post on Instagram(Video) The Bizarre And Surprising Coffee Of The Nespresso Vertuo
Using TDS To Improve Your Coffee
You can alter the coffee brewing procedure to raise the TDS value, increase the extraction yield figures, and obtain coffee of greater flavor and quality. Here are some pointers for improving coffee and raising TDS values on your refractometer:
Adjust Coffee-to-Water Ratio
This is the simplest way to make your coffee stronger and, as a result, raise your TDS number. If you use more coffee in comparison to the amount of water you previously used, your TDS result will be higher. The opposite will happen if you use a higher proportion of water.
Adjust Grind Size
The more surface area your coffee has after being ground, the more water comes into contact with the bean and the more extraction occurs.
Imagine cutting a coffee bean in half. Instead of the just outer surface area, you now have the entire outer surface area plus two extra surfaces on each side of where the bean was cleaved. It’s the same bean, but with more surface area.
Now imagine what happens as you keep grinding finer. More and more surface area.
Grinding finer is a sure way to increase extraction and hence, TDS.
Adjust Brewing Temperature
Increased thermal energy during the coffee brewing process increases extraction speed and effectiveness. The result is coffee with more strength and higher TDS.
Coffee grounds will move about in the water, and the coffee bed will become tumultuous if you stir while your coffee is brewing. The number of coffee grounds exposed to the hot water will vary depending on how quickly you stir, which results in better extraction and stronger coffee. To put it another way, stronger coffee results from more turbulence.
Brewing a specialty coffee that scores above 80 points on a 100-point scale can be challenging and requires some consistency in order to fine-tune and get the most out of your brew. TDS can be a crucial tool for understanding how your coffee is being extracted.
Maybe it’s too technical for the ordinary home barista, but if you are keen to learn how the changes you make in your process affect the coffee in your cup, a coffee refractometer can give you a lot of information. If you aren’t ready for the VST or the Atago, perhaps the DiFluid is enough to start you on the path.
About the Author…
Erik worked as a journalist at the Vancouver Province newspaper for 18 years before he founded Bean Poet. He spent half that time as a sports editor and the other half overseeing the newsroom’s digital channels. He spent all of it fuelled by coffee—except for a short-lived green tea phase in 2003 that he’d just as soon forget about. Erik once ordered an espresso in Italy and watched the barista toss his first three attempts down the sink before finally pulling one worth serving. The coffee was divine.
Thumbnail image: © AWasteOfCoffee
Do I need a refractometer for coffee? ›
You don't necessarily need a coffee specific refractometer, but they will be more accurate. More importantly, coffee refractometers come with the necessary software to make coffee-related calculations like TDS and extraction yield.What information does refractometer provide in coffee? ›
Refractometers provide a measurement of the percentage of total dissolved solids and, when paired with data regarding the coffee dose and brewing-water weight, extraction yields of the brew.Can a refractometer measure TDS? ›
The most common way to measure TDS is with a refractometer.Can you use a Brix refractometer for coffee? ›
The Brix scale is now the agreed standard for the coffee industry, and readings are calculated using a refractometer.How do I choose a refractometer? ›
- Select a refractometer that measures what you need. Refractometers measure numerous parameters. ...
- Model Selection. ...
- Measurement Range. ...
- Accuracy. ...
- Automatic Temperature Compensation. ...
- Additional Functions & Features. ...
The disadvantage of this refractometers is that the scale was prepared for liquid on the exact composition and if the measured liquid has a different composition the read value may not be accurate.How many types of refractometer are there? ›
There are four main types of refractometers, traditional handheld refractometers, digital handheld refractometers, laboratory or Abbe refractometer and incline process refractometers.How accurate is a refractometer? ›
With careful use, a 0–30 Brix refractometer is precise to within 0.2–0.3 Brix. As such, it is less precise than a good hydrometer. However, it can provide a quick measurement of gravity to within about one “gravity point” at times when cooling the wort for a hydrometer sample would take too much time.What is the ideal TDS for coffee? ›
According to the Specialty Coffee Association of America (SCAA) the ideal TDS range for the water used to brew coffee is 75-250 ppm. The target TDS is 150 ppm (3). The target TDS of 150 ppm should lead to a properly extracted cup of coffee with balanced flavors and acidity.Can a refractometer be wrong? ›
You MUST calibrate a refractometer even if it's brand new. If you've never calibrated your refractometer or you did it incorrectly, you may as well use a swing-arm plastic hydrometer which would be more accurate. Look through the eye piece of your refractometer.
Are all refractometers the same? ›
Different types of refractometers are available depending on the application. Refractometers can be handheld, compact, benchtop, Abbe, and Brix as well as different types for measuring materials such as salt, sugar or battery acid.What happens if Brix is too high? ›
High brix levels can pose problems during primary fermentation and secondary fermentation. Stuck primary fermentations are common because many yeast strains are inhibited at high alcohol levels. These conditions can cause wines with residual sugars of between 1-4%.Does higher Brix mean more sugar? ›
The Brix value tells you how much dissolved sugar is in a liquid solution. This value is indicated in degrees Brix. One degree of brix means that a hundred grams of liquid solution contains one gram of sugar. So: the higher the Brix value, the sweeter the liquid solution.Can you use olive oil to calibrate a refractometer? ›
If you do not have a reference solution supplied with your instrument, it is possible to use oils that you have in your kitchen to calibrate your refractometer. For instance, extra virgin olive oil can be used, as can liquid paraffin. Extra virgin olive oil measures 71-72 Brix.Do you need to calibrate a refractometer? ›
New refractometers should always be calibrated prior to being used. Calibration is similar to reading a sample. To calibrate the refractometer, do the following: Make sure the calibration fluid* and the refractometer are at the same temperature.Does temperature affect refractometer readings? ›
Temperature is one of the single most important factors influencing accurate refractometer readings and is one of the largest sources of error in measurement. Refractive index is VERY dependent on temperature.Does a refractometer measure pH? ›
The pH meter is used to tell the pH level or acidity of the grapes. The refractometer measures the Brix which is the amount of sugar in the grapes.What are the most common uses for the refractometer? ›
Refractometers are used in a variety of applications: From the determination of the purity and concentration of ingredients of medications to the measurement of the sugar content of food and beverages and the analysis of petroleum oil. The dilution of sunflower oil with cheap oils can also be detected with this device.What type of water is used in calibrating the refractometer? ›
Water is the most commonly used sample to calibrate zero.
Refractometer Calibration standards are:
Shelf life of unopened bottle is 5 years. Shelf life of opened bottle is 2.5 years. Fluids calibrate at temperatures between 20°C and 40°C are accurate to 0.0001 Refractive index. Fluids calibrate at temperatures above 40°C are accurate to 0.0005 Refractive index.
What does Brix mean in refractometer? ›
Degrees Brix (symbol °Bx) is the sugar content of an aqueous solution. One degree Brix is 1 gram of sucrose in 100 grams of solution and represents the strength of the solution as percentage by mass.What do the numbers on a refractometer mean? ›
Refractometers measure the degree to which the light changes direction, called the angle of refraction. A refractometer takes the refraction angles and correlates them to refractive index (nD) values that have been established. Using these values, you can determine the concentrations of solutions.Why is refractometer better than a hydrometer? ›
First of all, a small sample size means the sample will cool much faster than a hydrometer sample would. In addition, many refractometers have temperature correction features which will allow for small differences in temperature without inaccuracies.What is better hydrometer or refractometer? ›
The biggest difference between hydrometers and refractometers is that hydrometers measure gravity while refractometers measure Brix or degrees Brix (°Bx). While both tools can be used to measure sugar content, hydrometers are more accurate when measuring gravity because they have their own built-in calibration scale.What are the advantages and disadvantages of refractometer? ›
Refractometer: Pluses and minuses
Refractometry brings several benefits as an analytic modality: Instruments are simple and relatively inexpensive, measurement is rapid, and quantitation is highly accurate. On the negative side, refractometry brings value only when the constituents of a solution are well-known.
Ultimately, the refractometer is simply another tool for your homebrewing arsenal. It won't replace the trusty hydrometer, but in the hands of an educated brewer, it can be a valuable investment.How often should a refractometer be calibrated? ›
After the refractometer has been calibrated before the first use, the interval depends primarily on the use. Frequently used instruments should be recalibrated approximately every 1 to 4 weeks. Less used models can have up to 12 weeks in between.What temperature should a refractometer be? ›
A range between 68-86ºF (20-30ºC) is the most common for temperature compensated (TC) or automatic temperature compensation (ATC) refractometers. Refractometers with larger ATC ranges are available, but are more expensive.What water hardness is best for coffee? ›
What is the best water for coffee? We conclude that hardness and high pH are your friend in terms of maximizing the extracted flavours in your coffee. But, limit your water hardness to within 50 and 80ppm and a pH between 7 and 8.5 to help get consistent extractions and prevent damage to your machines.What is an unsafe TDS level? ›
Ans: Generally, the TDS level between 50-150 is considered as the most suitable and acceptable. Ans: If the TDS level is about 1000 PPM, it is unsafe and unfit for human consumption.
What is the best water for coffee? ›
Your water should be clean and free of odours or any colourings. At a neutral PH, ideally the best water for coffee making has around 150 mg/L of total dissolved solids (TDS). You're also looking for near 10 mg/L of sodium, 40 mg/L total alkalinity and 0mg/L of chlorine.Does water temperature affect refractometer? ›
The accuracy of a refractometer is greatly impacted by temperature. The apparent density of a liquid decreases with increasing temperature. It is important therefore that the temperature of the sample, temperature of the instrument and the air temperature can all be in equilibrium before a measurement is taken.Can I calibrate refractometer with tap water? ›
"Tips on Calibrating a Refractometer
First calibrate the refractometer in pure freshwater. This can be distilled water, RO (reverse osmosis) water, RO/DI water, bottled water and even tap water with reasonably low TDS (total dissolved solids).
Lift the daylight plate and place 2 to 3 drops of the calibration liquid on the prism assembly. Close the daylight plate and allow the calibration liquid to spread across the prism without any dry spots. Wait 30 seconds so the sample can reach the temperature of the refractometer.What is the difference between TDS and Brix? ›
This validated for us that Brix is the ideal means of measurement to maintain a precise product spec at the industrial level. TDS, on the other hand, is best used as a tool for determining hot coffee extraction calibrations in commercial settings .What are the advantages of Abbe refractometer over other refractometer? ›
The Abbé refractometer has some advantages such as independence of the intensity of the light, a wide dynamic range and a small cell volume (less than 3.5 μl). A linear diode array image sensor was used to determine the critical angle of refraction.What fluids can be checked with a refractometer? ›
What is a Refractometer? Refractometers are handheld, lightweight, portable instruments used to determine the concentration of water soluble fluids such as machine tool coolants, heat treating fluids, hydraulic fluids, plating baths, detergents, antifreeze, battery acid, etc.How sweet is 20 brix? ›
In the juices of fruits and vegetables, soluble solids are mostly sugars, and the Brix measurement approximates the sugar content of a sample; 20 Brix means approximately 20% sugar, for example.How much sugar does it take to raise 1 Brix? ›
125 pounds of sugar will raise 1 gallon 1 brix or degree. One ounce is . 0625 pounds.Does temperature affect Brix reading? ›
The Brix measurement of a liquid fluctuates according to temperature. The Brix of a cold sample will measure higher than the same sample at room-temperature. When measured hot, the Brix reading will be lower.
Is 14 Brix Sweet? ›
The brix of sweet fruit.
If a wine has between . 1% and 1.7% residual sugar, it is considered “dry”. Our Viognier, Petit Manseng, Rosé, and Cabernet Franc fall into this category. If a wine has between 1.8% and 3.5% residual sugar, it is considered “off-dry”.What does 20 brix mean? ›
Dave Wilson Nursery describes it perfectly as “In the juices of fruits and vegetables, soluble solids are mostly sugars, and the Brix measurement approximates the sugar content of a sample; 20 Brix means approximately 20% sugar…”.What can I use instead of a refractometer? ›
Hydrometers can have various scales on them, but one of the most popular ones out there show specific gravity brix and even potential alcohol percentage. This is probably the more common tool over refractometers.Do I really need a coffee scale? ›
“Using a scale helps you find out where you're making mistakes. It really eliminates the mystery of weight and ratio, so you can focus more on pertinent variables, like grind size and coffee origin,” says Kelly. A digital scale helps you to achieve this certainty—not just once, but every time you brew.When would you use a refractometer? ›
Refractometers are most often used in brewing to obtain quick measures of the specific gravity of unfermented wort. With a little more effort, however, you can obtain information about fermented worts — including finding the alcohol level in your beer and the original gravity from a finished beer!Why do we need a refractometer? ›
The refractometer is a well-established instrument used for measuring the water content of liquids. It measures the refractive index of the liquid, which changes according to the moisture content.Are expensive scales more accurate? ›
3) All digital scales are reasonably accurate, no matter what the brand. There's no need to purchase the most expensive scale on the market if you only want to keep track of your weight. The authors of BMC Public Health Study didn't note any significant variance in accuracy based on the brand of digital scales.What is the best thing to use to descale a coffee machine? ›
The two most popular descaling solutions for ridding your coffee pot of limescale are white vinegar and commercial descaler.Where is the most accurate place to put a scale? ›
Put your scale on a hard, flat, level surface, avoiding carpeting or uneven flooring. The simplest way to calibrate it, after putting it in place, is to adjust the weight to exactly 0.0 pounds with nothing on it.
What is the golden ratio for coffee? ›
A general guideline is called the "Golden Ratio" - one to two tablespoons of ground coffee for every six ounces of water. This can be adjusted to suit individual taste preferences.How many beans to grind for 1 cup of coffee? ›
0.38 ounces or 10.6 grams of ground coffee beans must be used to make a 6-ounce cup of coffee. This equates to around 2 teaspoons of coffee grinds. Use a digital kitchen scale to precisely measure these weights. Put on the scale a small glass or plastic bowl or cup.How much coffee should I use for a 16 oz cup? ›
2 servings of regular coffee: 16oz of water | 0.88oz or 26.2g of coffee. 2 servings of strong coffee: 16oz of water | 1.1oz or 31.5g of coffee.How often should you calibrate a refractometer? ›
After the refractometer has been calibrated before the first use, the interval depends primarily on the use. Frequently used instruments should be recalibrated approximately every 1 to 4 weeks. Less used models can have up to 12 weeks in between.