BREW LAB

graycano · brew the moment

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Missing something in your coffee corner?

Every piece of gear here sits inside the calculator as a coefficient: the grinder in the click conversion, the papers in the extraction offset, the concentrates in the water calculation, the refractometer in the measurement. Swap one of them and the result moves, and the calculator knows by how much.

Grinder
C40 Nitro Blade

The calculator’s reference grinder. Every click figure is calibrated to its 30 microns per click, and every other grinder is converted from it.

299 €
Grinder
C60 Baracuda

Same house, a bigger burr: the Baracuda grinds well over a gram per second at filter settings. The calculator carries the C40 click scale over to it, which is not a measured figure.

598 €
Grinder
X25 Trailmaster

The same NITRO BLADE burr as the C40, in a light unibody built for the trail. The calculator’s click figures therefore hold unchanged.

228 €
Dripper
Graycano Dripper

The conical brewer in the model. Its bed holds back around 2.0 g of water per gram of coffee, and that is exactly what the calculator subtracts from the beverage weight.

65 € to 75 €
Flat bed
Graycano Coin

Turns the Dripper into a flat-bottom brewer. The model then works with a more even bed, more body and around 0.02 percentage points less TDS.

16 €
Filter paper
Filter GC01

The zero point of the paper scale in the model: it shifts extraction by nothing. Every other paper is calculated against this one.

14 €
Filter paper
Filter Fast Cone

Worth 0.45 percentage points of extraction below the GC01 in the model. In return the fast flow lets you grind finer without stalling the bed.

45 €
Filter paper
Filter Fast Flat

The same maths as a flat bed for the Coin: 0.40 percentage points below the GC01, with a slightly more even bed.

45 €
Filter paper
Filter B3 Cone

Worth 0.15 percentage points above the GC01 in the model, plus more body and a longer finish. Developed with Brewers Cup world champion Matt Winton.

45 €
Water
APAX LAB Box Set

The three concentrates behind the water calculation. What you dial in above in grams per litre is the dose out of exactly these bottles.

90 €
Water
KONFLUX

Works with quartz instead of magnesium and pushes body, sweetness and texture above all. SCA Best New Product 2026.

32 €
Measurement
DiFluid R2 Extract

The instrument for the field above. Once a measured TDS sits in it, it replaces the prediction across the whole read-out.

225 €

Documentation

How the Brew Lab calculates

The equation

Extraction yield tells you what share of the coffee grounds has dissolved into the water. It follows from three numbers: the concentration of the finished beverage, its mass, and the dose of coffee you started with. That concentration is called TDS, total dissolved solids, and it is read off a refractometer.

Extraction % = TDS % × beverage mass g / dose g 1.32 % TDS in 250 g of beverage from 18 g of coffee gives 18.3 % extraction.

The Brew Lab runs this equation in both directions. Without a refractometer it estimates TDS from your recipe and what you know about the bean. The moment you enter a measured value it reverses the calculation and replaces the estimate throughout the whole result.

Two axes, not one

Extraction and strength get lumped together in everyday talk, yet they hang off different levers. Extraction describes how much came out of the coffee, and it decides between sour and bitter. Strength describes how much of that sits in a single sip, and it decides between thin and heavy.

For filter coffee the grind moves extraction above all, the ratio moves strength. For espresso the shot time takes the role of the grind and the yield takes the role of the ratio. Change both axes in the same brew and you will not know afterwards which lever did the work. That is why the correction panel only ever names one change.

SCA Brewing Control Chart

The chart plots extraction along the horizontal axis and TDS along the vertical one. The solid rectangle is the Golden Cup zone of the Specialty Coffee Association: 18 to 22 % extraction at 1.15 to 1.35 % TDS. The dashed strip above it reaches 1.42 % and marks the range many modern filter recipes deliberately sit in.

The diagonals are brew ratios. Move along a diagonal and extraction shifts while the ratio of coffee to water stays put. Espresso has no official Golden Cup equivalent. The corridor of 8 to 12 % TDS is industry practice, not a standard.

Grind size in clicks

Grinders do not speak the same language. The Brew Lab therefore states the recommended grind in micrometres and converts it into clicks as well: Comandante C40 with and without Red Clix, 1Zpresso JX-Pro, Timemore C2 and C3, Kingrinder K6, Baratza Encore and Fellow Ode Gen 2.

Those are comparison figures, not a calibration. Every grinder has its own travel per click, and the zero point moves as a burr set breaks in and wears. Take the number as a starting point and note down your own offset. From then on it holds for every further recommendation.

Limits of the model

The Brew Lab is a model, not a measuring instrument. Its forecast rests on published relationships between grind size, temperature, contact time and solubility, plus reference values for processing, variety and roast level. How far one particular lot departs from that is something only a measurement can tell you.

The axes acidity, sweetness, bitterness, body and aftertaste are known to respond to extraction and TDS. Clarity and astringency, by contrast, are practitioners' terms rather than official scoring attributes. Everything is calculated in the browser, with no server in between.

Frequent questions

Multiply the measured TDS in percent by the mass of the finished beverage in grams, then divide by the coffee dose in grams. 1.32 % TDS in 250 g of beverage from 18 g of coffee gives 18.3 % extraction. Without a refractometer the Brew Lab estimates TDS from grind size, ratio, temperature and contact time and derives the extraction from that.

The Specialty Coffee Association names 1.15 to 1.35 %. Many modern recipes deliberately go up to 1.42 %, because the cup reads denser without being over-extracted. What matters is the combination of both axes: high TDS at low extraction tastes sour and heavy, low TDS at high extraction tastes thin and bitter.

No. Without a reading the Brew Lab gives you a forecast from the recipe, and that is enough to dial in the right direction. A refractometer turns the forecast into a measurement: once TDS and beverage weight are entered, the whole result is calculated from your numbers instead of the model.

Sour and thin is nearly always under-extraction. Grind finer and leave everything else alone; on a Comandante C40 two or three clicks is a good first step. If it stays sour, raise the water from 93 to 95 or 96 °C. The ratio is the wrong lever here, it shifts strength rather than extraction.

That is high extraction at low TDS: ground too fine and brewed at too wide a ratio at once. Go coarser to take out the bitterness, then tighten the ratio afterwards, say from 1:17 to 1:15, to bring the body back. One after the other, not in the same brew.

The conversion describes how far the burr cone travels in micrometres per click. Manufacturing tolerances, the break-in of a new burr set and wear all shift the zero point by several clicks. The number is a starting point. Once you have checked it against your own reference recipe, the same offset applies to every later recommendation.

Yes. The switch in the page header moves the tool to espresso. It then works with brew pressure, puck preparation and pre-infusion, and the correction runs through shot time and yield instead of grind size and ratio. The extraction target stays at 18 to 22 %, and the TDS corridor of 8 to 12 % is industry practice, not an SCA standard.

For how the bean itself feeds into the calculation, read What is Specialty Coffee. If you would rather taste it in person, find us at the Graycano Brew Bar. The matching hardware is further up this page.