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Tool · extraction yield

Extraction yield calculator

Extraction yield (EY) is the share of the dry coffee that ended up dissolved in your drink. Enter a refractometer TDS reading, the dose and the weight of the brew, and the calculator shows the result, the formula it used and where it falls against published reference ranges.

Updated 2026-10-14 · sources listed at the end

EY% calculator

Weigh the brewed coffee that ends up in the cup or server.

Extraction yield20.8%
Dissolved solids4.16 g
Beverage : dose1 : 16

EY = 1.30% × 320 g ÷ 20 g = 20.8%

20.8% is inside the classic 18–22% box. TDS 1.30% is inside the classic 1.15–1.35% box and the SCA home-brewer target of 1.15–1.55%.

With this dose and weight, a TDS of 1.25% would give 20.0%.

Percolation (pour-over, drip, espresso):
EY (%) = TDS (%) × beverage weight (g) ÷ dose (g)

Full immersion, at equilibrium (Liang et al. 2021):
EY = TDS ÷ (1 − TDS) × brew water (g) ÷ dose (g) (TDS as a fraction: 1.30% = 0.013)

dissolved solids (g) = EY × dose

The first line is the percent-extraction formula used in UC Davis drip-coffee research: PE = TDS × Mbrew ÷ Mgrounds, where Mbrew is the total delivered mass of brewed coffee. Wikipedia’s Coffee extraction article gives an espresso example: 18 g of coffee brewed into 36 g of beverage at 10% TDS is a 20% extraction yield (10% × 36 ÷ 18).

The three inputs

  • Dose — the dry ground coffee, in grams. SCA Standard 310-2021 defines brew yield (percent extraction) as the percentage in mass of the coffee grounds that is extracted into the brew.
  • Beverage weight — the brewed coffee you collected, weighed. For espresso it is the shot weight, the “yield” of the espresso ratio. It is not the water you poured: wet grounds hold some back, so the cup weighs less.
  • TDS — total dissolved solids, the mass fraction of solubles in the drink, also called strength. It has to be measured. SCA Standard 310-2021 measures brew strength with a coffee refractometer, and the UC Davis temperature study used a digital refractometer with one drop of cooled coffee.

Reference ranges

There is no single target, and the sources do not all draw the box in the same place. Each range below is shown with where it comes from.

RangeTDSEYSource
Classic brewing control chart “ideal” region (Lockhart, 1957)1.15–1.35%18–22%As cited by Batali et al. 2020 and Liang 2023 (UC Davis)
North America, typical1.15–1.35%18–22%Wikipedia, Coffee extraction
Nordic countries1.30–1.50%—Wikipedia, Coffee extraction
European countries1.20–1.45%—Wikipedia, Coffee extraction
SCA home-brewer standard, at 55 g per kg of water1.15–1.55%not statedSCA Standard 310-2021
Espresso—generally 15–25%Wikipedia, Coffee extraction
Espresso, “usually targeted”—18–22%University of Oregon, on Cameron et al. 2020
Full immersion at equilibriumset by ratio≈21% (20.70 ± 1.08% measured)Liang et al. 2021

Wikipedia’s article calls yields under 18% under-extracted and over 22% over-extracted. Treat the edges loosely: the UC Davis team behind the new chart point out that most experts cannot tell a 17.9% extraction from 18.1%, although the classic chart implies they differ.

Extraction yield against TDS, with the classic ideal box Chart with extraction yield from 14 to 26 percent across and TDS from 0.9 to 1.7 percent up. A shaded box covers 18 to 22 percent extraction and 1.15 to 1.35 percent TDS. A lighter band runs across the chart from 1.15 to 1.55 percent TDS. Three diagonal lines show beverage-to-dose ratios of 14, 16 and 18. A dot marks the worked example: 20.8 percent extraction at 1.30 percent TDS. Numbered markers 1 to 4 match the list below. 0.91.11.31.51.7 14161820222426 extraction yield, % TDS, % ×14×16×18 1 2 3 4
  1. Classic “ideal” box — 18–22% extraction, 1.15–1.35% TDS (Lockhart 1957, as cited by the UC Davis papers).
  2. SCA home-brewer band — 1.15–1.55% TDS, the strength target in SCA Standard 310-2021 (dashed lines).
  3. Beverage-to-dose lines — every brew with the same beverage weight per gram of coffee sits on one line: TDS = EY ÷ (beverage ÷ dose). Shown for ×14, ×16 and ×18.
  4. Worked example — 20 g of coffee, 320 g of brew, 1.30% TDS: 20.8% extraction, on the ×16 line.
Drawn by pourxlab.com for this page from the ranges in Batali et al. 2020, Liang 2023 and SCA Standard 310-2021 (sources 1, 3 and 6) and the percolation formula above. Axes to scale. Lines are beverage-to-dose ratios, not the brew-water ratios printed on the original chart.

Why immersion gets its own formula

In a French press or a cupping bowl, part of the liquid stays in the grounds — in the UC Davis immersion experiments, 2.48 ± 0.19 g of liquid per gram of coffee — and that liquid is just as strong as the coffee you pour off. Weighing only the decanted coffee therefore undercounts what dissolved. Liang, Chan and Ristenpart (2021) used mass conservation instead: at equilibrium, E = TDS ÷ (1 − TDS) × Rbrew, where Rbrew is the mass of water per mass of coffee. As they put it, because TDS is readily measured, the equation “provides an easy means to assess the extraction yield” of a full-immersion brew.

A worked example: 30 g of coffee steeped in 500 g of water reads 1.30% TDS. The immersion formula gives 0.013 ÷ 0.987 × 500 ÷ 30 ≈ 22.0%. That brew holds about 507 g of liquid (500 g of water plus 6.6 g of dissolved coffee). If about 74 g of it stayed in the grounds (30 g × 2.48) and only the roughly 432 g poured off went into the percolation formula, the result would read about 18.7% — the same brew, about three points lower.

The same research found that immersion extraction settles near 21% across a wide range of brew ratios, and that brew temperatures from 80 °C to 99 °C (176–210 °F) did not change the final equilibrium TDS or extraction. Its practical message: in immersion, the brew ratio sets the strength, while extraction stays close to its equilibrium value — higher extraction cannot be reached with a single full-immersion brew. The same paper notes that the oven-drying method of measuring extraction gives significant underestimates for immersion coffee.

Reading a result

  1. Measure the same way every time. Same refractometer, sample cooled, one drop, beverage weighed on a scale.
  2. Place the brew on the chart. EY tells you how much of the coffee dissolved; TDS tells you how strong the cup is. A cup can be weak and well extracted, or strong and under-extracted.
  3. Compare with taste, not just the box. In the UC Davis sensory study behind the new chart, bitterness rose with both TDS and extraction; sourness rose with TDS and fell with extraction; sweetness was highest at low TDS and low extraction.
  4. Change one variable. For drip and pour-over, UC Davis’s William Ristenpart describes using the scale and the brew ratio together with grind size and brew time to steer toward the flavors you want. For immersion, change the ratio.

Common questions

Can I calculate extraction without a refractometer?

Not with this formula: TDS is a measured input, and every source above measured it with a refractometer. Without one, the brew ratio is still a useful control — see the coffee ratio chart.

Why is my espresso TDS so much higher than filter coffee?

Espresso uses far less liquid per gram of coffee, so the same fraction of dissolved coffee is packed into a much smaller drink. Wikipedia’s worked example — 10% TDS at 18 g in, 36 g out — is still a 20% extraction yield, the same as a filter cup at 1.25% TDS with 16 g of beverage per gram of coffee.

Is the 1957 box still the standard?

It is still the reference most sources cite, but UC Davis research with the SCA’s Coffee Science Foundation produced a Sensory and Consumer Brewing Control Chart, announced in January 2025, that maps flavor attributes across TDS and extraction instead of a single ideal box. The brewing control chart explainer covers both charts in detail.

Sources

  1. Batali M.E., Ristenpart W.D., Guinard J.-X. (2020) Brew temperature, at fixed brew strength and extraction, has little impact on the sensory profile of drip brew coffee. Scientific Reports 10, 16450 (PE = TDS × M_brew ÷ M_grounds; ideal region 1.15–1.35% TDS, 18–22% PE; VST refractometer)
  2. Liang J., Chan K.C., Ristenpart W.D. (2021) An equilibrium desorption model for the strength and extraction yield of full immersion brewed coffee. Scientific Reports 11, 6904 (UC Davis, eScholarship copy: E = TDS/(1 − TDS) × R_brew; 20.70 ± 1.08%; liquid retention 2.48 ± 0.19)
  3. Liang J. (2023) The Extraction Dynamics and Sensory Quality of Full Immersion Brewed Coffee, ch. 2. PhD dissertation, UC Davis (TDS and E definitions; Lockhart 1957 range 1.15–1.35% TDS, 18–22% E)
  4. Liang J., Chan K.C., Ristenpart W.D. — How Strong Is the Coffee You’re Cupping? SCA 25 Magazine, Issue 17 (equilibrium E about 21%; oven drying underestimates; 80–99 °C)
  5. Frost S., Batali M., Guinard J.-X., Ristenpart W.D. — Towards a New Brewing Chart. SCA 25 Magazine, Issue 13 (sensory trends across TDS and PE; 17.9% vs 18.1%)
  6. SCA Standard 310-2021, Home Coffee Brewers (brew yield definition; 1.15–1.55% strength at 55 g/kg; refractometer)
  7. UC Davis Coffee Center — UC Davis Coffee Center contributes research to new brewing control chart (January 2025)
  8. Wikipedia — Coffee extraction (18–22% desirable; North American, Nordic and European strength; espresso 15–25%; 18 g / 36 g / 10% example)
  9. University of Oregon — UO chemist helps find path to consistently good espresso (January 2020; 18–22% espresso extraction)