2
x
1.29
g/s
0
/100
100
/100
100
/100
90
/100
1,800
%
2
x
1.29
g/s
0
/100
100
/100
100
/100
90
/100
1,800
%
Espresso extraction is the process of forcing hot water (approximately 93°C) under high pressure (typically 9 bars) through a compacted puck of finely ground coffee. The result is a concentrated, emulsified beverage defined by its rich crema, intense aroma, and layered flavor complexity. Mastering espresso extraction requires understanding the relationship between three key variables: dose, yield, and brew time.
The Espresso Extraction Calculator analyzes your espresso shot by computing the brew ratio — the ratio of coffee input (dose) to espresso output (yield) — and assessing it against specialty coffee benchmarks to determine the shot type and provide an extraction quality score.
The brew ratio is expressed as 1:X, where 1 represents one part coffee and X represents the multiple of espresso produced. The four standard shot classifications based on brew ratio are:
Ristretto (1:1 to 1:1.3): An extremely short, concentrated shot with a very high dose-to-yield ratio. Ristrettos are sweeter and more syrupy but have less total dissolved solids extracted. They emphasize the early flavor compounds extracted — sweetness and body — while cutting off before bitterness develops.
Short / Short Ristretto (1:1.3 to 1:1.5): A slightly longer version of the ristretto, common in Italian coffee culture. Still short but less extreme.
Standard Espresso (1:1.5 to 1:2.5): The most common range for modern specialty espresso. A 1:2 ratio (e.g., 18g in, 36g out) is the most widely taught starting point, offering a balanced cup with good sweetness, acidity, and bitterness. The SCA's World Barista Championship typically targets 1:2 to 1:2.5.
Lungo (1:2.5 to 1:3.5+): A longer shot with more water passing through the puck. Lungos extract more bitter compounds and produce a higher-volume, lower-concentration cup. They are popular in Northern Europe but controversial among specialty coffee purists.
Brew time (25–30 seconds for a standard double espresso) and flow rate (approximately 1–2 ml/s) are critical secondary indicators. The extraction score integrates both brew ratio and time deviation from the ideal 27.5-second target to give a 0–100 quality assessment.
The brew ratio is calculated as: Brew Ratio = Yield (g) ÷ Dose (g). Shot classification is determined by comparing the ratio to industry-standard thresholds: below 1.3 = ristretto, 1.3–1.5 = short, 1.5–2.5 = standard espresso, above 2.5 = lungo. The extraction score penalizes deviations from a target ratio of 2.0 and a target brew time of 27.5 seconds: Score = 100 − |ratio − 2.0| × 20 − |time − 27.5| × 2, clamped between 0 and 100. Flow rate is calculated as: Flow Rate (ml/s) = Yield (g) ÷ Brew Time (s).
A score of 80–100 indicates an excellent extraction with ratio and time both close to ideal. 60–79 suggests minor adjustments needed — check if the shot is running too fast or too slow. Below 60 indicates significant deviation — adjust grind size, dose, or yield. A shot type of 1 (ristretto) or 4 (lungo) is intentional for some recipes but usually indicates an imbalance if unintended. Flow rate of 1–2 ml/s is normal for a well-extracted espresso.
Inputs
Results
18g in, 36g out = 1:2 ratio. Perfect standard espresso. 28 seconds brew time is in the ideal range. Extraction score 97/100. Flow rate 1.3ml/s — excellent.
Inputs
Results
18g in, 20g out = 1:1.1 ratio (ristretto). Score of 30 reflects significant deviation from standard. Intentional for espresso-milk drinks where sweetness and concentration are prioritized.
The most widely recommended starting point is 1:2 (e.g., 18g in, 36g out) for a standard double espresso. This ratio produces a balanced cup with sweetness, acidity, and bitterness in harmony. Specialty coffee competitions typically target 1:2 to 1:2.5.
A ristretto uses a very low yield relative to dose (1:1 to 1:1.3), producing a sweet, concentrated, syrupy shot. A lungo uses a high yield (1:2.5 to 1:3.5+), resulting in a more bitter, higher-volume shot with lower concentration.
Weighing the yield in grams ensures the brew ratio is precisely controlled. Volume measurements (in ml) are unreliable because espresso crema is aerated and the density varies. Scales give accurate, reproducible results every time.
A shot running too fast (under 20–22 seconds) usually means the grind is too coarse, the dose is too low, or the coffee is tamped too loosely. Water finds the path of least resistance and under-extracts the coffee.
A shot running too slow (over 35 seconds) usually means the grind is too fine, the dose is too high, or the tamp was too hard. Channeling — where water finds a narrow path through the puck — can also cause inconsistent flow.
Channeling occurs when water finds a weak spot in the coffee puck and flows through that one channel rather than evenly through all the grounds. It causes uneven extraction — part of the puck is over-extracted, part is under-extracted. Distribution tools and WDT help prevent channeling.
Yes. Light roasts are often brewed at a slightly higher ratio (1:2.5 to 1:3) to coax out their delicate fruity and acidic notes. Dark roasts are commonly brewed at 1:1.5 to 1:2 to avoid exaggerating bitterness. Adjust based on taste.
The classic standard is 9 bars at the group head, though many modern machines allow pressure profiling. Some specialty baristas prefer lower pressure (6–8 bars) for certain light roasts. Home machines should be checked with a pressure gauge if possible.
Higher temperatures (94–96°C) extract more quickly and aggressively, emphasizing body and bitterness. Lower temperatures (88–92°C) are often preferred for light roasts to reduce harshness and highlight fruity acidity. Most machines target 90–95°C.
TDS stands for Total Dissolved Solids, expressed as a percentage. For espresso, TDS typically ranges from 8–12%. A refractometer measures TDS precisely and can be used with brew ratio to calculate extraction yield (EY), giving a quantitative measure of how much coffee was extracted.
Roboculator Team
The Roboculator Team explains calculations, planning tools, and practical formulas in clear language for real-life situations.
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