# What this espresso calculator actually measures
Espresso recipes are easier to repeat when they are written as masses and times. A brew ratio is beverage mass divided by dry dose. A 18 g dose that yields 36 g in the cup is a 1:2 shot. Contact time is the timer reading minus any preinfusion soak. Flow rate is beverage mass divided by that contact time.Weigh the cup, do not trust milliliters
Crema and temperature make volume readings noisy. Specialty recipes almost always use grams in and grams out. If you only have a volume mark, treat 1 ml as a rough 1 g stand-in and switch to a scale as soon as you can. 1:2 Common starting ratio
20 to 32 s Typical contact window
18 to 22% Often cited yield band
# Shot styles from brew ratio
The labels ristretto, normale, and lungo are ratio families, not flavor scores. This tool uses mass ratio cutoffs near 1:1.5 and 1:2.5 as a map, because those bands match how many specialty bars write recipes. Traditional volume based Italian definitions are different and are not applied here.| Style | Mass ratio | Example on 18 g | What the glass shows |
|---|---|---|---|
| Ristretto | Below 1:1.5 | About 20 g out | Fill sits near the 1:1 mark |
| Normale | 1:1.5 to 1:2.5 | 36 g out at 1:2 | Fill meets the gold 1:2 line when time is typical |
| Lungo | Above 1:2.5 | About 54 g out | Fill climbs toward the 1:3 mark |
| Turbo | Often near 1:2.2 | 40 g out in about 15 s | Fast pace, still a measured recipe |
# Extraction yield needs a TDS reading
Total dissolved solids (TDS) is the strength of the beverage, usually read with a refractometer. Extraction yield is the share of the dry coffee that dissolved. The relationship used here is the same brewing-chart identity discussed by the Specialty Coffee Association: yield percent equals TDS percent times beverage mass divided by dose.- Measurable without TDS: dose, beverage mass, brew ratio, shot time, preinfusion, contact time, and flow rate.
- Measurable only with TDS: extraction yield. A 9.5 percent TDS on 36 g from 18 g is a 19 percent yield.
- Not a taste diagnosis: sour, bitter, or hollow flavors need grind, temperature, and puck prep. Use the flavor diagnosis tool for that work.
- Not a manufacturer spec: basket size, roast, and machine change the shot that tastes best. Treat 18 to 22 percent as a cited planning band, not a pass/fail grade.
How to use the shot lab
Pick a profile or set dose, yield, and time from the scale and timer.
Watch the glass fill to the 1:1, 1:2 and 1:3 marks as ratio and pace change.
Enable TDS only after a refractometer reading if you want extraction yield.