Coffee Brew Calculator On-device
Ratio, absorbed water and a live pour timer.
Your settings and saved recipes stay on this device. Nothing is uploaded, and there is no account.
Enter your dose — we work out the brew water and what actually reaches the cup.
1:12 to 1:20
Grounds keep water. The water you pour is not the water that reaches the cup — a 1:16 brew with 288 g of water pours barely 250 g, and most calculators never subtract it.
Brew timer
Targets are cumulative — that is what your scale reads.
This browser will not keep the screen awake — it may dim mid-brew.
Advanced
2 g per gram of coffee
About 2 g per gram of coffee is a reliable starting point. Coarser grinds and deeper beds keep a little more — adjust it if your scale disagrees.
88% of the brew water reaches the cup; the rest stays in the grounds.
Added straight to the cup rather than through the coffee bed — it raises the yield without changing the extraction.
| Method | Ratio | Grind | Water | Total time |
|---|---|---|---|---|
| V60 | 1:16 | Medium-fine | 92–96 °C | 2:45–3:15 |
| Chemex | 1:16.5 | Medium-coarse | 92–96 °C | 3:30–4:30 |
| AeroPress | 1:14 | Fine-medium | 80–90 °C | 1:30–2:30 |
| French press | 1:15 | Coarse | 92–96 °C | 4:00–5:00 |
| Moka pot | 1:10 | Fine | Stovetop heat | 3:00–4:00 |
| Cold brew | 1:8 | Very coarse | 20 °C or fridge-cold | 14–18 h |
| Espresso | 1:2.2 | Very fine | 92–95 °C | 25–32 s |
Starting points to adjust to taste, not rules. Every figure is a range because beans, grinders and water all move the target.
Every figure here is a starting point to adjust to taste, not a rule. Beans, grinder, water and kit all move the target.
Nothing saved yet — set up a brew and save it.
Recipes stay on this device only — method, ratio, dose and absorption travel together.
Work out your coffee dose, the brew water and the yield that actually reaches the cup. Grounds keep roughly 2 g of water per gram of coffee, and this calculator subtracts it instead of pretending it away. Seven brewing methods, a staged pour plan with cumulative scale targets, and a live timer that keeps the screen awake while you brew. Runs entirely on your device.
About this tool
What you provide
- A brewing method: V60, Chemex, AeroPress, French press, moka pot, cold brew or espresso
- Either your coffee dose or the cup size you want, plus the ratio
- Optionally the water kept per gram of grounds, and any bypass water
What you get
- The brew water, the water kept by the grounds, and the yield that reaches the cup
- A staged brew plan with cumulative scale targets and times
- A live brew timer that keeps the screen awake where the browser supports it
Limits
- Grind, temperature and time are starting-point ranges to adjust to taste, not rules.
- Espresso has no absorption step — its ratio is dose to liquid in the cup.
- The default of about 2 g of water kept per gram of coffee is a starting point; change it if your scale disagrees.
How to use it
Pick a brewing method
Tap V60, Chemex, AeroPress, French press, Moka pot, Cold brew or Espresso — the ratio, grind, water temperature and time guidance move with it, and your dose is left alone.
Choose what to solve for
Pick I have beans to go from a dose to the cup, or I want a cup size to work back from the yield you want to the dose.
Enter the amount and ratio
Type the grams in the field (or use the − and + buttons and the 1, 2 and 4 cup chips), then set the ratio with the slider or the Strong, Balanced and Light presets.
Read the yield in the cup
The tiles show the dose, the total brew water and the yield that actually reaches the cup once the grounds keep their share, with the subtraction spelled out beneath.
Start brewing and follow the timer
Tap Start brewing and follow the stages — pour-over methods give cumulative scale targets to pour to, while immersion and cold brew give add, steep and press steps; the screen is kept awake while the timer runs and released when you pause or reset.
Frequently asked questions
Why is the amount in the cup less than the water I pour?
Wet grounds hold on to water. At roughly 2 grams retained per gram of coffee, an 18 g dose keeps about 36 g, so 288 g of brew water leaves around 252 g in the cup. The calculator subtracts that retention instead of pretending the two numbers are the same.
Why does espresso not show a retention figure?
For espresso the ratio is read as dose to liquid in the cup, so the yield is already the shot weight and there is no separate absorption step to subtract.
Are the grind, temperature and time values fixed rules?
No. They are generic starting parameters meant to be adjusted to your beans, grinder and taste. Every figure is shown as a range you are expected to move.
Does the timer keep the screen awake?
While a brew is running the page requests a screen wake lock where the browser supports it, and releases it as soon as you pause or reset.