Coffee Brew Ratio Calculator
Coffee and water for any ratio — where a 1:16 brew is one part in seventeen, and misreading it doses you exactly one over the ratio too much.
A ratio sets strength, not extraction — the same 1:16 tastes sour or bitter depending on grind, temperature and time. And the cup will hold less than the water you poured, because wet grounds keep roughly twice their own weight. Nothing is uploaded.
A 1:16 brew is one part in seventeen
The ratio names parts of water per part of coffee, so the coffee is 5.882% of what ends up in the cup — not the 6.25% a sixteenth would be. Read it as "coffee is a sixteenth of the total" and you dose 6.25% too much, every time. It is the same fencepost that makes a 1:10 dilution take nine parts of diluent rather than ten: the colon never means "of the total".
| Ratio | Coffee is | Misread as | Overdose | For 500 g water |
|---|---|---|---|---|
| 1:12 | 7.692% | 8.333% | 8.333% | 41.67 g |
| 1:14 | 6.667% | 7.143% | 7.143% | 35.71 g |
| 1:15 | 6.250% | 6.667% | 6.667% | 33.33 g |
| 1:16 | 5.882% | 6.250% | 6.250% | 31.25 g |
| 1:17 | 5.556% | 5.882% | 5.882% | 29.41 g |
| 1:18 | 5.263% | 5.556% | 5.556% | 27.78 g |
| 1:20 | 4.762% | 5.000% | 5.000% | 25.00 g |
The size of the mistake is worth having exactly: it is one over the ratio, with no rounding anywhere in it. 6.25% at 1:16, and exactly 5% by 1:20.
Which is why it ruins espresso and hides in cold brew
Because the overdose is one over the ratio, it is worst where the ratio is smallest. At espresso-ish ratios it is 50% — half again as much coffee as you meant. At cold-brew ratios it is 5%, which will vanish into the noise. That is exactly tenfold between them, since the ratio of the errors is the inverse ratio of the parts.
| Method | Roughly | Cost of misreading it |
|---|---|---|
| Espresso, roughly | 1:2 | 50.00% |
| Moka pot | 1:10 | 10.00% |
| Strong filter | 1:15 | 6.67% |
| Standard filter | 1:17 | 5.88% |
| Cold brew, drunk neat | 1:20 | 5.00% |
In practice, weigh the water and multiply. 500 g of water at 1:16 takes 31.25 g of coffee, and the recipe scales straight — double the water, double the coffee.
| Water | Coffee at 1:16 | In the pot |
|---|---|---|
| 250 g | 15.63 g | 265.6 g |
| 350 g | 21.88 g | 371.9 g |
| 500 g | 31.25 g | 531.3 g |
| 1000 g | 62.50 g | 1062.5 g |
How to use
- Enter the water you plan to brew with.
- Enter the ratio, as the number after the 1.
- Or enter the coffee you have and work backwards.
- Read the dose, and what misreading the ratio would cost.
Frequently asked questions
What does a 1:16 ratio actually mean?
One part coffee to sixteen parts water — so the coffee is one part in SEVENTEEN, or 5.882% of what ends up in the cup. It is not a sixteenth of the total, which would be 6.25%.
How much does that misreading cost?
Exactly one over the ratio. At 1:16 you dose 6.25% too much, at 1:15 it is 6.67%, and at 1:20 it is exactly 5%. There is no rounding anywhere in it.
Where does that matter most?
At the strongest ratios, because the error is one over the ratio. Espresso-ish ratios around 1:2 are 50% out — half again as much coffee as you meant — while cold brew at 1:20 is 5% and vanishes into the noise.
How much coffee for 500 g of water?
31.25 g at 1:16. Weigh the water and divide by the ratio; the recipe then scales straight, so double the water means double the coffee with nothing else to think about.
Should I weigh the water or the total?
The water, by convention. Weighing to a 500 g TOTAL at 1:16 uses 29.41 g rather than 31.25 — a different drink, and the source of a good deal of confusion between recipes.
Is this the same as a dilution ratio?
The same fencepost, yes. A 1:10 dilution takes nine parts of diluent rather than ten, for exactly the reason a 1:16 brew is one part in seventeen: the colon names parts against one part, never a share of the total.
Will this make my coffee taste right?
It sets strength, not extraction. The same 1:16 can taste sour or bitter depending on grind, water temperature and contact time — the ratio decides how much coffee is in the cup, not how well it was pulled out of the grounds.
Does this send anything anywhere?
No. Every figure is computed in your browser, and nothing is uploaded or stored.
🔒 This tool runs entirely in your browser. Nothing you enter is uploaded, logged, or stored.