Coffee Ratio Calculator
Work out grams of coffee for any amount of water using the golden 1:15–1:18 ratio.
320 g water ÷ 16 = 20 g coffee (≈ 1.3 cups at 240 mL each).
Taste is personal — treat the ratio as a starting point. Grind size, brew method, water temperature, and bean freshness all shift the result, so adjust up or down by a gram or two until it tastes right to you.
The coffee-to-water ratio is grams of coffee per grams of water, and the widely cited golden ratio is about 1:15 to 1:18 — roughly 55–60 g of coffee per litre. To find the dose, divide water by the ratio: 320 g of water at 1:16 needs 320 ÷ 16 = 20 g of coffee.
How the coffee ratio works
A brew ratio compares the weight of ground coffee to the weight of water, written as 1:n — 1 gram of coffee for every n grams of water. Because 1 millilitre of water weighs about 1 gram, you can measure water by volume and treat the numbers as interchangeable. A smaller number (1:15) means more coffee per cup and a stronger brew; a larger number (1:18) means less coffee and a milder cup.
and in reverse: water (g) = coffee (g) × ratio
Worked example
Brewing a 350 mL mug at a balanced 1:16.
- 1 Weigh or measure the water. A 350 mL mug of water weighs about 350 g.
- 2 Choose a strength ratio. Pick 1:15 for strong up to 1:18 for mild; 1:16 is a balanced starting point.
- 3 Divide water by the ratio. 350 ÷ 16 ≈ 21.9, so use about 22 g of ground coffee.
- 4 Taste and adjust. Too weak? Drop to 1:15 or add a gram. Too strong? Move toward 1:18.
Ratios and strength
Grams of coffee per litre (1000 g) of water, and for a 240 mL cup.
| Ratio | Strength | Per litre | Per 240 mL cup |
|---|---|---|---|
| 1:15 | Strong | ≈ 67 g | 16 g |
| 1:16 | Balanced | ≈ 63 g | 15 g |
| 1:17 | Mild | ≈ 59 g | 14 g |
| 1:18 | Mildest | ≈ 56 g | 13 g |
Where the ratio is only a starting point
Grind and method matter. The same 1:16 ratio tastes different through a fine espresso grind, a medium pour-over, or a coarse French press. Coarser grinds and shorter contact times extract less, so you may want a touch more coffee; finer grinds extract more.
Water and beans shift the result. Water temperature (ideally around 90–96 °C), bean freshness, and roast level all change how much flavour is drawn out. Treat the calculated dose as a reliable baseline, then nudge it by a gram or two.
Weighing beats scooping. A “scoop” of coffee varies with grind and bean, so a kitchen scale gives far more consistent cups than measuring by volume.