Coffee Ratio Calculator
Calculate coffee and water for any brew ratio and batch size.
What the Coffee Ratio Calculator does
Brew ratio is the weight of water per gram of coffee. It determines strength directly, and because the grounds retain about twice their own weight in water, the coffee that actually reaches the cup is always noticeably less than the water you poured.
Formula
Coffee = Water ÷ RatioWater = Coffee × RatioRetained by grounds ≈ Coffee × 2Yield = Water − Retained
Inputs explained
| Input | Unit | Required | Notes |
|---|---|---|---|
| Start from | one of 3 options | Yes | — |
| Water | g | In some modes | Accepts more than 0. Shown Start from is The amount of water. |
| Coffee | g | In some modes | Accepts more than 0. Shown Start from is The amount of coffee. |
| Number of cups | number | In some modes | Accepts more than 0. Shown Start from is A number of cups. |
| Cup size | ml | In some modes | Accepts more than 0. Shown Start from is A number of cups. |
| Brew ratio — 1 part coffee to | number | Yes | 1:15 is strong, 1:16 standard, 1:18 lighter. Accepts 1 or more. |
| Water retained by the grounds | number | Optional | Grams of water per gram of coffee, typically 2. Accepts 0 or more. |
How to use it
- Choose Start from.
- Enter Brew ratio — 1 part coffee to.
- Fill in the remaining inputs the form shows for your choice.
- Optionally add Water retained by the grounds.
- Select Calculate.
Worked example
A 500 g pour over at a 1:16 ratio.
- Water
- 500 g
- Ratio
- 16
500 ÷ 16 = 31.25 g of coffee. The grounds hold back 62.5 ml, so you get 437.5 ml in the cup.
Frequently asked questions
What ratio should I start with?
1:16 for filter and pour over. Go towards 1:15 for a stronger cup or 1:17 for a lighter one, and change only one variable at a time.
Why is there less coffee than water?
The grounds absorb roughly twice their own weight. Thirty grams of coffee keeps about 60 ml, which is why a 500 g brew yields around 440 ml.