Coffee-to-Water Ratio Calculator
Enter your ground-coffee weight and a brew ratio like 1:16 to get exactly how much water to use — in grams and millilitres — for pour-over, French press, espresso or cold brew.
Water needed
288 g (≈ 288 ml)
- Ratio
- 1 : 16
- Ground coffee
- 18 g
- Total brew weight
- 306 g
- Approx. mugs (250 ml)
- 1.2
A 1:N ratio means N grams of water for every gram of coffee, so the water is simply the coffee weight times the ratio. One millilitre of water weighs about one gram, so the grams and millilitres match. Grounds soak up roughly twice their weight in water, so the liquid in your cup is a little less than the water you pour in.
How to use this calculator
Weigh your ground coffee in grams and enter it. Then set your water-to-coffee ratio — the N in 1:N. A ratio of 1:16 means 16 grams of water for every gram of coffee, a balanced strength for filter and pour-over. Use around 1:15 for a stronger filter cup, 1:17–1:18 for a lighter one, 1:12–1:15 for French press, about 1:2 for espresso, and 1:5–1:8 for a cold-brew concentrate. The calculator instantly shows the water you need in grams (which equals millilitres), the total brew weight, and roughly how many 250 ml mugs it makes. Adjust the ratio up to weaken the coffee or down to strengthen it.
How the calculation works
A brew ratio written 1:N means one part coffee to N parts water by weight. The water you need is simply the coffee weight multiplied by the ratio — 20 g of coffee at 1:16 is 20 × 16 = 320 g of water. Because one millilitre of water weighs almost exactly one gram, the grams of water and the millilitres are the same number, so you can pour by weight on a scale or by volume in a jug. The total brew weight is the coffee plus the water. Note that the coffee grounds absorb roughly twice their own weight in water and keep it, so the liquid that ends up in your cup is a little less than the water you started with — the ratio controls strength, not the exact final volume.
Worked example
For a single pour-over you might use 18 g of coffee at a 1:16 ratio. Water = 18 × 16 = 288 g, which is 288 ml, for a total brew weight of 306 g. Want a bigger batch at the same strength? Scale both up: 40 g of coffee at 1:16 needs 640 g (640 ml) of water. The Specialty Coffee Association’s “Golden Cup” guideline of 55 grams of coffee per litre of water is the same as a 1:18.2 ratio — so 55 g of coffee to 1,000 g of water lands right in the sweet spot for filter coffee.
Frequently asked questions
What is a good coffee-to-water ratio?
For filter and pour-over coffee, 1:15 to 1:18 is the usual range, with 1:16 or 1:17 a reliable starting point — the Specialty Coffee Association’s Golden Cup standard works out to about 1:18. French press is often brewed a touch stronger at 1:12 to 1:15, espresso is around 1:2, and cold-brew concentrate is 1:5 to 1:8 before dilution. Start in the middle of the range for your method and adjust from there.
Do I measure water in grams or millilitres?
Either — they are effectively the same for water. One millilitre of water weighs about one gram, so 300 g of water is 300 ml. Weighing on a scale is the most accurate way to hit a ratio because grinds and pours vary, but if you don’t have a scale you can measure the water by volume in a jug and get essentially the same result.
How do I make my coffee stronger or weaker?
Change the ratio. A smaller N (say 1:14 instead of 1:16) means less water per gram of coffee, so the coffee is stronger; a larger N (1:18) means more water and a weaker, lighter cup. Keep the coffee weight the same and only move the ratio, and you’ll change strength without changing how much coffee you make. Many people dial in strength by nudging the ratio by half a point at a time.
Why is the coffee in my cup less than the water I poured?
The grounds soak up and retain water — roughly twice their own weight. So if you pour 300 g of water over 18 g of coffee, the grounds hold back around 35–40 g and you’re left with a bit less in the cup. The ratio still sets the strength correctly; it just means the final drink volume is slightly under the water you added. For espresso and other methods where yield matters, brewers weigh the liquid out instead.
How much coffee do I need for a specific amount of water?
Divide the water by the ratio. If you want 500 ml (500 g) of water at 1:16, you need 500 ÷ 16 ≈ 31 g of coffee. This calculator works from the coffee weight to the water, but the relationship is reversible — pick whichever number you know and solve for the other using water = coffee × ratio.
Does the ratio change for different grind sizes or beans?
The ratio is a starting point, not a fixed rule. Grind size, water temperature, brew time and the beans themselves all affect extraction and taste, so two people using the same 1:16 ratio can get different results. Use the ratio to get in the right ballpark, then fine-tune grind and time to taste — but keep the ratio consistent while you experiment so you’re only changing one thing at a time.