Coffee-to-Water Ratio Calculator
Consistent coffee comes from a consistent ratio of ground coffee to water by weight. This calculator takes your water amount and brew ratio and returns the coffee dose in grams, plus the strength relative to a common 1:16 reference and the equivalent water in cups. Brewing by weight removes the guesswork of scoops, which vary with bean and grind. Pick a ratio between roughly 1:15 and 1:17 for filter coffee, then adjust to taste.
Coffee ratio formula
coffee (g) = water (g) / ratio
brew yield (cups) = water / cup size
strength vs 1:16 = 16 / ratio
tablespoons = coffee (g) / 5 (approx 5 g per level tbsp ground)
Coffee dose equals water divided by the second number of the ratio. A smaller ratio number means more coffee per unit water, hence a stronger brew. The tablespoon figure is approximate because ground density varies.
Worked example
- 480 g water at a 1:16 ratio needs 480 / 16 = 30 g coffee.
- With a 240 g cup, that brews 480 / 240 = 2 cups.
- At 1:16 the strength index is 16 / 16 = 1.00 (the reference).
- Switching to 1:14 raises the index to 1.14, a stronger cup.
- 30 g of coffee is about 6 level tablespoons.
Coffee ratio: frequently asked questions
What does a coffee ratio like 1:16 mean?
A 1:16 ratio means 1 gram of ground coffee for every 16 grams of water. So for 480 grams of water you would use 480 divided by 16 = 30 grams of coffee. A larger second number means a weaker, more diluted brew; a smaller number means a stronger brew.
What ratio should I use?
Filter and pour-over coffee is commonly brewed between 1:15 and 1:17 by weight. Stronger styles use 1:14 or less; lighter cups use 1:18 or more. Taste is personal, so use this as a starting point and adjust the ratio to suit your palate and your beans.
Why measure by weight instead of scoops?
Coffee scoops vary, and ground coffee density differs between beans and grind sizes, so a scoop is an unreliable measure. Weighing both coffee and water in grams gives a repeatable ratio you can dial in and reproduce exactly from one brew to the next.
How many grams of water is a cup?
Water is about 1 gram per millilitre, so a 240 millilitre US cup of water weighs roughly 240 grams. This calculator lets you enter water directly in grams, which equals millilitres for water, so you can scale to any mug or carafe size.
Official sources
- USDA FoodData Central: brewed coffee and water reference data.
- The brew ratio is the standard coffee-mass to water-mass ratio, arithmetic by definition.
Reviewed by the CalculatorHub team, edited by James Graham, 19 June 2026. See our methodology.