Coffee Ratio Calculator
Dial in the perfect strength — find the grams of coffee for any amount of water at your chosen brew ratio.
Lower means stronger
A 1:15 ratio is strong and full-bodied; 1:18 is milder. The single number sets the strength of every cup.
Works at any scale
One mug or a full carafe — the ratio holds, so the recipe scales cleanly from 250 g of water to 2,000 g.
What is the coffee-to-water ratio?
The single number that sets your strength
The coffee-to-water ratio is the weight of ground coffee compared to the weight of water, written as 1 : X — one part coffee to X parts water. A ratio of 1:16 means 16 grams of water for every gram of coffee. Because it is a ratio, it stays constant whether you brew a single cup or a whole pot, which makes it the most reliable way to get the same strength every time. Weighing both coffee and water on a scale removes the guesswork of scoops and cup markings, where bean density and grind size quietly change how much coffee a spoon actually holds.
Divide the weight of your water by the ratio. That is all there is to it.
Coffee = water ÷ ratioThe ratio is the denominator of the 1 : X expression, so a larger number means more water per gram of coffee and therefore a weaker brew. Keep the water in grams to match the coffee, since one millilitre of water weighs almost exactly one gram.
Suppose you are brewing a 500 g batch and want a balanced 1:16 cup.
Start with your water
500 g of water is the amount you plan to brew.Divide by the ratio
500 ÷ 16 = 31.25.Weigh your coffee
Grind 31.3 g of coffee — round to the nearest tenth your scale shows.
The "golden ratio" sits roughly between 1:15 and 1:18, and according to the Specialty Coffee Association's Golden Cup guidance this range brews coffee that most tasters find balanced. A lower ratio such as 1:15 packs more coffee into the same water for a stronger, heavier cup; a higher ratio such as 1:18 stretches the same beans further for a lighter, more delicate brew. Treat the result as a starting point: brew it, taste it, then nudge the ratio down for more intensity or up for more clarity until the cup is yours.
The arithmetic is exact, but the cup in front of you depends on more than the ratio.
Taste, grind, and method all matter
The ratio sets how much coffee meets the water, but grind size, water temperature, and brew method change how much of that coffee actually dissolves. A coarse French-press grind and a fine espresso grind at the same ratio taste very different. Use the result as a tested baseline rather than a guarantee, and adjust grind and ratio together to taste.