Coffee to Water Ratio Calculator
Pick a brew method, enter your coffee or your water, and get the other side of the ratio.
Grams and millilitres of water are interchangeable — a scale is far more accurate than a jug either way.
What a brew ratio means
A ratio of 1:16 means one gram of ground coffee for every sixteen grams of water — 20 g of coffee to 320 g of water. It is the single most useful number in brewing, because it fixes strength before you touch grind size or technique. Two people using the same ratio, water and beans will make recognisably similar cups; two people guessing with scoops will not.
Why methods differ
Percolation methods like V60 and Chemex run comfortably at 1:15 to 1:17 — the classic filter-strength cup. Immersion methods such as French press and AeroPress are often brewed slightly tighter, around 1:14 to 1:15, because some water stays trapped in the bed. A moka pot at roughly 1:10 lands between filter and espresso, cold brew concentrate at 1:8 is made to be diluted, and espresso at 1:2 is its own world — see the espresso ratio calculator for dose and yield.
Adjusting to taste
Move the ratio for strength, the grind for extraction. If the cup tastes weak and thin, tighten the ratio (1:15 instead of 1:16); if it is muddy and heavy, loosen it. If it tastes sour, grind finer or brew hotter; bitter, coarser or cooler. Change one variable at a time, keep the rest fixed, and taste after each change — that is dialling in, and it works faster than any amount of theory.
How it works
Choosing a brew method fills in its ratio: 1:16 for V60 and Chemex, 1:15 for AeroPress and French press, 1:10 for a moka pot, 1:8 for cold brew concentrate and 1:2 for espresso. You can type any ratio over the top of it. The calculator then does one of two sums. Going from coffee to water, it multiplies the coffee by the ratio and rounds to the nearest gram. Going from water to coffee, it divides the water by the ratio and rounds to a tenth of a gram. Water in grams and in millilitres is treated as the same thing.
A worked example
Say you are brewing 500 g of water in a cafetière and want to know how much coffee to weigh out.
| Water | 500 g |
| Ratio (French press preset) | 1:15 |
| Coffee (500 ÷ 15 = 33.33…, rounded) | 33.3 g |
| The same water at 1:16 (500 ÷ 16 = 31.25, rounded) | 31.3 g |
Two grams sounds like nothing, but moving from 1:16 to 1:15 puts roughly 7% more coffee into the same water, and that is a difference you can taste. It is also why the scale matters more than the exact starting ratio: whichever number you choose, you can repeat it tomorrow and adjust from a known point.
Frequently asked questions
What is the golden ratio for coffee?
Usually a filter ratio somewhere between about 1:15 and 1:18 — roughly 55 to 67 g of coffee per litre of water. It is a range rather than a single number, because beans, roast and personal taste all move it. 1:16 is a sensible middle to start from: brew it, then tighten the ratio if the cup is thin, or loosen it if it is heavy.
How many grams of coffee per cup?
It depends on the cup, which is why a ratio is more useful than a scoop. For 250 g of water, 1:16 gives 15.6 g of coffee and 1:15 gives 16.7 g, so somewhere around 15 to 17 g is a good starting point for a mug of filter. For a bigger mug, enter the water you actually pour and let the ratio scale the coffee with it.
Is a 1:16 ratio coffee to water or water to coffee?
Coffee to water: one part coffee to sixteen parts water, by weight. Some recipes write it the other way round as 16:1, and some give a dose per litre instead. To convert, divide 1,000 by the ratio — 1:16 is 62.5 g of coffee per litre — or divide 1,000 by the grams per litre to get back to a ratio.
Does the bloom water count towards the ratio?
Yes. For pour-over, the ratio covers all the water that goes through the coffee, bloom included, so a recipe that blooms with 40 g and then pours to 320 g uses 320 g in total. The cup holds a little less, because the wet grounds keep some back. Espresso is counted differently: its ratio compares the dry dose with the liquid in the cup, not the water that went in.
What ratio should I use for a cafetière?
Around 1:15 is a good starting point, and it is what the French press preset uses. Immersion brewing is often run a little tighter than pour-over, from about 1:14 to 1:15, because some water stays trapped in the grounds. If the cup tastes weak, move towards 1:14 before changing anything else; if it tastes heavy, try 1:16.
This calculator is built into Kohii — The Barista Log, along with brew logging, dial-in history and bean freshness tracking. Offline, no account.
More coffee tools
- Espresso Ratio CalculatorDose, yield, ratio — enter any two and solve the third.
- Coffee Freshness CalculatorRoast date in, peak window out — for espresso and filter.
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