gizmobench

Coffee Ratio Calculator

A brew ratio is coffee to water by weight, so 1:16 is one gram of coffee for every sixteen grams of water: 30 g of coffee is 480 g of water, and the two together are 510 g going into the brewer. Type either weight and this page works out the other, so 1,000 g of water at 1:16 gives 62.5 g of coffee without rearranging anything. Servings scale it two ways and the page makes you say which: the weights are the whole batch and a serving is the batch divided (30 g across 2 servings is 15 g of coffee and 240 g of water each), or the weights are one cup and the batch is that cup multiplied, so twice the servings is twice of both. What it does differently is refuse to pretend about two things. It will not turn a scoop or a tablespoon into grams, because the same spoonful weighs a different amount with every grind and every bean. And it calls the water figure what it is: water going in. Wet grounds keep some of it back, so weigh the brew you poured and the page subtracts (480 g of water in, 415 g of brew out, 65 g held back) and divides to show the ratio in the cup, 1 : 13.83. The arithmetic runs on exact fractions rather than on floating point, so 18.3 g of coffee at 1:16.5 is exactly 301.95 g of water and prints 302 g, where rounding the nearest double gives 301.9, and nothing is uploaded or gated.

1 : 1630 g coffee2 servingsGrams
ratio           1 : 16   by mass
coffee            30 g
water            480 g   30 x 16

per serving       15 g   coffee
                 240 g   water
total in         510 g   coffee plus water

yield is not measured, only what goes in
Weights are

The weights are the whole brew, and a serving is the batch divided by the number of servings.

1 : 16 by mass: 30 g of coffee to 480 g of water, 2 servings of 15 g of coffee and 240 g of water.

The water figure is what goes into the brewer, not what comes out of it: wet grounds keep some of it back. Weigh the brew and enter it under Brewed out to see how much stayed behind.

Three brews, worked

Every weight below is computed by the code that answers the calculator above, so the examples and the tool can never disagree.

  • 1:16, 20 g coffeesolve water
    320 g
  • 1:16, 1,000 g watersolve coffee
    62.5 g
  • 30 g at 1:15 and at 1:17same coffee
    450 g and 510 g
Accuracy. Exact arithmetic by mass: water is coffee times the ratio you picked, and both scale with servings. Everything is weighed in grams because a scoop or a tablespoon of coffee changes with the grind and the bean, so no volume conversion is assumed. It scales what goes in and claims nothing about extraction, strength or taste.

Common questions

How much water do I need for 30 g of coffee?
At 1:16 it is 480 g, because the ratio is coffee to water by weight and 30 x 16 = 480. The page shows that multiplication next to the answer, so the figure is never a black box. Change the ratio and the same 30 g gives 450 g at 1:15 and 510 g at 1:17, which is the third worked example under the calculator.
What is the best coffee to water ratio?
This page will not pick one, because it measures nothing about taste: it does the arithmetic for whichever ratio you type and ranks none of them. Drip and pour-over recipes are commonly written between 1:15 and 1:17, immersion brewers nearer 1:12, and espresso around 1:2. On 30 g of coffee those are 450 g, 510 g and 360 g of water, and 18 g at 1:2 is 36 g.
How much coffee do I need for a litre of water?
Weigh the water rather than measuring it: this page works in grams and does no volume conversion at all. Put the carafe on the scale, and at 1:16, 1,000 g of water is 62.5 g of coffee. At 1:12 the same 1,000 g is 83.3 g of coffee, and split across 4 servings that is 20.8 g of coffee and 250 g of water a cup.
Can I use tablespoons or scoops instead of a scale?
Not here. A tablespoon and a scoop are volumes, and the same spoonful of coffee weighs a different amount with every grind and every bean, so a page that converted one would be inventing a number. Type a volume and the calculator says so instead of guessing, and it names no weight for a spoonful anywhere, not even an approximate one. Grams, milligrams and kilograms are all read, because those are the same unit.
Is the water figure what ends up in my cup?
No, and this is the one place a ratio calculator can mislead you. Every figure here is what goes into the brewer: wet grounds keep some of the water back, so the brew that pours out weighs less than the water that went in. The page will not estimate how much, because that depends on the grind, the bed and the brewer. It does the honest arithmetic instead: weigh the brew, put it in the Brewed out field, and 480 g of water in with 415 g of brew out gives 65 g held back and a ratio in the cup of 1 : 13.83.
What ratio should I use for espresso?
Espresso recipes are written as the dose to the liquid in the cup, and the liquid in the cup is the one thing no calculator can know until you weigh it. Type 18 g at 1:2 and you get 36 g, but that figure is water by the same rule as every other brew here. Weigh the shot and enter it under Brewed out, and the page shows the shortfall and the ratio you actually pulled.
How do I scale a recipe up for more cups?
Two ways, and the page asks which you mean rather than guessing. Leave Weights are on The whole batch and the weights stay put while the servings split them: 30 g of coffee and 480 g of water across 2 servings is 15 g and 240 g each. Switch to One serving and the weights are one cup, so the batch multiplies: 20 g of coffee at 1:16 is 20 g and 320 g for one serving, and 40 g and 640 g for two.
I only know how much water I have. Can it work backwards?
Yes, and it is the same two fields. Type into Water instead of Coffee and the coffee becomes the answer: 1,000 g of water at 1:16 is 62.5 g of coffee, with the division shown beside it. Whichever field you type in last is the one you know, so there is no mode to switch and no second calculator to find.
Does it round the weights?
Only for display, and it says when it has. Weights print to a tenth of a gram, which is what a coffee scale reads, and worked ratios to a hundredth. The arithmetic itself runs on exact fractions rather than floating point, so 18.3 g of coffee at 1:16.5 is exactly 301.95 g of water and prints 302 g, where rounding the nearest double gives 301.9. A figure too small to show at a tenth keeps its digits, down to a thousandth of a gram, rather than printing as a bare zero.
Why has the calculator refused my entry?
Every refusal names the field and what to change. Entries are turned down for a volume unit, a unit that is not a gram, a weight or ratio side of zero, a negative number, text that is not a number, more decimals than the page reads (three for a weight, two for a ratio), a servings count that is not whole, and a weight past the 1,000,000 g it scales. Weighing a brew heavier than everything that went in is refused too, with both totals named, because that is a scale that was not zeroed on the empty jug.
Is my recipe saved or sent anywhere?
It stays in this browser. The ratio, the weight, the servings and anything you measured are remembered locally so the page opens where you left it, and nothing is uploaded or logged. If storage is blocked or full the calculator still works, it simply forgets.

Exact arithmetic by mass: water is coffee times the ratio you picked, and both scale with servings. Everything is weighed in grams because a scoop or a tablespoon of coffee changes with the grind and the bean, so no volume conversion is assumed. It scales what goes in and claims nothing about extraction, strength or taste.