Coffee Ratio Calculator

How the coffee to water ratio actually works

A brew ratio is one number: the weight of water divided by the weight of dry coffee. When a recipe says 1:16, it means 16 grams of water for every 1 gram of ground coffee. Everything else in this calculator is arithmetic on that single number, which is exactly why the ratio is the first thing to fix and the last thing to blame. Water is easy here because 1 millilitre of water weighs 1 gram, so a 500 ml kettle pour and 500 g on the scale are the same measurement.

Worked example: 500 g of water, pour over

Pick pour over at 1:16 and enter 500 for the water. The coffee dose is 500 divided by 16, which is 31.25 g, shown as 31.3 g. That water makes about 2.1 cups at the 240 ml US cup size, and the dose works out to roughly 5.7 level tablespoons if you have no scale. Push the strength selector to strong and the ratio becomes 1:14, lifting the dose to 35.7 g; choose mild and it drops to 1:18 and 27.8 g. Those two numbers, 27.8 and 35.7, bracket almost every reasonable filter coffee you will ever make with half a litre of water.

Going the other way: you have 18 g of coffee

Switch the second selector to water from coffee and enter 18. At 1:16 you need 288 g of water, which is a single large mug. This direction is the one to use when you buy pre-portioned beans, when you are finishing a bag, or when your grinder throws a fixed dose. It is also the honest way to plan a single cup: decide the dose you want to taste, then pour to match, rather than filling the mug first and hoping.

The ratio ladder across methods

Different brewers sit at different points on the ladder for physical reasons, not fashion. Percolation methods, where water passes through a bed and leaves, extract efficiently and can afford more water per gram. Immersion methods, where grounds sit in water for minutes, extract more gently and are usually pulled tighter. Espresso is a separate species: it uses a ratio around 1:2 and produces a concentrated liquid measured by what comes out, not what goes in.

Strength and extraction are different levers

Strength is how much dissolved coffee ends up in the cup, and the ratio controls it directly. Extraction is what fraction of each ground particle you managed to dissolve, and it is controlled by grind size, water temperature, agitation and contact time. Confusing the two is the most common home brewing mistake. Coffee that tastes thin and sour is under-extracted, and adding more grounds makes it thicker but still sour; grinding finer or brewing hotter is the actual fix. Coffee that tastes harsh and bitter is over-extracted, and cutting the dose makes it weaker but still bitter; coarsening the grind is the fix. Change one lever at a time and taste after each change.

Scaling up for a crowd

Batch brewing is where the calculator earns its keep. A twelve-cup drip carafe at 240 ml per cup is 2,880 g of water, which at 1:17 needs 169.4 g of coffee — a number nobody guesses correctly with a scoop. A one litre French press at 1:15 wants 66.7 g. For cold brew, 1,000 g of water at 1:8 needs 125 g of coffee and produces a concentrate, so plan on diluting it about one to one before serving, which lands the finished drink near 1:16. When you scale past about a litre, expect to grind marginally coarser, because larger beds slow the flow and push extraction up.

Limitations worth knowing

Grounds keep some of the water. A wet coffee bed retains roughly two grams of liquid per gram of dry coffee, so a 500 g pour over yields around 435 ml in the carafe, not 500. The cups figure here is based on water in, so treat it as a planning number and add ten percent of water if you need an exact serving volume. Espresso is the other caveat: its 1:2 is a yield ratio measured on the liquid leaving the basket, so an 18 g dose targets 36 g in the cup, and the water figure this tool prints is a rough proxy rather than a brew instruction. Finally, every ratio here is a starting point calibrated for medium roasts and average grinders. Brew it, taste it, move one lever, and write down what worked.