Cold Brew Coffee Ratio Calculator

The Cold Brew Ratio Calculator That Actually Accounts for Absorption

Cold brew is the most forgiving coffee you can make — coarse grounds, cold water, time — but the ratios trip everyone up, because coffee grounds soak up a surprising amount of water. This cold brew calculator gives you the exact coffee dose for your jar, the concentrate you will actually pour off after the grounds drink their share, and how many glasses that makes once you dilute.

Enter your vessel size, pick a strength from intense concentrate to a lighter ready-to-drink brew, choose a steep time, and set how you like to dilute. The numbers update instantly, so you can scale from a single mason jar to a three-liter batch without guessing. Whether you brew in a mason jar, a French press, a dedicated Toddy, or a filter bag, the math is the same — this tool just makes it fast.

Concentrate vs ready-to-drink cold brew

There are two ways to make cold brew, and the ratio is the only real difference. A concentrate (around 1:4 to 1:5 coffee to water) is brewed strong, then diluted to taste with water, milk or over ice — it stores well and stretches further. A ready-to-drink brew (around 1:8 to 1:12) is sipped as-is with no dilution. Concentrate is the smarter choice for most people: it keeps for up to two weeks in the fridge, takes up less space, and lets each glass be exactly as strong as you want.

Why absorption changes your yield

Here is the detail most calculators ignore: coffee grounds retain roughly twice their own weight in water. Steep 200 g of coffee and you lose around 400 g of liquid to the spent grounds when you strain. If you plan for a full liter of concentrate and forget this, you come up short every time. This calculator subtracts that absorption so the “concentrate yield” number is what genuinely ends up in your bottle — then it multiplies by your dilution to show real servings.

How long to steep cold brew

Steep time controls strength and smoothness alongside the ratio:

Cold water extracts slowly and gently, which is exactly why cold brew tastes so smooth and low in acidity — the harsh, sour compounds that hot water pulls quickly never get the chance to dissolve.

Grind coarse, strain twice

Cold brew wants the coarsest grind you can make — think raw sugar or bigger. Too fine and you get a muddy, over-extracted, hard-to-filter mess. Strain through a mesh or cloth first, then through a paper filter for a clean finish. Store the concentrate in a sealed bottle in the fridge and it will stay fresh for a week or two, ready to pour over ice in seconds.

Dial your cup from the concentrate

Once you have concentrate, every glass is a two-second decision: half concentrate, half water or milk over ice is the classic starting point, and this calculator does that math for your batch. Want it stronger? Dilute less. Making iced lattes? Cut the concentrate with cold milk instead of water. It is the most flexible coffee in your fridge. For the full step-by-step method, filtering tips and troubleshooting, read the complete home cold brew guide, then use this calculator every time you start a new batch.