Cold Brew Ratio Calculator

Cold brew is the least forgiving brewer to eyeball — too little coffee and you get brown water, too much and you've wasted expensive beans. Get the exact numbers for concentrate or ready-to-drink.

How to use this calculator

First decide what you're making. Concentrate (1:4 to 1:5) is the classic approach: you brew it strong, then dilute it roughly 1:1 with water or milk when serving. It's efficient — one batch stretches twice as far — and it's what most cafés serve. Ready-to-drink (1:8 to 1:10) skips the dilution step entirely: strain it, pour over ice, done. Pick your style, enter your water amount, set the ratio, and the calculator gives you the coffee dose in grams and tablespoons plus serving guidance.

Don't forget that grounds absorb water — about twice their weight. A litre of water with 200 g of coffee yields roughly 600 ml of concentrate, not a litre. Plan your batch size around the yield you want, not the water you start with.

The math, explained

Cold brew ratios work exactly like hot brew ratios: coffee equals water divided by the ratio number. One litre (1000 ml) of water at 1:4 needs 250 g of coffee; at 1:5 it needs 200 g. For ready-to-drink at 1:8, that same litre needs 125 g. The slider is limited to 1:4–1:10 because anything outside that range is either undrinkable sludge or flavored water.

Dilution is the second half of the math. Concentrate brewed at 1:4 and diluted 1:1 with water lands at an effective 1:8 drinking strength — right in the normal coffee range. Dilute with milk instead and you get a creamier, slightly weaker cup. Start 1:1 and adjust: more water for a lighter cup, less for a stronger one.

Tips for better cold brew

Grind coarse — coarser than you think. Cold brew steeps for 12–24 hours, so fine grounds over-extract and turn bitter, and they clog filters. Aim for raw-sugar-sized particles. If your cold brew tastes harsh, your grind is almost certainly too fine.

Steep 12–16 hours at room temperature. Longer isn't better: past ~18 hours you extract woody, astringent flavors. Taste at 12 hours; if it's thin, give it more time, but set a timer so you don't forget it.

Filter twice. Strain through a fine-mesh sieve first to catch the bulk of the grounds, then through a paper coffee filter or cheesecloth for a clean cup. Skipping the second pass leaves sediment that keeps extracting and turns the batch bitter in the fridge.

Bean choice matters. Chocolatey, nutty coffees — think Brazil or Colombia naturals — make the crowd-pleasing cold brew. Bright, acidic Ethiopians can taste odd cold. And since you're using a lot of coffee per batch, this is the perfect excuse to brew it with fresh-roasted beans from Raven Horse Co.