Cold brew without guesswork

Choose your strength

For a concentrate that you dilute later, start around 1:6 coffee to water by weight, for example 100 g of coffee and 600 g of water. For ready-to-drink cold brew, try 1:12 to 1:15. Use the calculator to scale either recipe to your jar.

Concentrate or ready to drink

A concentrate saves fridge space and lets you adjust each glass. Ready-to-drink cold brew is convenient once you know the strength you like. Whichever you choose, use the same ratio each time so the batches can be compared.

Use a coarse grind

A coarse grind, similar to French press, makes filtering easier and reduces the muddy texture that comes from too many fine particles. Stir once after adding the water so all the grounds are wet.

Steep for 12 to 18 hours

Steep in the fridge or at cool room temperature, then filter. Room temperature extracts faster, so start nearer 12 hours there and nearer 18 in the fridge. Longer is not always better: taste a small sample before extending the time.

Filter patiently

Let the grounds drain without pressing them hard. Pressing can push fine particles and bitter flavours into the drink. Pouring through a paper filter after a mesh filter makes a cleaner cup if the brew feels muddy.

Dilute and store

Dilute concentrate with water or milk to taste. A 1:6 concentrate mixed one to one with water drinks roughly like a 1:12 brew. The calculator below treats the concentrate as if it held all its brew water, which ignores the water the grounds soaked up, so read the result as a close estimate.

Store filtered cold brew in a sealed jar in the fridge and drink it within about a week, while it still tastes fresh.

Fix a batch that tastes wrong

Sour or thin cold brew can need more time, a finer grind, or less dilution. Bitter, woody cold brew can need less time, a coarser grind, or a cleaner filter. Change one variable on the next batch and keep the rest fixed.

Cold hides aroma and acidity, so taste a small sample at a slightly warmer temperature before deciding the batch has no flavour.

Keep the batch repeatable

Record the ratio, grind, steep time, and the dilution you liked in Roastbook. A large batch then depends on a saved recipe instead of memory.