How to Use This Cold Brew Calculator
Cold brew is simple to make but easy to get wrong on quantities. This calculator removes the guesswork. First, choose whether you are making concentrate (strong, diluted before drinking) or ready-to-drink cold brew (served straight over ice). Then set how much you want to make and pick your strength. The calculator gives you the exact coffee and water in grams, the dilution ratio, a coarse grind reminder, and a ready-by time so you know exactly when your batch will be done.
Concentrate vs Ready-to-Drink: Which Should You Make?
Cold brew concentrate uses more coffee per unit of water, typically a 1:4 to 1:7 ratio. It is strong and is diluted before drinking, usually 1:1 with water, milk, or poured over ice. Concentrate is the most flexible option: it stores well, takes up less fridge space, and lets you adjust the strength of each glass. Most cold brew makers and recipes default to concentrate.
Ready-to-drink cold brew uses a weaker ratio, around 1:10 to 1:15, so it can be served straight from the jug without dilution. It is simple and convenient if you want to brew a batch and pour it over ice with no extra steps, but it takes up more fridge space and cannot be adjusted later.
Cold Brew Ratio Chart
| Type | Ratio | Result | Dilution |
|---|---|---|---|
| Strong concentrate | 1:4 | Very intense | Dilute 1:1 or more |
| Standard concentrate | 1:5 | Rich, classic | Dilute 1:1 |
| Light concentrate | 1:7 | Milder concentrate | Dilute slightly |
| Ready-to-drink (strong) | 1:10 | Bold, drink straight | None |
| Ready-to-drink (light) | 1:15 | Smooth, drink straight | None |
Why Grind Size Matters for Cold Brew
Cold brew should always use a coarse grind, similar to breadcrumbs or coarse sea salt. Because the coffee steeps for 12 to 18 hours, a fine grind would over-extract and produce a muddy, bitter, gritty brew that is also very difficult to filter. A coarse grind extracts slowly and evenly over the long steep, producing the smooth, sweet, low-acid flavour that cold brew is known for, and it filters cleanly.
How Long to Steep Cold Brew
The ideal steep time is 12 to 18 hours. Steeping in the fridge is slower and more forgiving, so 16 to 18 hours works well. Steeping at room temperature is faster, so 12 to 14 hours is enough. Avoid steeping beyond 24 hours, as this can pull out bitter, woody, and astringent flavours that ruin the smoothness. Once steeped, strain the grounds out promptly. Leaving them in the liquid continues the extraction and will eventually make the brew bitter.