Cold brew calculator
Tell us your jar size and how you like it. We'll work out the coffee, how much cold brew you'll actually get, how many drinks that makes and when to strain it.
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All 6 tools →How this cold brew calculator works
Cold brew is ground coffee steeped in cold or room-temperature water for many hours, then strained. The calculator divides your water by the ratio to get grams of coffee, then subtracts what the grounds soak up. Coarse grounds hold on to roughly 2 grams of water for every gram of coffee, which is why a 1-litre jar never gives you a full litre back. Strong concentrates lose the most, because there are more grounds in the jar.
Concentrate vs ready-to-drink
Concentrate (about 1:4 to 1:6) is brewed strong so you can dilute it with water or milk and pour it over ice without it going weak. It takes less fridge space and is flexible: a splash in milk for a creamy iced latte, or 1:1 with water for a classic glass.
Ready-to-drink (about 1:8 to 1:12) is brewed at drinking strength. It's simpler, but ice will dilute it, so many people brew it a notch stronger (1:8) if they serve it over a full glass of ice.
| Style | Ratio (by weight) | For 1 litre water | Serve |
|---|---|---|---|
| Strong concentrate | 1:4 | 250 g coffee | 1 part to 2 parts water/milk |
| Classic concentrate | 1:5 | 200 g coffee | 1:1 with water or milk |
| Mellow concentrate | 1:6 | 167 g coffee | 1:1, or a little stronger |
| Bold ready-to-drink | 1:8 | 125 g coffee | Over ice, as is |
| Classic ready-to-drink | 1:10 | 100 g coffee | As is, light ice |
How long should cold brew steep?
Most recipes steep for 12 to 18 hours at room temperature or 16 to 24 hours in the fridge, because cold water extracts more slowly. Shorter steeps taste lighter and brighter; longer steeps taste deeper and more chocolatey. Go much past a day and cold brew can taste woody or flat. Enter your start time and the calculator gives you a strain-by window, so a jar started after dinner is ready for tomorrow's afternoon iced coffee.
Stir gently once after adding water so every ground is wet, then leave it alone. Dry pockets of coffee floating on top are the most common cause of weak cold brew.
Grind, beans and straining
- Grind coarse, like rough sea salt. Fine grounds make muddy cold brew that is hard to strain. See our grind size chart.
- Medium and dark roasts give the classic smooth, chocolatey cold brew. Light roasts work too and taste fruitier.
- Strain twice: first through a sieve, then through a paper filter or cloth for a clean cup.
How to serve cold brew
Concentrate is flexible, so taste as you go. A few popular ways to serve it:
- Classic iced: equal parts concentrate and cold water over plenty of ice.
- Creamy: equal parts concentrate and milk (or oat milk), with a spoonful of homemade syrup.
- Hot cold brew: top concentrate up with just-boiled water for a smooth, low-bitterness hot cup. Great on cold mornings.
- Café-style: ready-to-drink cold brew with a cap of vanilla sweet cream cold foam.
Ice melts into your drink, so if you like a strong glass, dilute a little less (the "2:1 bolder" option) or freeze cold brew in an ice cube tray so the cubes add coffee instead of water.
Storage and safety
Keep strained cold brew in a clean, sealed jar in the fridge. As general guidance, concentrate is at its best within about a week and is commonly kept for up to two; diluted cold brew is best within a few days to a week. If it smells sour or looks cloudy, pour it out. If you steep on the counter, move it to the fridge as soon as you strain it.
Want to go further? Read our full cold brew ratio guide, then top your glass with homemade cold foam.
Related guides
Questions people ask
What is the best ratio for cold brew?
For concentrate, 1:5 coffee to water by weight is a reliable starting point (200 g coffee per litre). For ready-to-drink cold brew, try 1:8 to 1:10.
How much coffee do I need for 4 cups of cold brew?
4 cups of water (about 946 ml) at 1:5 needs about 190 g of coarse coffee for concentrate. At 1:8 for ready-to-drink, use about 118 g.
Can cold brew steep too long?
Yes. After roughly 24 hours it can start to taste woody, bitter or flat. Most people strain between 12 and 24 hours depending on temperature.
Should cold brew steep in the fridge or on the counter?
Both work. Room temperature extracts faster (about 12 to 18 hours). The fridge is slower (about 16 to 24 hours) and many people prefer it for food-safety peace of mind. Either way, refrigerate after straining.
Does cold brew have more caffeine?
Concentrate usually has more caffeine per ounce because it is brewed strong, but once diluted a glass of cold brew is often in a similar range to hot brewed coffee. It varies a lot by recipe.
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