Enter your desired brew size, pick a brew strength (Mild to Concentrate), and choose your yield unit — the Cold Brew Ratio Calculator tells you exactly how much coffee grounds and water you need. You also get a recommended brew time and grind size tip so your batch comes out perfectly every time.
Coffee Grounds Needed
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Water Needed
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Water (Cups)
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Recommended Brew Time
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Your Coffee:Water Ratio
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The most popular cold brew ratio is 1:10 (1 gram of coffee per 10 ml of water), which produces a balanced, drinkable concentrate. For a lighter brew try 1:12, and for a strong concentrate meant to be diluted with water or milk, go as low as 1:4 or 1:5.
Cold brew is coffee steeped in cool or room-temperature water for 8–24 hours, rather than brewed with hot water. Because no heat is involved, the extraction is slower and produces a naturally sweeter, less acidic, and smoother cup compared to hot drip or espresso methods.
Cold brew is typically higher in caffeine per ounce than hot drip coffee because it uses a higher coffee-to-water ratio and a long steep time. An 8 oz serving can contain 150–200 mg of caffeine, versus roughly 95 mg in a standard drip coffee. Diluting a concentrate will lower the caffeine level.
Yes — cold brew is generally 60–70% less acidic than hot-brewed coffee. The absence of heat during extraction means fewer acidic compounds are released from the grounds, making it a gentler option for people with sensitive stomachs.
A typical steep time is 12–18 hours in the fridge (or 8–12 hours at room temperature). Steeping for less than 8 hours can result in weak, under-extracted coffee, while going beyond 24 hours may produce bitter or over-extracted flavours. Coarser grinds tolerate longer steeps better.
A coarse grind — similar to coarse sea salt — is ideal for cold brew. Finer grinds extract too quickly, can turn bitter, and are much harder to filter out. If you only have pre-ground drip coffee, reduce your steep time slightly to compensate.
Divide the total volume of water (in ml) by your chosen ratio to get the grams of coffee needed. For example, for 1 litre of water at a 1:10 ratio: 1000 ml ÷ 10 = 100 g of coffee. Keep in mind that coffee grounds absorb some water (roughly 20% of your water volume), so add extra water if you want a specific final yield.
Both work well. Room-temperature brewing is faster (8–12 hours) and can produce slightly fuller flavour, but the brew should be refrigerated once done. Fridge brewing takes longer (16–24 hours) but keeps the coffee clean and food-safe throughout the process. Always store finished cold brew in the fridge and consume within 2 weeks.