Calculate the perfect coffee-to-water ratio for cold brew concentrate or ready-to-drink batches.
Last updated: March 2026
Cold brew is made by steeping coarsely ground coffee in cold or room-temperature water for 12 to 24 hours. Because it uses time instead of heat for extraction, cold brew is typically lower in acidity and bitterness than hot-brewed coffee. The result is a smooth, naturally sweet beverage that is perfect for serving over ice.
Most cold brew is made as a concentrate using a 1:4 to 1:8 ratio. This concentrate is then diluted with water or milk before serving (commonly 1:1, but varies by taste and bean strength). Alternatively, you can brew a ready-to-drink (RTD) batch using a 1:12 to 1:16 ratio, which can be enjoyed directly with minimal dilution.
Decide whether you want to make concentrate (1:4 to 1:8) which you'll dilute later, or ready-to-drink (1:12 to 1:16) that's ready immediately. Concentrate takes only slightly longer but gives you flexibility—you can use it straight, with water, milk, or in cocktails.
Use coarse-ground beans similar to French press grinds. Coarse grounds minimize sediment and over-extraction during the long soak. Fine grounds can make the concentrate cloudy and bitter. If you have whole beans, use a burr grinder for consistency.
In a clean jar or container, add your coarse grounds and cold water in the calculated ratio. Stir thoroughly to ensure all grounds are wet and there are no dry pockets. Cover the jar loosely—it doesn't need an airtight seal, just protection from dust.
Leave the mixture at room temperature or in the refrigerator for 12–24 hours. Room temperature extracts slightly faster (12–16 hours), while cold steeping (18–24 hours) is slower and more mellow. Taste after 12 hours to see if strength meets your preference.
Pour through a fine mesh strainer or cheesecloth into a clean bottle. If you prefer super clean concentrate, double-filter through paper. Your concentrate keeps 2 weeks refrigerated. For RTD, it's ready to serve now. For concentrate, your preferred dilution ratio depends on taste—start with 1:1 (equal parts concentrate and water/milk), then adjust stronger or weaker.
It's Sunday morning, and you want to prepare cold brew concentrate to last through the week. You'll make a 1:8 concentrate batch (strong enough for dilution with hot or cold liquid) using 300g of premium beans. This will give you roughly 5–6 cups worth of concentrate.
You mix 300g coarse grounds with 2400ml cold water in a large jar Sunday morning. Let it sit 20 hours at room temp, then strain. Each morning Mon–Thu, you pour 50ml concentrate into a cup, add 50ml hot water or milk for a 100ml drink, or 50ml concentrate with 150ml cold milk for an iced latte. Total cost per drink: ~$0.80 vs. $5–6 at a café.
Both make concentrate, but 1:4 is ultra-strong (for hardcore espresso lovers), while 1:8 is more balanced. 1:4 concentrate needs more aggressive dilution (2:1 or 3:1 with milk); 1:8 works better with 1:1 dilution. Start with 1:8 and adjust based on taste.
Cold or room temperature—not hot. Cold brewing uses time instead of heat for extraction. Hot water would give you instant coffee, defeating the purpose. Room temperature extracts slightly faster (12–16h) than cold (18–24h), both taste equally good.
Refrigerated concentrate lasts 2–3 weeks. The acidity and lack of microbes keep it stable. Ready-to-drink (diluted) cold brew lasts 3–5 days. Always store in an airtight bottle to prevent oxidation and flavor degradation.
Yes. Dark roasts often taste smoother and less sharp in cold brew because the long extraction doesn't amplify acidity like hot brewing does. Light roasts showcase origin flavors beautifully. Medium roasts are the safest bet for balanced, crowd-pleasing results.
Over-extraction (steeping >24 hours or using fine grounds) causes bitterness. Too-short steeping (<12 hours) with a high ratio causes sourness. Also check your beans' freshness—stale beans taste sour. Aim for 12–20 hours and use coarse-ground, recently roasted beans.
No. A mason jar, fine mesh strainer, and cheesecloth (optional) are all you need. Some people use French presses or purpose-built cold brew makers for convenience, but they're not required. A jar works just as well.
No. Iced coffee (hot brew poured over ice) uses hot water ratios (1:16 typically). Cold brew uses different ratios because the extraction mechanism is completely different. This calculator is specifically for the long-soak, time-based cold process.
Dilute 1:1 with water or milk for a smooth, balanced cup. Heat the concentrate + hot water for a cozy winter drink. Mix concentrate with sparkling water for a cold brew spritz. Add to cocktails for espresso martinis. Cold brew concentrate is versatile!