How to Make Cold Brew at Home: Ratios, Grind and Mistakes to Avoid

Cold brew is the smoothest, sweetest, lowest-acid coffee you can make — and also the easiest. No machine, no thermometer, no barista skills. Just coffee, water, a jar and some patience. Here’s the recipe that works every single time.

What cold brew actually is (and what it isn’t)

Cold brew is coffee steeped in cold or room-temperature water for 12 to 24 hours. Because no heat is involved, far fewer acidic and bitter compounds are extracted, and you get a smooth concentrate you dilute later with water or milk.

Important: cold brew is not iced coffee. Iced coffee is hot-brewed coffee cooled down fast. Cold brew never meets heat at all. The taste difference is night and day.

The right cold brew ratio

Two foolproof starting points:

• Concentrate (1:8): 100 g of coffee to 800 ml of water. Dilute 1:1 with water or milk when serving. Best if you batch-bottle for the week.
• Drink-as-is (1:15): 60 g of coffee to 900 ml of water. Pour over ice and enjoy.

First time? Go 1:10 — 80 g of coffee to 800 ml of water. It’s the middle ground that’s almost impossible to mess up.

Step by step

1. Grind coarse. This is the make-or-break step: colder, longer extraction needs a grind coarser than French press — think chunky sea salt. Fine grounds give you a muddy, bitter, silty mess.
2. Combine coffee and water in a glass jar or pitcher. Stir well so every ground is saturated; dry clumps mean under-extraction.
3. Cover and wait. 16-18 hours at room temperature, or 20-24 hours in the fridge. Overshooting by a couple of hours is fine — cold brew is forgiving.
4. Strain twice. First through a mesh sieve to catch the grounds, then through a paper or cloth filter. This second pass is what separates a clean glass from a gritty one.
5. Store and enjoy. Keeps 7-10 days in a sealed bottle in the fridge.

Mistakes that ruin cold brew

• Grinding too fine. The number-one error: bitterness, sediment and a clogged filter.
• Using stale coffee. Cold extraction doesn’t hide staleness — it exposes it. Use beans roasted within the last 4-6 weeks.
• Stopping early. Six or eight hours gives you a thin, flat, under-extracted drink. Wait the full time.
• Skipping the second strain. Fines keep extracting in the bottle and turn the batch harsh by day three.
• Heavily chlorinated tap water. If the water tastes bad, the brew will too. A basic carbon filter fixes it.

Best beans for cold brew

Almost anything works, but some shortcuts:

• Medium or medium-dark roasts deliver chocolate and caramel body that stands up to milk.
• Brazil or Colombia single origins: nutty, cocoa, sweet — cold brew classics.
• Light-roast African coffees shine drunk black over ice, though some of their sparkle fades.

Avoid supermarket dark roasts: burnt bitterness dominates in cold extraction.

Variations worth trying

• With milk: dilute concentrate 1:1 with milk or oat milk, add a drop of vanilla.
• Cold brew tonic: 60 ml concentrate, tonic water, orange slice. Fancy and refreshing.
• Nitro at home: shake a jar of cold brew hard for 30 seconds and pour — tiny bubbles, creamy mouthfeel, no nitro charger needed.

Quick answers

How much caffeine? A properly made glass of cold brew has as much or more caffeine than drip coffee, because the concentrate is dosed generously. Want less? Dilute more.

Can I speed it up? Occasional agitation helps extraction a little, but the whole point is that it makes itself.

Can you heat it? Yes — hot-diluted cold brew tastes like a clean drip coffee. Weird, but good.

Bottom line

Making cold brew at home is the best effort-to-reward ratio in coffee: coarse grind, 1:8 to 1:15 ratio, 16-24 hours, double strain. Make a batch on Sunday and you’ve got perfect iced coffee all week.