What is the coffee-to-water ratio for cold brew?

It depends on whether you're making concentrate or ready-to-drink coffee. For a concentrate you dilute later, use about 1:8 by weight — roughly 1 cup of coarse grounds to 4 cups of water. To drink straight from the jar, use about 1:15, closer to hot-coffee strength. A common starting point is 1 cup coffee to 4 cups water for concentrate, then cut it 1:1 with water or milk in the glass. Use the coffee-to-water ratio calculator to scale any batch.

How do you make cold brew coffee, step by step?

Coarsely grind your coffee and put it in a jar or pitcher. Add cold or room-temperature water and stir until every ground is wet. Cover it and leave it on the counter or in the fridge for 12 to 24 hours. Then strain it — through the mesh basket of a cold brew maker, or a fine sieve lined with a paper filter or cheesecloth over a clean jar. Squeeze or press gently to get the last of it, then store the strained coffee in the fridge. That's the whole process: no heat, no timing during the day, just mix, wait, and strain.

What grind size should you use for cold brew?

A coarse grind — like coarse sea salt or breadcrumbs, the same as for a French press. A long steep needs a coarse grind: fine grounds over-extract and turn the batch bitter, and they slip through the filter to leave sludge. A burr grinder set coarse gives the uniform, chunky grounds cold brew needs; a blade grinder's mix of dust and chunks is the usual cause of muddy, silty cold brew. See the grind size guide.

How long should cold brew steep?

Between 12 and 24 hours. Around 12–16 hours gives a lighter, brighter result; 18–24 hours gives a stronger, rounder concentrate. Past about 24 hours the gain is small and it can start tasting woody, so strain it by then. Steeping in the fridge is slightly slower and cleaner-tasting than steeping at room temperature; both work. The steep time is the one big lever — if your cold brew is weak, steep longer or use more coffee rather than reaching for finer grounds.

How long does cold brew last in the fridge?

Strained cold brew keeps well for about a week to 10 days in a sealed container in the fridge — far longer than hot coffee, which is part of the appeal of making a batch. Concentrate keeps a bit longer than diluted cold brew because there's less water in it. Store it strained (don't leave it sitting on the grounds, or it keeps extracting and turns bitter), and dilute each glass to taste as you go.

Why is my cold brew weak or bitter?

Weak cold brew almost always means too little coffee or too short a steep — use more grounds (a lower ratio) or leave it 18–24 hours rather than grinding finer, which just adds bitterness and sludge. Bitter or muddy cold brew usually means the grind was too fine or it over-steeped past a day. Use a coarse, even burr grind, keep the steep in the 12–24 hour window, and strain promptly once it's done.

How to Make Cold Brew Coffee: Ratio, Grind, and Steep Time

What you need

A jar, pitcher, or cold brew maker — anything that holds the batch and can be covered. A dedicated maker just adds a built-in mesh filter.
A burr grinder set coarse — the single most important thing for clean, non-bitter cold brew (why burr beats blade).
A way to strain — a cold brew maker’s basket, or a fine sieve lined with a paper filter or cheesecloth.
No kettle, no scale required (though a scale helps the first few times).

Concentrate or ready-to-drink?

This is the one decision to make up front, because it sets your ratio:

Concentrate — about 1:8. Strong and space-saving. You dilute each glass 1:1 with water, milk, or over ice. Best if you drink cold brew daily or want it to keep.
Ready-to-drink — about 1:15. Closer to hot-coffee strength, poured straight from the jar. Simpler, but takes more fridge space per serving.

Most people make concentrate. Calculate either.

The method

Coarsely grind your coffee — like sea salt (grind size guide). This is non-negotiable for a long steep.
Combine grounds and cold or room-temperature water in the jar, and stir until every ground is wet.
Cover and steep 12–24 hours — counter or fridge, your choice.
Strain through the maker’s basket, or a sieve lined with a paper filter or cheesecloth, into a clean jar. Press gently to get the last of it.
Store strained in the fridge; dilute each glass to taste.

Fixing a bad batch

Problem	Cause	Fix
Weak, watery	Too little coffee, or steep too short	More grounds (lower ratio); steep 18–24 hrs
Bitter, harsh	Over-steeped, or grind too fine	Strain by 24 hrs; grind coarser
Muddy, silty	Grind too fine, or blade-ground dust	Coarse, uniform burr grind; strain through paper
Sour, sharp	Under-extracted (steep too short)	Steep longer, or use warmer water

Why cold brew

It’s the lowest-effort brew there is and the most forgiving: no heat, no pour technique, no four-minute timer — you mix it and walk away. The cold, slow extraction pulls fewer of the acidic and bitter compounds that hot water does, so cold brew tastes smoother and less acidic than iced hot coffee, and a single batch of concentrate keeps for about a week. The trade-offs are the wait and the strain step. Get a coarse-capable burr grinder and it’s the easiest coffee habit to keep. For a hot brew with a similar coarse grind, see how to use a French press.