Making cold brew concentrate is the smartest way to brew at home: one batch gives you a week of coffee, and you control the strength of every glass. The only trick is getting the ratio right going in, and the dilution right coming out. Here is exactly how I do it.
Why brew a concentrate instead of ready-to-drink?
A concentrate stores better, takes up less fridge space, and lets you make hot or iced coffee on demand by adding water or milk. It is the most flexible format — and it is the base for most cafe iced coffees too.
The concentrate ratio
For a true concentrate, use a coffee-to-water ratio around 1:4 to 1:5 by weight — much stronger than a ready-to-drink brew. For example, 200g of coarse coffee to 800g–1000g of water. If you want it ready-to-drink straight from the jug, go closer to 1:8. Our full breakdown lives in the cold brew ratio guide.
Step by step
- Grind coarse. Fine grounds make a muddy, over-extracted, bitter concentrate. See cold brew grind size.
- Combine and stir. Add coffee and cold filtered water, stir to wet all the grounds.
- Steep 14–18 hours. Room temperature or in the fridge. Longer for a stronger, but never bitter, result.
- Filter twice. Once through a mesh, once through a paper filter or cloth for a clean cup.
- Refrigerate. The concentrate keeps well — details in how long cold brew lasts.
How to dilute cold brew concentrate
This is where people go wrong. Start with a 1:1 ratio of concentrate to water (or milk) over ice, taste, and adjust. Some like it 1:2 for a lighter cup. For a latte, use the concentrate undiluted and top with milk. Because you are diluting, the caffeine per glass depends on how heavy-handed you are — see cold brew caffeine.
Making it without a dedicated maker
A large jar and a fine strainer work fine. But a purpose-built brewer with a filter basket makes filtering far less messy — compare them in the best cold brew maker guide, or skip brewing entirely with a store-bought concentrate. Bean choice matters too: coffee beans for cold brew.
Frequently asked questions
What is the best ratio for cold brew concentrate?
Around 1:4 to 1:5 coffee to water by weight for a true concentrate you will dilute before drinking.
How do I dilute cold brew concentrate?
Start 1:1 with water or milk over ice, then adjust to taste. Use it undiluted for lattes.
How long does concentrate last?
Typically one to two weeks refrigerated — longer than ready-to-drink cold brew because it is stronger.
