How to Make Cold Brew Coffee at Home (Concentrate Method)

Cold brew has a reputation for being fussy, and it is the exact opposite. It is the most forgiving coffee you can make: you cannot scorch it, there is no pour technique, and no thermometer. You steep coarse grounds in cold water, wait, and strain. The only two things that decide whether a batch is great or watery-and-bitter are the two most people never actually measure, the ratio and the steep time. Nail those and everything else is margin.

This is the concentrate method: brew it strong, keep it in the fridge, and dilute each glass to taste. It is the most flexible and space-efficient way to do it, and it is how most bottled cold brew is made.

The only recipe you need

Two roads lead to the same glass. Brew a concentrate and dilute it later, or brew it ready-to-drink and pour it straight. The concentrate route wins on flexibility and fridge space, so start there.

The National Coffee Association points to roughly 1 gram of coffee to 4 to 5 grams of water for a strong concentrate; 1:8 is a gentler starting point that still dilutes down nicely. Whatever you pick, weigh it, because a scoop lies. Our cold brew ratio calculator turns any ratio into exact grams for your jar size.

The dial-in matrix

Here is the part most how-tos skip: ratio and time are two separate knobs, and you can steer the result on purpose. Read this as what happens when you turn each one:

The NCA notes cold brew typically needs about 12 hours of contact, and that times run 12 to 18-plus hours overnight. Past roughly 18 hours in a strong ratio you start pulling woody, papery notes. Colder water extracts more slowly, so a fridge steep wants the full window; room temperature is faster but less clean.

What most people get wrong: it is time and ratio, not the beans

Here is a claim you can test this week. If your cold brew is disappointing, do not change beans first, change the ratio and the clock. Over-steeping ruins more batches than under-steeping, because people leave the jar in the fridge "a bit longer to make it stronger." Strength comes from the ratio, not from extra hours; extra hours past the window mostly just add bitterness and a dry, woody edge. Weak brew means use more coffee, not more time. Bitter brew means steep less, do not reach for a coarser grind first.

That is the falsifiable version: keep your beans identical and brew two jars at the same 1:8 ratio, pulling one at 16 hours and one at 28. The 28-hour jar will not be stronger, it will be more bitter. The bean was never the problem.

Step by step

1. Grind coarse, like rock salt, the same as French press. Fine grounds slip through the filter and over-extract into mud. A burr grinder keeps the grind even.
2. Combine and stir. Add the grounds to your jar or cold brew maker, pour in cold filtered water, and stir until every ground is wet, since dry clumps brew unevenly.
3. Steep in the fridge, 12 to 18 hours, covered. Set a timer so an overnight steep does not quietly become a 24-hour one.
4. Strain once, cleanly. Lift out the filter basket, or pour through a fine mesh (add a paper filter if you want it crystal clear). Do not squeeze the grounds, which presses bitterness back in.
5. Bottle the concentrate and refrigerate it.
6. Dilute to taste, about 1:1 with water or milk over ice. Start there and adjust.

Troubleshooting

Match what you actually taste to the real cause before you blame the beans:

Storage, serving, and caffeine

Keep the concentrate sealed in the fridge and it stays good for around a week or more; once you dilute a portion, it is best within a few days. Because it is cold and low in the acids hot water pulls out, it is fairly stable, but it does slowly fade, so brew what you will actually drink.

On strength: cold brew is often assumed to be a caffeine bomb. A properly diluted 16 oz cup lands around 200 mg of caffeine, versus roughly 165 mg for the same-size iced coffee, and that gap comes from the strong ratio and long steep, not from the cold water (which actually extracts caffeine less efficiently). Undiluted concentrate is far stronger, which is exactly why you dilute it.

One thing cold brew is not: dramatically lower in acid. A 2018 study found the pH of hot and cold brews comparable; cold brew tastes smoother because hot water extracts more of the sharp acid compounds, not because the pH is far lower. It is mellow, not acid-free. We dug into that in cold brew vs iced coffee.

Gear and beans

You do not need much. Any jar with a fine strainer works, but a purpose-made maker removes the mess:

• Cheapest tidy option: the OXO Compact Cold Brew drains the concentrate off the grounds with one switch.
• Most fridge-flexible: the Takeya Deluxe is leak-proof and steeps on its side. See how the two stack up in our Takeya vs OXO head-to-head.
• Pour-and-go: the Hario Mizudashi lives in the fridge door.
• Dirt cheap: a mason jar kit.

For beans, cold brew rewards bold, chocolatey, dark-to-medium roasts, and our best beans for cold brew has the picks. Browse the full lineup on our cold brew makers guide.

Get the ratio and the clock right and cold brew is nearly impossible to mess up. Everything else is just your taste.