Cold brew is made by steeping coarse coffee grounds in room-temperature water for 12 to 24 hours, then straining out the grounds
The long soak extracts flavor slowly and produces a concentrate that is smoother and less acidic than hot-brewed coffee. You do not need special equipment — a jar, a filter, and patience are enough. The concentrate keeps in the refrigerator for up to two weeks, so you can make a batch once and drink from it for days.
The main variables that change the taste are the coffee-to-water ratio, the steeping time, the grind size, and how you dilute the concentrate. Getting these right takes one or two batches to dial in, but the process itself is forgiving — it is hard to ruin cold brew by accident.
Key Takeaways
- Use a 1:4 or 1:5 ratio of coffee to water by weight (for example, 50 grams of coffee to 200 grams of water), and adjust the ratio up or down depending on how strong you like it.
- Coarse grounds are essential because fine grounds will clog your filter and make the concentrate muddy; use the coarse setting on a burr grinder or ask your coffee shop to grind coarse.
- Steeping for 12 hours produces a milder concentrate; 18 to 24 hours produces a stronger one — taste it at 12 hours and decide whether to strain it then or wait longer.
- Dilute the concentrate with water, milk, or both before drinking; a 1:1 ratio of concentrate to water is a common starting point, but adjust to your taste.
- Store the strained concentrate in a sealed container in the refrigerator, where it will keep for two weeks or longer.
The coffee-to-water ratio and how to measure it
The ratio of coffee to water determines how strong the final concentrate is. A 1:4 ratio (one part coffee to four parts water by weight) produces a concentrate you will dilute 1:1 with water or milk. A 1:5 ratio produces a milder concentrate that you can drink closer to 1:2 or even straight with ice.
Weigh both the coffee and the water if you have a kitchen scale — this is more accurate than measuring by volume. If you do not have a scale, use a ratio of roughly one part coffee to four parts water by volume (for example, one cup of grounds to four cups of water), but know that the strength will vary slightly depending on how densely you pack the grounds.
Start with 1:4 if you like strong coffee, or 1:5 if you prefer it milder. After your first batch, taste the concentrate and adjust the ratio for the next one. If it tastes weak, use more coffee next time. If it tastes too bitter or harsh, use less coffee or shorten the steeping time.
Choosing the right grind size
Coarse grounds are non-negotiable for cold brew. Fine or medium grounds will pass through most filters and cloud the concentrate, and they can also over-extract and make the coffee taste bitter. Coarse grounds look roughly like breadcrumbs or sea salt.
If you grind your own beans, use the coarse setting on a burr grinder (not a blade grinder, which produces uneven pieces). If you buy pre-ground coffee, look for bags labeled "cold brew" or "coarse grind." If your coffee shop grinds for you, ask them to grind coarse and mention that it is for cold brew — most will do this without charge.
Do not use when ready coffee or espresso grounds. when ready coffee will dissolve into the water rather than steep, and espresso grounds are too fine.
Steeping time and how to know when it is done
Cold brew steeps at room temperature for 12 to 24 hours. The longer it steeps, the stronger the concentrate becomes. At 12 hours, the coffee is mild and smooth. At 18 to 24 hours, it is noticeably stronger and more concentrated.
Start checking the taste at 12 hours. Pour a small amount of the concentrate into a cup, dilute it with water or milk, and taste it. If it is strong enough for you, strain it when ready. If you want it stronger, cover it again and check again in 6 hours. Most people find 18 hours to be the sweet spot.
Temperature matters less than you might think — cold brew will steep in a cool kitchen or a warm one, though it may steep slightly faster in warmth. You do not need to refrigerate it while it is steeping, though you can if you prefer.
Filtering and straining the grounds
After steeping, you need to separate the grounds from the liquid. The method you choose affects how clear the concentrate is and how much sediment ends up in your cup.
A fine-mesh strainer works for a first pass — pour the mixture through it into a clean jar or pitcher, letting the liquid drain while the grounds collect in the strainer. This removes most of the grounds but leaves some fine particles in the concentrate.
Cheesecloth or a coffee filter produces a clearer concentrate. Line your strainer with cheesecloth or a paper coffee filter, then pour the mixture through. This is slower — it may take 10 to 15 minutes — but the result is cleaner. If you use a French press, straightforward press the plunger down slowly to separate the grounds from the liquid.
Some people do a two-stage filter: first through a mesh strainer, then through cheesecloth or a filter. This is not necessary, but it does produce the clearest concentrate.
Diluting the concentrate and serving it
Cold brew concentrate is not meant to be drunk straight (unless you want an extremely strong cup). Dilute it before serving.
A 1:1 ratio of concentrate to water is a good starting point — for example, 2 ounces of concentrate plus 2 ounces of water. If you prefer it milder, use more water. If you like it stronger, use less water or add less ice.
You can also dilute with milk, milk alternatives, or a mix of water and milk. Some people add a splash of vanilla extract, cinnamon, or sweetener to the concentrate itself, so the flavor is built in. Others prefer to add these to the cup after diluting.
Serve it cold over ice, or heat it gently in a saucepan or microwave if you want a warm cup. Heating does not damage the flavor — cold brew reheats well.
Storage and how long the concentrate lasts
Store the strained concentrate in a sealed container in the refrigerator. It will keep for two weeks or longer, depending on how clean your equipment was and how well sealed the container is. Most people finish a batch within a week or two.
If you notice any off smell or visible mold, discard it. Otherwise, cold brew concentrate is very stable — the long steeping and the cold temperature both slow spoilage.
You can also freeze cold brew concentrate in ice cube trays, then pop out cubes as needed. This is useful if you want to make small amounts of cold brew without thawing a whole jar.
Common mistakes and how to avoid them
Using fine or medium grounds is the most common mistake. This clouds the concentrate and can make it taste over-extracted. Coarse grounds are essential.
Not tasting it before straining means you might strain it too early or too late. Check the taste at 12 hours and decide whether to strain or wait longer.
Forgetting to dilute it before drinking will make the coffee taste harsh and overly strong. Always dilute with water or milk.
Leaving it at room temperature after straining will cause it to spoil faster. Refrigerate the concentrate as soon as you finish straining.
Frequently Asked Questions
Can I make cold brew in the refrigerator instead of at room temperature?
Yes. Cold steeping takes longer — usually 24 to 48 hours — but produces the same result. Room temperature is faster, so most people use that method. If you prefer to refrigerate while steeping, plan for an extra 12 to 24 hours.
What if my cold brew tastes bitter or harsh?
Reduce the steeping time next batch, or use a coarser grind. Bitterness usually comes from over-extraction, which happens when fine grounds steep too long. You can also try a lower coffee-to-water ratio.
Can I use a coffee maker designed for cold brew instead of a jar?
Yes. Commercial cold brew makers work the same way as a jar — they steep grounds in water for 12 to 24 hours and then filter. They are convenient if you make cold brew regularly, but a jar is just as effective and costs nothing.
How much concentrate should I make at once?
Make as much as you will drink in two weeks. A quart (about one liter) is a good starting batch — it yields roughly 10 to 14 cups of diluted cold brew, depending on how strong you like it. You can scale up or down from there.
Can I use cold brew concentrate in recipes or cocktails?
Yes. Cold brew concentrate works well in coffee-flavored desserts, smoothies, and cocktails. Use it as you would use regular brewed coffee, adjusting the amount to taste.