Quick answer: Mix coarse-ground coffee with cold, filtered water at 1:5 by weight for a concentrate (or 1:8 to drink straight). Steep 12–16 hours in the fridge, or 8–12 hours at room temperature, then strain through a paper filter. Dilute the concentrate 1:1 with water or milk and keep it refrigerated for up to about a week.
Cold brew is one of the easiest brews to make at home, and it is also surrounded by bad advice: 24-hour steeps, special “cold brew blends”, espresso-fine grinds. This guide gives you a recipe that works, explains what the research actually says about steep time, and shows the few shortcuts that really speed things up.
Cold Brew Ratio and Steep Time Cheat Sheet
| Style | Coffee : water (by weight) | Example batch | Steep | How to serve |
|---|---|---|---|---|
| Concentrate | 1:5 | 100 g coffee + 500 g water | 12–16 h fridge | Dilute 1:1 with water or milk |
| Ready to drink | 1:8 | 100 g coffee + 800 g water | 14–18 h fridge | Straight over ice |
| Room-temperature batch | 1:5 to 1:8 | Same as above | 8–12 h counter | Strain, then refrigerate |
| Japanese iced (flash brew) | 1:15 total, with about 40% of it as ice | 30 g coffee, 270 g hot water, 180 g ice | 3–4 min | Brew hot directly onto ice |
Want different amounts? Use our brew ratio calculator to scale any batch.
How to Make Cold Brew at Home (Step by Step)
- Weigh and grind. Use 100 g of beans, ground coarse, like rough sea salt or a French press setting. A burr grinder gives you even particles, which makes it easier to strain and gives a cleaner taste.
- Add water. Pour in 500 g of cold, filtered water for a concentrate. Stir for 15–20 seconds so every ground is wet.
- Steep. Cover and refrigerate for 12–16 hours. Taste at 12 hours: if it is thin, give it more time; if it is woody or harsh, cut the time next batch.
- Strain twice. Pour through a fine mesh sieve first, then through a paper filter (a pour-over cone works well). The paper catches the fine silt that turns cold brew muddy.
- Dilute and serve. Mix the concentrate 1:1 with water or milk over ice. Store it in a sealed jar in the fridge.
What the Research Says About Steep Time
A 2017 study by chemists at Thomas Jefferson University measured caffeine and chlorogenic acid in cold brew over time. Both reached equilibrium between 6 and 7 hours at room temperature, much sooner than the 10–24 hours most recipes call for. Grind size did not significantly change those concentrations (Fuller & Rao, Scientific Reports, 2017).
What that means for you: at room temperature, the main extraction is finished well before a full day, so 24-hour steeps mostly add time, not flavour. A cold fridge slows extraction down, which is why 12–16 hours is a sensible fridge window. Flavour is more than caffeine and acids, so taste your own coffee and adjust.
3 Cold Brew Myths That Waste Time and Money
Myth 1: It must steep for 24 hours
It doesn’t. As the research above shows, key compounds stop increasing after about 6–7 hours at room temperature. Very long steeps often taste woody or flat. Start at 12 hours in the fridge and only go longer if your cup tastes weak.
Myth 2: You need a special “cold brew blend”
Any fresh coffee you enjoy will work. Medium and medium-dark roasts give the classic chocolatey, nutty cold brew. Light roasts make a brighter, fruitier cup, which some people love. The Jefferson study found higher caffeine and chlorogenic acid in cold brew made from medium roasts than from dark roasts. Choose by taste, not by the label.
Myth 3: A finer grind extracts better
For an easy home brew, it mostly makes straining harder. Fine grounds clog filters and leave a silty, bitter cup. Since grind size barely changed caffeine and acid levels in the study, a coarse grind gives you the same strength with far less mess.
Is Cold Brew Less Acidic?
Partly. A 2018 follow-up study found that cold and hot brew made at the same ratio had similar pH (about 4.85 to 5.13), but hot brew had higher titratable acidity. In other words, cold brew is not much different on the pH scale, but it has fewer total acids, which is why it often tastes smoother and less sharp (Rao & Fuller, Scientific Reports, 2018).
5 Hacks That Actually Speed Up Cold Brew
- Steep on the counter, then chill. Room temperature extracts faster than the fridge. Steep 8–12 hours on the counter, strain, then refrigerate.
- Stir early. A good stir at the start, and once more after an hour, makes sure no dry clumps are left. Dry pockets are the most common cause of weak batches.
- Brew a stronger concentrate. A 1:4 to 1:5 ratio tastes full even at the short end of the steep window, and you can always dilute more.
- Use flash brew when you need it now. Japanese iced coffee (hot coffee brewed straight onto ice) is ready in minutes. It is brighter than cold brew, but chilled and refreshing.
- Make big batches. The concentrate keeps well, so one weekend batch covers most of the week. That is the biggest time-saver of all.
Skip the gimmicks you may see online, like freezing the slurry or grinding finer than espresso. They add mess without a clear benefit.
Equipment: What You Really Need
- Minimum: a large jar, a fine mesh sieve and paper filters. A French press works too: steep in it, then plunge and filter.
- Nice to have: a dedicated cold brew maker such as a Toddy, OXO or Hario bottle. These make straining simpler, but they don’t make better coffee than a jar.
- Worth it: a kitchen scale and a burr grinder. They make every batch repeatable.
Troubleshooting Your Cold Brew
| Problem | Likely cause | Fix |
|---|---|---|
| Weak or watery | Too little coffee, or too short a steep | Move toward 1:5, add 2–4 hours |
| Bitter, woody | Steeped too long | Cut the steep by 2–4 hours |
| Muddy or silty | Grind too fine, or no paper filter | Grind coarser and strain through paper |
| Flat, stale taste | Old beans, or stored too long | Use fresher beans; drink within a week |
| Sour | Under-extracted, or the roast is very light | Steep longer or try a medium roast |
Frequently Asked Questions
What is the best ratio for cold brew?
For a concentrate, 1:5 coffee to water by weight, diluted 1:1 when you serve it. To drink it straight over ice, use 1:8.
How long should cold brew steep?
12–16 hours in the fridge, or 8–12 hours at room temperature. Research shows caffeine and chlorogenic acid level off after about 6–7 hours at room temperature, so there is no need to wait 24 hours.
How long does cold brew last in the fridge?
Most people find it tastes best within about a week. Concentrate generally keeps a little longer than diluted cold brew. Store it sealed and cold, and throw it out if it smells off.
What grind size is best for cold brew?
Coarse, like rough sea salt. It strains cleanly and gives a smooth cup.
Is cold brew the same as iced coffee?
No. Cold brew is never heated, while iced coffee is brewed hot and then chilled. See our full cold brew vs iced coffee comparison.
Keep Learning
- Cold brew vs iced coffee: what’s the difference?
- Home nitro coffee setup: turn cold brew into nitro
- Water chemistry for better extraction
- Brew ratio calculator
Sources
- Fuller, M. & Rao, N. Z. (2017). The Effect of Time, Roasting Temperature, and Grind Size on Caffeine and Chlorogenic Acid Concentrations in Cold Brew Coffee. Scientific Reports 7, 17979.
- Rao, N. Z. & Fuller, M. (2018). Acidity and Antioxidant Activity of Cold Brew Coffee. Scientific Reports 8, 16030.
- National Coffee Association. Cold brew coffee.
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