How to Make Cold Brew Coffee at Home (Ratio, Time and Tips)

Cold brew is the most forgiving coffee you can make. You don’t need a kettle or a timer, and there’s no technique to master. You do need patience, and a few numbers matter more than you might think.

Here is how to make cold brew in one sentence: stir coarsely ground coffee into cold water (about 1 part coffee to 5 parts water by weight for a concentrate, or 1 to 12 for a ready-to-drink batch), steep it in the fridge for 12 to 18 hours, strain it twice and keep it cold. The rest of this guide explains each choice, so you can adjust the recipe to your taste and store your batch safely.

Key takeaways

• Use a coarse grind, roughly the size of rock salt, so the coffee filters cleanly.
• A 1:5 ratio by weight gives a concentrate to dilute; about 1:12 gives a batch you can pour straight over ice.
• Steep 12 to 18 hours in the fridge. In one room-temperature lab study, caffeine extraction leveled off after 6 to 7 hours; cold slows that down, which is why the fridge needs longer.
• Cold brew is never heated and is not acidic enough to protect itself, so keep it at 40°F (4°C) or below and finish it within about a week.

In this article

1. The cold brew ratio: concentrate or ready-to-drink
2. What you need
3. How to make cold brew, step by step
4. How long to steep cold brew
5. Fixing a disappointing batch
6. How long cold brew lasts and how to store it
7. Cold brew vs iced coffee
8. Serving ideas
9. The best coffee for cold brew
10. FAQ

The cold brew ratio: concentrate or ready-to-drink

The ratio is the single biggest decision. The National Coffee Association suggests 1 gram of coffee for every 4 to 5 grams of water, which gives a strong concentrate you dilute later. A weaker brew is drinkable straight from the jar but takes up more fridge space for the same number of drinks.

Weigh your coffee if you can: scoops of coarse grounds vary a lot. As a guide, 1 cup of coarse grounds weighs about 85 g (3 oz). Each recipe below uses 1 liter of water (about 4 1/4 US cups).

Why is the yield lower than the water you poured in? Wet grounds soak up part of the water (we assumed about twice the coffee’s weight for the yields above), so the stronger the ratio, the more you lose. A concentrate makes up for that, because each glass of it stretches to two once diluted.

What you need

• A large glass jar, pitcher or French press with a lid
• Coarsely ground coffee (or whole beans and a grinder with a coarse setting)
• Cold, good-tasting water: if you don’t like your tap water plain, filter it
• A fine-mesh sieve
• A paper coffee filter, a cloth filter or a nut-milk bag for the second strain
• A clean bottle or jar for storage, and a kitchen scale if you have one

How to make cold brew, step by step

1. Grind coarse. Aim for the texture of rock salt. Fine grounds make a muddy brew that clogs filters. If you buy ground coffee, choose a coarse grind made for French press or cold brew.
2. Combine. Put the grounds in the jar, pour in the cold water and stir gently for 10 to 15 seconds so no dry pockets remain.
3. Steep in the fridge. Cover the jar and refrigerate it for 12 to 18 hours. Note the start time on the lid.
4. First strain. Pour the brew through a fine-mesh sieve into a clean bowl or pitcher. Let it drain rather than pressing the grounds, which pushes fine sediment through.
5. Second strain. Pour it again through a paper filter or cloth. According to the National Coffee Association, paper catches the most oils and gives a cleaner, lighter cup. Cloth holds back more than a metal mesh but less than paper.
6. Bottle and chill. Transfer the cold brew to a clean, closed bottle, write the date on it and put it straight back in the fridge.
7. Serve. Dilute a concentrate with cold water or milk, pour it over ice and adjust to taste.

The French press shortcut

A French press is the easiest cold brew maker you probably already own. Add the grounds and water, stir and leave the plunger raised. Steep it in the fridge, then press the plunger down slowly and pour through a paper filter for a clean finish. In a standard 34 oz (1 L) press, use about 60 g (3/4 cup) of coarse coffee and 3 cups (710 ml) of water for the ready-to-drink strength.

How long to steep cold brew

Most home recipes, including the National Coffee Association’s, land around 12 hours, and many go to 18 hours or overnight. Science adds a useful detail. In a 2017 study published in Scientific Reports, researchers at Thomas Jefferson University steeped coffee at room temperature (about 70 to 77°F, or 21 to 25°C). Caffeine and 3-CGA, one of coffee’s main chlorogenic acids, reached equilibrium in 6 to 7 hours, well before the 10 to 24 hours many recipes call for.

Cold slows extraction down, which is why a fridge batch needs the longer 12 to 18 hour window. Past that point you gain little. If a batch tastes weak, the faster fix is usually more coffee, not more time.

Fixing a disappointing batch

How long cold brew lasts and how to store it

Hot coffee is brewed near boiling. Cold brew never sees that heat, and it is not very acidic either. In a 2018 study, cold brew samples measured pH 4.96 to 5.13, above the pH 4.6 threshold the FDA uses to define low-acid canned foods. Neither heat nor acidity protects it much, so the fridge does the work.

Coffee doesn’t appear on the FoodSafety.gov cold storage chart, so apply the general rules for perishable food:

• Brew it in the fridge. FoodSafety.gov notes that bacteria that cause food poisoning multiply fastest between 40°F and 140°F (4°C and 60°C). That’s why we steep in the fridge rather than leaving a jar on the counter overnight.
• Keep it at 40°F (4°C) or below. That is the official recommended fridge setting, and an inexpensive appliance thermometer lets you check it.
• Respect the 2-hour rule. Don’t leave cold brew drinks out of the fridge for more than 2 hours, or 1 hour when it is above 90°F (32°C), such as in a hot car or at a picnic.
• Use clean, closed containers. Wash jars, sieves and filters with hot soapy water before each batch and store the coffee covered.
• Finish it within about a week. We recommend drinking homemade cold brew within 7 days of brewing, and sooner for the best flavor. Throw it out if it smells sour or off, turns slimy or shows any mold.
• Add milk to the glass, not the jar. Store the coffee plain and mix in milk or sweet cream right before drinking.

Cold brew vs iced coffee

The two are often confused on menus, but they are made in opposite ways. In the National Coffee Association’s words, iced coffee is brewed hot using a standard method and then cooled down to serve. Cold brew never touches hot water.

A note on acidity: cold brew is often described as “low-acid”. The 2018 study cited above found its pH was about the same as hot coffee, but its titratable acidity (the total amount of acids present) was lower. That fits the softer taste many people notice.

A quick caffeine note

Caffeine depends on how much coffee you use and how much you dilute it. In the 2017 study, coarse-ground cold brew contained substantially more caffeine than hot coffee brewed with the same 1:10 ratio. A concentrate is strong, so don’t drink it undiluted by the glass. The FDA cites 400 mg of caffeine a day as an amount not generally associated with negative effects for most healthy adults. Caffeine is discouraged for children and teens. If you are pregnant, breastfeeding, sensitive to caffeine or take medication, ask your doctor what amount is right for you.

Serving ideas

• Classic: 1/2 cup (120 ml) concentrate, 1/2 cup (120 ml) cold water, a tall glass of ice.
• Creamy: 1/2 cup (120 ml) concentrate topped with 1/2 cup (120 ml) cold milk or oat milk.
• Vanilla sweet cream: stir 2 tbsp (30 ml) heavy cream, 1 tbsp (15 ml) milk, 1 to 2 tsp (5 to 10 ml) maple or simple syrup and a drop of vanilla. Float it on a glass of diluted cold brew.
• Hot in a hurry: mix concentrate 1:1 with just-boiled water for a smooth hot cup with no brewing.
• Coffee ice cubes: freeze diluted cold brew in a tray, so your drink gets stronger, not weaker, as the ice melts.

The best coffee for cold brew

Long, cold steeping favors coffees with chocolate and nut notes. Our Cold Brew Coffee is made for exactly this job: a dark French roast blend, coarse ground for cold brew, with dark chocolate notes and nothing added but coffee. If you prefer a single origin, Brazil Santos is a smooth medium roast with cocoa and roasted-nut notes. Order it in the Coarse grind, or as whole beans to grind just before brewing. Both are roasted 1 to 5 days before delivery. If you’re weighing whole beans against ground, our whole bean vs ground coffee guide lays out the trade-offs.

Cold brew FAQ

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

For a concentrate, use 1:4 to 1:5 by weight and dilute it before drinking. For a batch you can drink straight over ice, use about 1:12: roughly 85 g (1 cup) of coarse coffee per liter of water.

Should cold brew steep in the fridge or on the counter?

In the fridge. It takes a few more hours, but the brew stays below 40°F (4°C) the whole time instead of sitting for hours in the range where bacteria grow fastest.

How long does homemade cold brew last?

Keep it sealed in the fridge and drink it within about 7 days, ideally sooner for the best flavor. Store it plain and add milk only to the glass you are about to drink.

Can I use regular ground coffee for cold brew?

You can, but a fine or standard drip grind clogs filters and leaves sediment. A coarse grind gives a cleaner result and is much easier to strain.

Is cold brew stronger than regular coffee?

A concentrate is much stronger, which is why it is diluted. Once diluted, the strength depends on your ratio. Taste first and adjust with water, milk or ice.

Sources

1. “Cold brew coffee”, National Coffee Association. aboutcoffee.org
2. Fuller M, Rao NZ. “The Effect of Time, Roasting Temperature, and Grind Size on Caffeine and Chlorogenic Acid Concentrations in Cold Brew Coffee”, Scientific Reports, 2017. nature.com
3. Rao NZ, Fuller M. “Acidity and Antioxidant Activity of Cold Brew Coffee”, Scientific Reports, 2018. nature.com
4. “Acidified & Low-Acid Canned Foods Guidance Documents & Regulatory Information”, US Food and Drug Administration. fda.gov
5. “4 Steps to Food Safety”, FoodSafety.gov (US Department of Health and Human Services). foodsafety.gov
6. “Cold Food Storage Chart”, FoodSafety.gov. foodsafety.gov
7. “Spilling the Beans: How Much Caffeine is Too Much?”, US Food and Drug Administration, 2024. fda.gov

Facts checked in October 2026.

This article is for general information only and is not medical advice. If you have a health condition, are pregnant or take medication, ask your doctor before changing your caffeine intake.

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