How to Make Cold Brew Concentrate: 1:4 Ratio, 12-Hour Steep

To make cold brew concentrate, stir 200 g of coarse-ground coffee into 800 ml of cold filtered water, steep it in the fridge for about 12 hours, then strain it. Serve it diluted, starting at about 1 part concentrate to 2 parts water or milk, and keep the sealed jar in the fridge for no more than seven days. The concentrate is coffee steeped at roughly one part coffee to four or five parts water, so a single batch can cover several days of iced coffee. The National Coffee Association puts the ratio at 1:4 to 1:5 by weight and the steep at around 12 hours, though it notes that times vary widely (NCA cold brew guide).

This guide covers the batch, the steep, straining, storage limits and how much to dilute. Daily Home Coffee does not test products; every figure below comes from a named source or is a recipe starting point.

What You’ll Need to Make Cold Brew Concentrate

Cold brew needs no special machine: a jar, a filter and a fridge are enough. What matters is the ratio, the grind and the time.

Ingredients

Coarsely ground coffee: 200 g
Cold, filtered water: 800 ml

That is 1 part coffee to 4 parts water by weight, at the strong end of the range the NCA gives for concentrate. Weigh the coffee if you can. Volume scoops of coarse grounds vary enough between roasts that the ratio drifts.

Gear

A jar or pitcher of at least 1.5 litres, since the grounds take up room as well as the water
A fine-mesh sieve, plus cheesecloth or a paper filter
A second jar for the strained concentrate
A grinder, if you are starting from whole beans
A scale, ideally

Step-by-Step: How to Make Cold Brew Concentrate at Home

Step 1: Grind Coarsely

Grind to about the texture of coarse sea salt. Too fine and the long steep pulls out bitterness and grit that clogs the filter; too coarse and the water never gets at the middle of the particles, so the concentrate tastes thin.

If you have no grinder, pre-ground coffee sold for a French press is the closest match. Espresso grind is far too fine for this method.

Step 2: Combine Coffee and Water

Put the 200 g of coarse grounds in the jar, add 800 ml of cold filtered water, and stir gently until every pocket of dry grounds is wet. Grounds that stay dry on top never extract.

Step 3: Steep for About 12 Hours

Cover the jar and refrigerate. The NCA gives an approximate 12 hours of contact between coffee and water as its quick-number, while noting that steeping times “can vary significantly, from as little as a few minutes to 12–18+ hours overnight”. The storage limit below assumes the batch was steeped and kept in the fridge; if you steep at room temperature, that guidance does not cover it, so brew in the fridge if you plan to keep the batch all week.

A practical schedule: start it in the evening, strain it the next morning. That lands near 12 hours without you timing anything.

Shorter steeps taste thinner and longer ones extract more, and past a point the extra extraction tastes bitter, not stronger. Twelve hours is a sane default: it is the NCA’s quick-number for cold brew, and it fits an overnight schedule.

Step 4: Strain the Concentrate

Set a fine-mesh sieve lined with cheesecloth or a paper filter over the second jar and pour the mixture through slowly. A second pass through a paper filter removes the fine sediment that makes cold brew feel gritty.

Do not press or squeeze the grounds to get more liquid out; that pushes fine particles and harsh compounds into the batch.

Step 5: Store It as Concentrate

Keep the strained concentrate in a sealed container in the fridge and dilute only the portion you are about to drink. The grounds hold on to a fair share of the water, so 800 ml going in gives you noticeably less than 800 ml of concentrate out.

How Long Cold Brew Concentrate Keeps

Treat seven days as the ceiling. Wisconsin’s agriculture department classifies cold brew made without a heat step as a time/temperature control for safety (TCS) food and advises holding it at 41 °F (5 °C) or below and date-marking it for no more than seven days from production (Wisconsin DATCP cold brew fact sheet). That guidance is written for food service, but the reason applies at home: the liquid is never pasteurised.

Two practical consequences:

Store it cold and sealed. Keep the container in the body of the fridge, not in the door, where the temperature swings.
Do not dilute the whole batch. Dilute only what you are about to drink, so the rest stays as concentrate and you can adjust each glass.

Flavour also declines before the safety limit: it generally fades over the storage period, so the concentrate tastes best in the first few days.

Wisconsin DATCP’s botulism concern applies to cold brew that is kegged or held in reduced-oxygen packaging (such as nitrogen-flushed containers) and then mishandled; an ordinary lidded jar in the fridge is not that kind of packaging.

How to Dilute and Serve It

Concentrate is not meant to be drunk neat. Start at 1 part concentrate to 2 parts water or milk, then adjust.

Iced coffee: 1 part concentrate, 2 parts water, plenty of ice
Stronger cup: 1 part concentrate, 1 part water
Long, light drink: 1 part concentrate, 3 parts water
With milk: 1 part concentrate, 2 parts cold milk for a cold latte

Ice counts as dilution, so a glass packed with ice needs a stronger mix than one you chill without ice.

Other ways to use a batch

Hot coffee: top the concentrate with hot water. You get a smoother cup that does not taste like drip coffee.
Coffee ice cubes: freeze concentrate and use the cubes in iced coffee so the drink does not water down.
Affogato: pour a little concentrate over vanilla ice cream.
Milk drinks: oat milk and cold brew work well together because the concentrate is strong enough to carry the dilution.

What Cold Brew Actually Tastes Like, and Why

Cold brew is usually described as smoother and less bitter than hot coffee, and the NCA attributes that to brewing without heat over a longer time. The acidity story is more specific than the usual “low acid” claim.

In a peer-reviewed comparison of cold and hot brews made from the same light-roast coffees at the same grind-to-coffee ratio, the pH of the two was comparable, ranging from 4.85 to 5.13, while the hot brews had higher total titratable acidity and higher antioxidant activity (Rao & Fuller, Scientific Reports). In plain terms: in that study, cold brew was not meaningfully less acidic in pH, but it had lower total titratable acidity. That is not the same as being gentler on any particular stomach, and nothing here is medical advice.

Choosing Beans for Cold Brew

Medium to dark roasts: the conventional choice, giving chocolate and nutty notes that survive a long cold steep. The roast level guide explains how the levels differ.
Light roasts: work, but their fruit and floral notes are muted by cold water, and under-extraction reads as sharp rather than bright.
Freshness: beans a few days to a few weeks past roast are a common choice.

Common Mistakes to Avoid

Grinding too fine. The most common cause of bitter, muddy concentrate and a filter that clogs.
Under-steeping. Well under 12 hours usually gives a thin, sour result.
Using heavily chlorinated tap water. Filtered water gives a cleaner cup; very soft or distilled water can taste flat.
Skipping the second strain. If the concentrate feels gritty, pass it through a paper filter.
Keeping it too long. Seven days is the limit, and flavour is best in the first few.
Diluting the whole batch at once. It ages faster and you lose the flexibility of adjusting each glass.

Frequently Asked Questions

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

The NCA gives 1:4 to 1:5 by weight. A 200 g batch in 800 ml of water is 1:4, which is strong enough to dilute 1:1 or 1:2 when serving.

How long does cold brew concentrate last in the fridge?

Up to seven days, held at 41 °F (5 °C) or below in a sealed container, following food-service guidance for cold brew made without a heat step. Flavour peaks well before that.

Can I use pre-ground coffee?

Yes, if it is coarse. Coffee ground for a French press works; espresso grind does not, because it clogs the filter and over-extracts.

Is cold brew stronger than regular coffee?

The concentrate is, because it is brewed at a much higher coffee-to-water ratio. How much caffeine ends up in your glass depends on the beans, the steep and how far you dilute it; a 1:1 pour is noticeably stronger than a 1:3 pour.

Can I heat cold brew concentrate?

Yes. Add hot water to a portion of concentrate. It tastes smoother than drip coffee rather than identical to it, and it lacks some of the aromatics of a hot-brewed cup, so it is not a substitute for one.

Why does my cold brew taste bitter?

Usually over-extraction: too fine a grind, a steep well beyond the 12-hour reference, or squeezing the grounds while straining. Go coarser and stop pressing the filter. The grind size troubleshooting guide covers the same logic for hot brews.

Making the Batch Work for Your Week

Weigh 200 g of coarse grounds, add 800 ml of cold filtered water, refrigerate for about 12 hours, then strain twice into a sealed jar. Dilute by the glass, keep the jar cold, and finish it within a week.

From there the variables worth changing are the ones that carry taste: the coffee you choose, the grind, and the steep length. Change one at a time so you can tell which one made the difference.