Cold Brew Concentrate Recipe: Ratios, Steep Time, and Serving Ideas

Cold brew rewards preparation and punishes nothing much. That is the appeal. You mix coffee and water, walk away, and strain it the next day. The result is a concentrate that keeps for days and gives you an iced coffee in about the time it takes to fill a glass. The details that matter are few, but they matter a lot: how much coffee you use, how coarsely you grind it, and how long you leave it alone. Get those three right and everything else is a matter of taste.

This is the recipe I come back to, along with the adjustments that make it work in a small kitchen with ordinary equipment.

Start With the Ratio

A concentrate needs enough coffee to survive dilution. Too weak and you end up pouring a watery drink that tastes of very little; too strong and the flavours tip into harsh, woody territory. The reliable starting point is 1 part coffee to 4 parts water by weight. In practical terms: 100 g of ground coffee to 400 g (400 ml) of water. That fills a one-litre jar about halfway and yields roughly 350 ml of concentrate after the grounds absorb their share.

Weighing is worth the small effort. Coffee beans vary in density, so a scoop of dark roast and a scoop of light roast are not the same amount of coffee. A cheap digital scale removes the guesswork permanently.

• 1:4 by weight — a true concentrate, ideal for milk drinks and for anyone who likes a firm, syrupy iced coffee.
• 1:5 by weight — a slightly softer concentrate, easier to drink with only a splash of water.
• 1:8 — ready to drink as is, no dilution needed. Good if you want to skip the maths entirely.
• 1:12 to 1:15 — the lighter end, closer to a standard filter coffee served cold. Fine, but this is not really a concentrate.

Scale up in the same proportions. A 500 g bag of coffee and 2 litres of water gives you a batch that will carry most households through a week.

Grind Coarser Than You Think

Cold brew needs a coarse grind, similar to coarse sea salt or the texture of raw sugar. It should feel gritty between your fingers, not powdery. There are two reasons. Fine particles clog your filter and leave a muddy, silty drink. And long contact with water pulls out the harsh compounds that a shorter hot brew would leave behind.

If your grinder has numbered settings, start around the coarsest third of the range and adjust from there. Blade grinders are difficult for this; pulse in short bursts and accept a little inconsistency. If the finished concentrate drains painfully slowly through a paper filter, the grind was too fine.

Use cold or room-temperature filtered water. Chlorine and heavy mineral content both flatten the flavour, and since you are not boiling anything, there is no opportunity to drive those off. Tap water that tastes good on its own is usually fine.

Steep Time and Temperature

Twelve to eighteen hours is the usable window. Within it, you are tuning strength and smoothness rather than chasing a magic number.

Room temperature

Leave the jar on the counter for 14 to 16 hours. Extraction is quicker and the result has a rounder, slightly sweeter body. This is the version most coffee bars serve.

In the fridge

Steep for 18 to 20 hours. The colder water slows extraction, so you need more time for the same strength, but the flavour is cleaner and more defined. It is also more forgiving: an extra two hours in the fridge harms very little, while an extra two hours on a warm kitchen counter can tip a batch toward bitterness.

Stir once when you combine the coffee and water, making sure all the grounds are saturated. Then leave it. Repeated stirring just agitates the bed and pushes fine particles into suspension.

Straining Without the Sludge

Strain in two stages. First pour the slurry through a fine-mesh sieve or a nut milk bag to catch the bulk of the grounds. Then filter the liquid through a paper filter — a pour-over cone works well — or through a clean cloth. The second pass is slower and slightly annoying, and it is the difference between a concentrate that sits clear in the glass and one that clouds as soon as you pour it.

Do not press or squeeze the grounds hard to extract the last drops. That final push releases fine sediment and bitter compounds. Let gravity do the work and accept the small loss.

How to Dilute It

Dilution is where most cold brew goes wrong, usually because it is done by eye and the ice melts. Start with these proportions, taste, and adjust.

1. 1 part concentrate to 1 part water over plenty of ice — a strong, bracing iced coffee.
2. 1 part concentrate to 2 parts water — closer to a normal cup of coffee, served cold.
3. 1 part concentrate to 1 part milk — a cold brew latte with real backbone.
4. 1 part concentrate to 2 parts tonic or sparkling water — bright, dry, and surprisingly good with a strip of orange peel.

Because ice dilutes as it melts, mix slightly stronger than your target and let the glass finish the job. If you want the drink to hold its strength to the last sip, freeze some concentrate into ice cubes and use those instead of water ice.

Serving Ideas Worth Repeating

Black, over ice, is the benchmark and a good place to stay. But a batch of concentrate is a base, and it takes well to a few simple additions.

• Cold brew with cold foam — whip a little milk until it thickens, then spoon it over the top. No syrup required.
• Maple oat latte — concentrate, oat milk, and a teaspoon of maple syrup, shaken rather than stirred.
• Sweetened condensed milk — a spoonful in the bottom of the glass, poured over with concentrate and plenty of ice. Stir before drinking.
• Over vanilla ice cream — a small pour turns dessert into something worth sitting down for.
• Hot, if you like — dilute with hot water rather than cold. It will not taste like a pour-over, but it is smooth and low in acidity.
• A pinch of salt — in the glass, not the batch. It mutes bitterness without making the drink taste salty.

Storing the Batch

Keep the concentrate in a sealed glass bottle in the fridge. It holds for about a week, though the flavour is at its best in the first three or four days; after that it flattens gradually and picks up whatever else is in the fridge. Label it if you share a kitchen, because very dark liquid in an unmarked bottle invites questions.

Freeze what you will not finish in an ice cube tray. Those cubes are useful for future glasses and for cooling a batch without diluting it.

Fixing a Batch That Went Wrong

If the concentrate tastes bitter and drying, the grind was probably too fine or the steep ran long — dilute it a little further and shorten the next batch by two hours. If it tastes thin or vegetal, the coffee was under-extracted: grind slightly finer, add an hour, or tighten the ratio to 1:4. Muddy texture almost always means fine particles, so check your grinder setting and use a paper filter for the second strain. And if the flavour simply falls flat, look at the water before you blame the beans.

Your First Batch, This Weekend

Weigh 100 g of coarsely ground coffee into a one-litre jar, add 400 g of cold filtered water, stir once, and cover. Leave it on the counter for 15 hours, or in the fridge for 19. Strain twice, bottle it, and taste a small pour diluted 1:1 with water. Adjust the next batch in one direction only — a finer grind, a longer steep, or a tighter ratio — so you know what changed. Two or three rounds and you will have a house recipe you no longer need to think about.

Photo: Kai-Chieh Chan / Pexels