How to make cold brew coffee at home

Through the long stretch from March to September in most of India, cold brew quietly becomes the most reliable way to drink good coffee at home. No 95°C water meeting a 38°C kitchen. No bitter, over-extracted brew. No machine. Just coffee and cold water, given enough time to do their work. This guide walks through how to make cold brew coffee at home — the ratio, the grind, the steep time, the storage rules, and the small fixes that take it from passable to genuinely good.

What is cold brew coffee?

Cold brew is coffee brewed slowly in cold or room-temperature water, usually for 12 to 18 hours. There is no heat at any point. The result is a smoother, lower-acid, lower-bitterness cup with a heavier natural sweetness than hot coffee made from the same beans.

The long contact time with cold water pulls a different set of compounds from the bean than hot brewing does — fewer bitter acids, more sugars and chocolate-leaning notes. That is why a cold brew tastes round and mellow even from a bean that brews bright and citric when hot. Cold press coffee, cold filter coffee, and cold brew are all names for the same method.

What you'll need

The most useful thing about cold brew is that the equipment is almost nothing. Any clean container with a lid will work as a cold brew maker:

- A 1L glass jar with a tight lid — a Mason jar, a Borosil container, even a clean pickle or pasta jar
- A dedicated cold brew maker if you want one — Hario Mizudashi, Bodum Bean, or OXO are all sold in India

You will also need a kitchen scale, a coarse grind, filtered drinking water, a fine mesh sieve and a coffee filter or muslin cloth (for straining), and a clean glass bottle for storing the finished brew. That is the entire kit. Nothing on this list is more than a few hundred rupees, and most homes already have most of it.

Cold brew coffee beans — what works

Any freshly roasted single-origin Arabica makes excellent cold brew, but a few things help.

Roast level: medium or medium-dark is the sweet spot. Light roasts can taste thin in cold brew. Very dark roasts can taste burnt and ashy.

Origin: Indian Arabica from Chikmagalur tends toward chocolate, jaggery, dried fruit, and nuts — which is exactly the flavour profile cold brew amplifies.

South American beans work too. African beans (Ethiopian, Kenyan) give floral, fruit-forward cold brews that drink more like iced tea.

Freshness: within four weeks of roast date. Cold brew is forgiving of brew error, not of stale beans. Form: whole bean, ground at home if possible. Coarse pre-ground works if you brew it within a week.

This is where most supermarket coffee falls short — the beans are not freshly roasted, so the long extraction pulls out staleness instead of sweetness.Single-origin coffees from okiru are roasted to order and shipped within 48 hours, which is what you want for this method.

Cold brew grind size

Cold brew needs a coarse grind — roughly the size of sea salt or cracked black pepper. A fine grind in a cold brew turns into sediment that no filter will fully catch, and over-extracts during the long steep, which is the most common reason a homemade cold brew comes out muddy or bitter.

If you are grinding at home, set your burr grinder to its coarsest setting and back off one notch. If you are ordering from a roaster, ask for "cold brew grind" or "coarse grind."

The cold brew ratio

The cold brew ratio is the single biggest lever in this method. Two ratios cover almost every use case.

- 1:8 concentrate — 60g coffee to 480ml water. Brew this, then dilute one part concentrate to one or two parts water or milk before drinking. Best for daily use because you can adjust strength per cup.
- 1:15 ready-to-drink — 30g coffee to 450ml water. Brew this and pour straight from the bottle over ice. Best if you want a less concentrated final drink and do not want to dilute.

Concentrate is more flexible and stores better, so it is what we recommend by default. Once you have made it two or three times, you will know which ratio you prefer.

How to cold brew — the recipe

This is the okiru house cold brew recipe, written for a jar.

1. Weigh 60g of coarse-ground coffee and tip it into a clean 1L glass jar. (1:8 concentrate ratio.)
2. Pour 480ml of cold or room-temperature filtered water over the grounds, slowly enough that every grind is wet.
3. Stir gently with a wooden or plastic spoon until no dry pockets float on top.
4. Screw the lid on tight and put the jar in the fridge.
5. Steep for 14 to 18 hours. Twelve hours is the minimum. Past 20 hours the cup starts to dull. Twelve to sixteen is the window most home brewers settle into.
6. Strain through a fine mesh sieve lined with a coffee filter, muslin cloth, or a clean cotton handkerchief. Let it drip — do not squeeze the grounds, that pushes fines and bitterness through.
7. Pour the strained brew into a clean glass bottle and refrigerate. Discard the spent grounds (they make decent compost).
8. The concentrate is ready to drink and keeps for a week in the fridge.

To serve: pour over ice in a tall glass, then add water or milk in a 1:1 or 1:2 ratio to the concentrate. Sweeten only after tasting — a good cold brew has natural sweetness that sugar covers up.

Storage and shelf life

Cold brew concentrate keeps for up to two weeks in the fridge in a sealed glass bottle. Past one week, the flavour softens and the brightness fades, so the first week is the best window. Diluted cold brew (already mixed with water or milk) should be drunk within two days. Do not freeze cold brew concentrate in bulk — the texture changes and the flavour goes flat on thawing. Coffee ice cubes (frozen concentrate poured into an ice tray) are the workaround — drop them into chilled water or milk for a drink that does not get diluted as it melts.

The right glass for cold brew

A tall 300–400ml glass is what you want — enough room for ice, concentrate, and dilution. Highball glasses, mason jars, and Borosil tumblers all work. Avoid short glasses (the ice melts faster against the warmth of your hand) and plastic (it picks up coffee oils over time). Keep two or three glasses in the freezer through summer — a chilled glass keeps the drink at temperature twice as long. The right glass for cold coffee is a small detail that quietly improves every cup.

Common mistakes that wreck a cold brew

A short list, drawn from every cold brew we have had to throw out.

Grind too fine: sediment in the cup, muddy taste, bitter finish. Coarse grind, every time. Stale beans: cold brew amplifies what the bean already is. Stale beans make stale cold brew. Steep too long: past 20 hours the brew dulls and turns flat. Twelve to eighteen is the window. Leaving brew on the grounds: strain the moment the steep ends. Storage on grounds is the single fastest way to ruin a cold brew. Tap water: chlorine, hard minerals, and chemical aftertastes all carry through into cold brew much more than into hot coffee. Use filtered water.

Get these five right and the recipe is almost foolproof.

What to brew

Medium or medium-dark single-origin Arabica from Chikmagalur is what we'd reach for first — the chocolate and jaggery notes match cold brew beautifully. Browse our current single-origin coffees and order whole bean or ground for cold brew.