Cold Brew Coffee: Ratio, Steep Time & Method

Cold brew is the most forgiving coffee you can make at home. There is no hot water, no rushing and no delicate timing. You simply steep coarsely ground coffee in cold water, wait, and strain. The result is a smooth, low-acidity concentrate that keeps in the fridge for over a week and tastes brilliant over ice or topped with milk. If you have ever found iced coffee bitter or watery, cold brew is the fix.

The cold brew ratio

The whole method hinges on getting your coffee-to-water ratio right. For a concentrate you dilute later, use 1:8, which is one part coffee to eight parts water by weight. For a ready-to-drink batch you can sip straight away, go closer to 1:15.

• Concentrate (1:8): 125g coffee to 1L water, then dilute 1:1 with water or milk when serving.
• Ready to drink (1:15): 65g coffee to 1L water, no dilution needed.

Weighing your coffee and water is the single biggest thing you can do to make your brew consistent. If you would rather dial in the exact amounts for your jug or bottle, our cold brew ratio calculator does the maths for you.

Grind size matters

Cold brew wants a coarse grind, roughly the texture of raw sugar or coarse sea salt. Because the coffee sits in water for so long, a fine grind will over-extract and turn muddy and bitter, and it also makes filtering a nightmare. Coarse grounds extract slowly and evenly, which is exactly what you want over a long steep.

Steep time

Steep your cold brew for 12 to 18 hours. Around the 14 to 16 hour mark tends to be the sweet spot for most beans. You can steep at room temperature or in the fridge. Room temperature extracts a touch faster and pulls out more sweetness, while the fridge is gentler and gives a cleaner cup. If you go past 24 hours the brew can start to taste woody, so it is worth straining on time.

Step by step

• Weigh your coffee and grind it coarse.
• Combine the grounds and cold, filtered water in a jar or jug and stir gently so everything is saturated.
• Cover and leave to steep for 12 to 18 hours.
• Strain through a fine mesh sieve lined with a paper filter, or a dedicated cold brew filter, into a clean bottle.
• If you made concentrate, dilute to taste. Serve over plenty of ice.

Store the strained brew in a sealed bottle in the fridge and it will stay fresh for up to two weeks, though it rarely lasts that long.

Choosing your beans

Cold brew suits medium to dark roasts beautifully, drawing out chocolate, caramel and nutty notes without any harshness. Lighter roasts work too and lean fruity and bright. Whatever you choose, fresh beans make a real difference, so buy whole beans and grind just before brewing.

The home brewing payoff

One of the quiet joys of cold brew is how far a batch stretches. A single 1L concentrate can yield a week of iced coffees, which makes it far cheaper than a daily takeaway cup. If you are curious just how much you could save by brewing at home instead of buying out, our coffee savings calculator puts a real number on it. For many people, the machine or grinder pays for itself faster than they expect.

Get brewing

Cold brew rewards patience over precision, but a good ratio still sets you up for the best result. Lock in your amounts with the cold brew ratio calculator, then see what a summer of home-brewed iced coffee could save you with the coffee savings calculator. Grab some fresh beans, fill a jug tonight and wake up to smooth cold brew tomorrow.