Cold brew is one of those things that sounds complicated until you do it once. The process is genuinely simple: coarse-ground coffee, cold water, time in the fridge. The variables that actually matter are the coffee-to-water ratio, the steep time, and the roast you start with. Get those three right and the rest takes care of itself.

The ratio: why 1:12 is a good starting point

Most cold brew guides suggest somewhere between 1:8 and 1:15 (coffee to water by weight). The lower end gives you a concentrate you dilute before drinking; the higher end gives you something ready to drink straight. We've found 1:12 to be the most useful starting point for a ready-to-drink cold brew. It's strong enough to hold up over ice as it melts but not so concentrated that it tastes harsh. If you're making concentrate to mix with milk or water, drop to 1:8 and dilute 1:1 before serving.

Steep time: 14 hours in the fridge, not on the counter

Steep in the fridge, not at room temperature. Room-temperature cold brew extracts faster but also extracts more of the bitter compounds you're trying to avoid. In the fridge at around 4°C, 12-16 hours is the right window. We've settled on 14 hours as the standard after running 18 test batches this summer. Under 12 hours and the cup is thin; over 16 hours and you start to get a slightly astringent finish, particularly with natural-process coffees.

Which roast works best cold?

Natural-process coffees tend to perform better as cold brew than washed lots. The fruit-forward flavours that come from natural processing. Blueberry, stone fruit, dark berry. Become more pronounced in cold extraction, not less. Our Kochere Natural is the one we'd point you to first. The Finca La Hermosa Guatemala (honey process) is a close second, with a clean cocoa note that holds up well even when diluted with ice melt. The Kochere Washed is lovely as a hot V60 but flattens out a bit in cold extraction.

Grind size and filtering

Use a coarse grind. Roughly the texture of coarse sea salt. Too fine and you'll over-extract and struggle to filter it cleanly. Filter through a paper filter (a V60 filter works well) or a fine-mesh sieve lined with a paper towel. The paper filter gives a cleaner cup; the mesh gives a slightly fuller body. Both work. Store the finished cold brew in the fridge and drink within 10 days, though in practice it rarely lasts that long.

Cold brew is a good use of a bag that's slightly past its peak for hot brewing. Say, 3-4 weeks off roast. The cold extraction is forgiving enough that the slight staleness doesn't show up in the cup the way it would in a V60.