The Cold Brew Ratio Nobody Told You About

The problem with most homemade cold brew is not the coffee and not the water. It's the ratio. And usually the grind. And often the steep time. So actually the problem is most people are winging three variables simultaneously and then blaming the coffee when it tastes like dirty water or motor oil.

Cold brew is simple. But simple doesn't mean there's nothing to know.

Why Cold Brew Tastes Different

Cold extraction is fundamentally different from hot extraction. Hot water is an aggressive solvent. It extracts quickly and indiscriminately, pulling out acids, aromatics, bitter compounds, and everything else at roughly the same rate. That's why hot-brewed coffee has the flavor complexity it does, and also the acidity.

Cold water is slower and more selective. Over a long steep, it extracts the sweeter, mellower, lower-acid compounds while leaving behind many of the harsher, more volatile acids that hot water pulls immediately. The result is a cup that's naturally smoother and less acidic, not because acid was added or removed, but because cold water never extracted as much of it to begin with.

This is also why cold brew has a different caffeine profile than iced coffee. Cold brew is typically made as a concentrate then diluted. A standard cold brew is often higher in caffeine than a hot-brewed cup of the same volume because the long steep extracts caffeine efficiently even in cold water.

The Ratio

For cold brew concentrate, meaning something you'll dilute before drinking, the standard ratio is 1:5 coffee to water by weight. That's 100 grams of coffee to 500 grams of water, or 200 grams to 1 liter.

If you're making ready-to-drink cold brew rather than concentrate, use 1:8 coffee to water. This is what you drink straight without diluting.

Most people eyeball this and then wonder why their cold brew is inconsistent. A kitchen scale costs less than a bag of specialty coffee. Use it.

The Grind

Coarse grind. Think sea salt texture, or the coarsest setting on most home grinders. This is important for two reasons.

First, fine grinds over-extract in cold water. The increased surface area from fine grinding combined with an 18 to 24-hour steep produces bitter, astringent cold brew that no amount of dilution fully fixes.

Second, fine grinds are a nightmare to filter. Cold brew needs to be strained after steeping, and fine grounds get through most filters and settle at the bottom of the glass. You don't want to drink that.

If you only have pre-ground coffee, standard drip grind is workable but not ideal. Reduce steep time by a few hours to avoid over-extraction.

The Steep

12 to 24 hours in the refrigerator. Not on the counter.

Counter steeping at room temperature is faster, 8 to 12 hours, but temperature inconsistency and food safety concerns make fridge steeping the better default.

18 hours is a reliable target for most beans. Light roasts sometimes benefit from the full 24 hours. Dark roasts, which are more soluble, often peak around 12 to 15 hours before over-extraction starts to show up as a heavy, muddy quality.

The Filter and the Build

Cheesecloth doubled over a fine mesh strainer works. A Chemex filter works. A nut milk bag works. Whatever you use, pour slowly and don't press or squeeze. Pressing forces fine particles through the filter and cloudiness and bitterness follow.

The finished concentrate keeps in the refrigerator for up to two weeks without significant degradation.

Concentrate over ice, diluted roughly 1:1 with water or milk. Adjust to taste. Start at 1:1 and go from there.

1775 single-origin arabica makes cold brew that's worth the 18-hour wait. The natural sweetness and clarity of an 85-plus bean are exactly what cold extraction showcases. A generic commodity blend makes cold brew that tastes like cold commodity coffee. The ratio is the same. The coffee is not.