The short answer
The best cold brew beans are medium-to-dark roasts with chocolatey, nutty, low-acid profiles — Latin American and Indonesian coffees are ideal. Cold brew's long, cold steep naturally produces a smooth, mellow cup, and darker roasts lean into that with rich body and sweetness.
Bright light roasts, which shine in pour over, often taste flat or sour when brewed cold, so they are usually the wrong pick here.
Why medium-to-dark roasts win cold
Cold water extracts fewer acids and aromatics than hot water, so the bright, delicate notes of a light roast largely disappear — leaving a thin, sometimes sour cup. Medium-to-dark roasts bring chocolate, caramel, and nutty flavors that survive the cold steep and give cold brew its signature smooth, full body.
Look for tasting notes like chocolate, brown sugar, nuts, and "low acid." A dark-roast blend built for cold brew is a safe, repeatable choice.
Grind coarse and get the ratio right
Cold brew needs a coarse grind — like coarse sea salt — so the long steep does not turn bitter or muddy. Use plenty of coffee: a 1:5 concentrate you dilute, or 1:8 ready-to-drink. Steep 12 to 24 hours, then filter.
The cold brew calculator does the coffee-and-water math for any batch size, and how to make cold brew at home walks the full method.