Use roughly 40–60% of your total water as ice. A common starting point is a 1:16 total ratio with half the water brewed hot over the grounds and the other half as ice in the server. The calculator splits it for any batch size.
What is the best ratio for iced coffee?
Most flash-brew recipes land between 1:15 and 1:17 total water to coffee, counting both hot water and ice. That is the same strength you would brew hot, because the ice replaces the water you would otherwise add and prevents dilution.
What is flash brew coffee?
Flash brew (also called Japanese iced coffee) means brewing hot coffee directly onto ice. The ice chills it instantly, locking in aromatics and acidity that slow cold brew does not capture, in minutes instead of 12+ hours.
Why use less hot water when brewing iced coffee?
The ice is part of your recipe. If you brewed a full-strength hot cup and then poured it over ice, it would melt the ice and taste watery. Brewing a more concentrated hot portion over ice lands at normal strength once it cools.
Which coffees are best for flash brew?
Bright, fruity light roasts such as washed Ethiopians and Kenyans hold up well because chilling keeps their acidity and floral aromatics. See our best coffee for flash brew picks.
How is this different from cold brew?
Flash brew uses hot water for a few minutes and is ready immediately, with a brighter, more acidic cup. Cold brew steeps for 12–24 hours and is smoother and lower in acidity. Try the cold brew calculator for that method.
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