Coffee Calculators
Iced Coffee Flash Brew Calculator
https://www.coffeesizing.com/calculators/iced-coffee-flash-brew/
Estimate only — not a cupping score, a water lab or a roast profile. Confirm on a test brew.
Iced Coffee Flash Brew Calculator
Flash brew is hot coffee poured onto ice so you do not wait for a carafe to chill. The ice is part of the recipe water, not a garnish. If you brew a full 1:16 hot and then dump ice in, you drown the cup. Weigh ice, subtract it from the total, pour the rest hot — and still bloom on the dry bed.
Inputs
Results
- Hot brew water
- 180.0g
- Hot brew ratio
- 9.00
- Ice share
- 40.0%
Coffee to hot water only. Final drink ratio is dose to total beverage.
Recommended gear
Hario V60 dripper
Flash brew is a V60 (or similar) into a server of ice. Keep the bed hot; the ice lives downstairs.
Typical range: $10–$40
Fellow Stagg kettle
A hold-temp gooseneck keeps 92–96 °C while you bloom, so the ice is the only cooling step.
Typical range: $150–$200
0.1 g coffee scale
Weigh ice and brew water separately. Volume of cubes is a terrible proxy for grams of water.
Typical range: $20–$80
Calculation method
Hot brew water is total beverage minus ice. The hot brew ratio is that water divided by dose — it will look tighter than a hot 1:16 because the ice finishes the recipe. Ice percent is ice over total mass. If ice is 120 g of a 300 g drink and dose is 20 g, you brew 180 g hot (1:9) and melt to 1:15 overall.
Exact formula
brewWaterG = totalBeverageG − iceG. brewRatio = brewWaterG / coffeeDoseG. icePercent = 100 × iceG / totalBeverageG. Bloom uses brew water, not ice. Limits: Incomplete melt, dilution from leftover ice and server heat omitted.
Clear ice, clearer math
Wet ice from the tray is already water. Tare a dry server, add ice, read grams. Do not count the puddle twice.
Grind a notch finer
You are pushing a smaller mass of hot water through the same dose, so contact time can run short. A slightly finer grind size than your hot V60 often saves the cup.
Frequently asked questions
Why brew stronger than my usual V60?
Because the ice is recipe water. If you brew 1:16 hot onto ice, the glass becomes 1:20-something after melt. That is iced dishwater, not flash brew.
Still bloom?
Yes, with hot water on the grounds. Ice in the server does not wet the bed. Use 2–3× dose from the hot water, not from the ice.
Japanese iced coffee vs cold brew?
This is hot extraction onto ice. Cold brew is a long steep. Different sweetness, different caffeine extraction, different clock.
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