For flash brewed iced coffee, use about 30 g of coffee for 500 g of total water, split into roughly 335 g of hot water and 165 g of ice in the carafe. That's Counter Culture Coffee's recipe, and it puts the iced coffee ratio near 1:16.7 overall, with about a third of the water arriving as ice.
| Recipe | Coffee | Hot water | Ice | Overall ratio |
|---|---|---|---|---|
| Counter Culture Coffee | 30 g | 335 g | 165 g | about 1:16.7 |
| Nossa Familia Coffee | 34 g | 270 ml | 270 g | about 1:15.9 |
| Devoción | 40 g | 300 ml | 200 g | about 1:12.5 |
How flash brewing works
Flash brewing, often called Japanese style iced coffee, means brewing hot coffee straight onto ice. You start with less hot water than usual, so the coffee comes out strong. The ice in the carafe then melts as the coffee lands on it, chilling it right away and bringing it back to normal strength.
The key idea is that ice counts as part of your water. If you brewed a normal hot cup and poured it over ice, it would melt the ice and end up watery. Flash brewing plans for that melt from the start.
Choosing your iced coffee ratio
Look at the hot water alone and these recipes are strong: about 1:11 for Counter Culture, about 1:8 for Nossa and 1:7.5 for Devoción. Add the ice and they land between roughly 1:12.5 and 1:17 overall. The ice share also varies, from about a third of the total water (Counter Culture) to half (Nossa).
- Balanced and bright: Counter Culture's 30 g, 335 g hot, 165 g ice.
- A little fuller: Nossa's 34 g with equal parts hot water and ice.
- Bold, for milk: Devoción's 40 g with 300 ml hot water and 200 g ice.
Start with one, keep the ratio steady for a few days, and adjust the coffee dose first if you want it stronger or lighter.
How to flash brew step by step
- Put the ice in your carafe or server first and weigh it.
- Grind your coffee a little finer than you would for hot pour over. Counter Culture compares it to table salt, and Devoción suggests one notch finer than your pour over setting.
- Set your dripper on the carafe, add the grounds and zero the scale.
- Heat the water. Counter Culture uses 200°F and Devoción uses 205°F.
- Pour a little water to wet the grounds, wait, then pour the rest slowly until you reach your hot water target.
- Swirl the carafe so the ice melts evenly, then pour over fresh ice in the glass.
Nossa Familia suggests aiming for about 4 minutes of total brew time, and grinding finer to get there if your usual recipe runs shorter.
Common mistakes
- Forgetting to weigh the ice. The ice is part of the recipe. Guessing it changes the final strength.
- Using your usual hot recipe. Full water plus ice means a weak, watery glass.
- Keeping your usual grind. All three recipes call for a fairly fine grind, about like table salt or a notch finer than pour over.
- Letting the hot coffee sit before it hits the ice. The whole point is to chill it as it brews.
For more on dosing coffee consistently, see our guide to measuring coffee grounds.
A practical tip: weigh your coffee dose separately before you start, so the scale under your carafe is free for ice and water. The MeasureMate digital measuring spoon scoops and weighs beans in one step, reads in 0.1 g steps and has a tare button to zero the reading between scoops.
Quick questions
Can I just pour hot coffee over ice?
You can, but it will taste diluted unless you brewed it stronger. Flash brewing uses less hot water so the melted ice brings it back to normal strength.
Is flash brew the same as cold brew?
No. Flash brew is brewed hot and chilled instantly over ice. Cold brew steeps in cold water for hours and tastes different.
How much coffee for one big glass of iced coffee?
Counter Culture's recipe makes one 16 oz iced coffee with 30 g of coffee, 335 g of hot water and 165 g of ice.
Ratios based on Counter Culture Coffee, Nossa Familia Coffee and Devoción's brew guides.