Coffee Drink
Japanese Iced Coffee: A Precise Flash Brew Recipe
Brew Japanese iced coffee with a measured 1:15 recipe: 20 g coffee, 180 g hot water and 120 g recipe ice. Learn the pour schedule and fix weak or sour cups.
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What Is Japanese Iced Coffee?
Japanese iced coffee is hot pour-over coffee brewed directly onto a measured amount of ice. This recipe uses 20 g coffee and 300 g total recipe water: 180 g hot brew water plus 120 g ice. The ice is part of the 1:15 brewing ratio, not an unmeasured garnish.
Key Takeaways
- 1Count hot water and recipe ice together: 20 g coffee to 300 g total water is a 1:15 ratio.
- 2Use 180 g hot water for extraction and 120 g ice for rapid chilling.
- 3Rinse the filter with separate water so the rinse does not dilute the recipe.
- 4Treat drawdown time as diagnostic evidence, then adjust grind by taste.
Flash Brew at a Glance
- Coffee
- 20 g
- Hot water
- 180 g
- Recipe ice
- 120 g
- Total ratio
- 1:15
- Water
- 94 C
- Brew time
- About 3 minutes
Japanese Iced Coffee Ratio
This table scrolls horizontally on smaller screens.
| Ingredient | Amount | Role |
|---|---|---|
| Ground coffee | 20 g | Dry dose |
| Hot brew water | 180 g | Extracts the coffee |
| Recipe ice | 120 g | Completes the total brew water while chilling |
| Total recipe water | 300 g | 1:15 coffee-to-water ratio |
| Optional serving ice | 40-60 g | Keeps the finished drink cold after brewing |
Separating recipe ice from serving ice prevents a common error. The 120 g in the server is designed to melt. Extra ice added after brewing is not part of the extraction ratio.
How to Make Japanese Iced Coffee
- Prepare the brewer. Put a paper filter in a V60 02 or similar dripper. Rinse it with hot water into a separate vessel, then discard the rinse.
- Measure the recipe ice. Place 120 g ice in the server and set the dripper on top.
- Bloom. Add 20 g medium-fine coffee. Pour 40 g of 94 C water, wetting the bed evenly, and wait 40-45 seconds.
- Complete the pour. Reach 110 g hot water by about 1:15, then finish at 180 g by about 2:00.
- Let it drain. A drawdown around 2:45-3:30 is a useful diagnostic range, not a pass-or-fail target.
- Swirl and serve. Remove the dripper and swirl until the recipe ice has melted. Pour over 40-60 g fresh ice if you want longer-lasting chill.
Finished yield varies because the grounds retain water. Weigh the beverage if exact output matters rather than assuming 300 g reaches the cup.
Calories and Caffeine
Ice and water add no calories, but the amount of brewed coffee that reaches the server depends on how much water the grounds retain. Weigh the finished beverage before publishing a per-serving calorie estimate. If the finished output is M grams and a suitable brewed-coffee reference provides C calories per 100 g, calculate the serving as C x M / 100.
Caffeine also depends on the coffee, dry dose and extraction. It cannot be calculated reliably from the input water, finished beverage weight or serving size, so this recipe does not present an unsupported caffeine total.
Why Hot Brew Over Ice Works
Hot water extracts acids, sugars, aromatic compounds and roast flavors quickly. The measured ice lowers the temperature immediately after extraction. This gives flash brew a different profile from cold brew, which extracts with cool water over many hours.
The result is often bright and aromatic, but the method does not guarantee a particular flavor. Coffee, roast, water and grind still determine the cup.
Grind and Pour Adjustments
Start medium-fine, close to a typical hot V60 grind. Because only 180 g hot water passes through the bed, the recipe needs enough contact and flow resistance to avoid a thin cup.
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| What you taste | What may be happening | First adjustment |
|---|---|---|
| Sour and thin | Flow too fast or grind too coarse | Grind one small step finer |
| Bitter and drying | Flow too slow, excessive agitation or grind too fine | Grind one small step coarser |
| Weak after the ice melts | Too much unmeasured ice or underextraction | Weigh recipe ice and verify the 180 g pour |
| Warm at service | Too little recipe ice or very warm equipment | Use the full 120 g recipe ice and pre-chill the serving glass |
| Cloudy or flat | Heavy agitation or stale coffee | Pour more gently and use freshly roasted coffee |
Change one variable at a time. Keep coffee, total water and recipe ice fixed while dialing the grind.
Japanese Iced Coffee, Flash Brew and Mizudashi
English-language coffee shops often use flash brew for hot coffee brewed onto ice. Japanese sources also describe a rapid-chill method, commonly written as 急冷式アイスコーヒー. Mizudashi refers to extraction with cool water, so it belongs with cold brew rather than this hot-extraction method.
No reliable source reviewed for this guide establishes one inventor or a precise 1960s origin date. The method is well established in Japanese coffee practice, but a confident invention story would go beyond the available evidence.
Best Coffee for Flash Brew
Washed coffees with citrus, floral or stone-fruit character can show their aroma clearly, while chocolate-led coffees produce a rounder cup. Roast labels alone do not settle the choice. Start with a coffee you enjoy hot, then use the grind to tune balance after chilling.
Questions About Japanese Iced Coffee
Is Japanese Iced Coffee Watered Down?
Not when the ice is measured as part of the recipe. The 180 g hot water and 120 g ice together make the intended 300 g total water.
Can I Use a Different Pour-Over Brewer?
Yes. A flat-bottom or other cone brewer can work, but its flow may require a different grind. Keep the 20:300 ratio fixed for the first comparison.
Why Did All the Ice Melt?
That is expected. Recipe ice is supposed to absorb heat and become part of the finished beverage. Add fresh serving ice afterward if needed.
Is Flash Brew Stronger Than Cold Brew?
Neither method has one fixed strength. Compare the actual coffee-to-water ratio and any dilution rather than the names alone.
Research Notes and Sources
The terminology and method are grounded in Japanese sources from Hario, UCC and Kurasu Kyoto. Counter Culture and Blue Bottle provide useful English-language recipe comparisons, not evidence for an inventor or date.