Tool · iced pour-over
Iced pour-over: how much hot water, how much ice
Japanese-style iced coffee is a pour-over brewed hot straight onto ice in the carafe. Part of the brew water goes in as ice instead of hot water, so the melting ice chills and dilutes the coffee to drinking strength. Published recipes put 25–50% of the water in the carafe as ice. The calculator below splits any dose that way and checks whether the ice can melt.
The short answer
- Total water (hot water + ice) ≈ 10 to 17 × the coffee in the published recipes below, most between 13 and 17 ×; 15 × is a central value.
- Ice share 25–50% of that total, most often 30–40%. Peter Giuliano, writing in Fresh Cup in 2014, says he could replace “between twenty and fifty percent” of the brew water with ice without dramatically changing extraction.
- Hot water is the rest, so the hot-water ratio alone is strong, about 1:7.4 to 1:11. Counter Culture describes its recipe as “a 1:11 coffee-to-water ratio, plus ice for dilution.”
- Grind a little finer than usual: “medium-fine” (Counter Culture, Blue Bottle, Kurasu, La Cabra) or “one notch finer” than your usual pour-over (Devoción).
Iced pour-over calculator
total = 30 × 16.67 = 500 g · ice = 500 × 33% = 165 g · hot = 500 − 165 = 335 g · hot-water ratio = 335 ÷ 30 ≈ 1:11.2 · 500 g ≈ 16.9 fl oz
Melt check at 200 °F (93.3 °C): the hot water could melt at most ≈392 g of ice, so all 165 g can melt; if it all did, with no heat lost, the mix would be ≈36 °C (97 °F). Real brews lose heat to the grounds, brewer, carafe and air, so expect colder coffee and possibly some ice left.
The formula
ice = T × s (s = ice share, e.g. 0.33)
hot water = T − ice = T × (1 − s)
hot-water ratio = hot water ÷ coffee = R × (1 − s)
coffee = T ÷ R (if you start from the drink size)
fl oz ≈ grams ÷ 29.57 (1 ml of water ≈ 1 g)
Worked example, Counter Culture’s recipe: 30 g of coffee, 335 g of hot water and 165 g of ice make 500 g of total water, ≈1:16.7 overall. The ice is 165 ÷ 500 ≈ 33% of it, and the hot water alone is 335 ÷ 30 ≈ 1:11.2, the “1:11” the roaster quotes. For a recipe at the SCA’s 55 g/L reference (≈1:18.2), set R to 18.2; the published iced recipes below all run stronger than that.
Eight published recipes, side by side
All coffee, water and ice weights below are from the recipe pages listed in the sources. Totals, shares and ratios are our arithmetic; 1 ml of water is counted as 1 g.
| Recipe | Coffee | Hot water | Ice | ≈ Ice share | ≈ Hot ratio | ≈ Total ratio | Water temp. |
|---|---|---|---|---|---|---|---|
| Counter Culture, Flash Brew | 30 g | 335 g | 165 g | 33% | 1:11.2 | 1:16.7 | 200 °F |
| Equator, Cold Chemex | 40 g | 350 g | 250 g | 42% | 1:8.8 | 1:15 (stated) | not stated |
| Peter Giuliano, Fresh Cup (2014) | 32 g | 300 g | 200 g | 40% | 1:9.4 | 1:15.6 | not stated |
| Devoción, Flash Brew | 40 g | 300 ml | 200 g | 40% | 1:7.5 | 1:12.5 | 205 °F |
| Nossa Familia, Japanese style | 34 g | 270 ml | 270 g | 50% | 1:7.9 | 1:15.9 | “just off the boil” |
| Kurasu, V60 (2024) | 16 g | 150 g | 70 g | 32% | 1:9.4 | 1:13.8 | 91 °C (196 °F) |
| La Cabra, V60 | 18 g | 180 g | 60 g | 25% | 1:10 | 1:13.3 | 96 °C (205 °F) |
| Blue Bottle, Hot over ice | 20–27 g | 200 g | ≈75 g | 27% | 1:7.4–1:10 | 1:10.2–1:13.8 | 200–210 °F |
The pattern is consistent: the hot water alone carries about 1.5 to 2 times as much coffee per gram as a normal pour-over (compare the 1:15–1:17 most hot recipes use in the pour-over ratio guide), and the ice brings the total back to roughly 1:10–1:17. In the calculator presets, the kettle temperature is the recipe’s own where it gives one and the SCA’s 200 °F otherwise.
- Hot water: 335 g at 200 °F, poured in stages as for a hot pour-over.
- Coffee bed: 30 g, ground medium-fine.
- Ice: 165 g, put in the carafe before brewing.
- Brew onto ice: the coffee drips onto the ice, which chills it and dilutes it as it melts.
- Total water: 335 + 165 = 500 g, ≈1:16.7 against 30 g of coffee.
- The split: ≈67% hot water and ≈33% ice; the hot water alone is ≈1:11.2.
Will the ice melt? The energy check
Melting ice takes a lot of heat. Melting 1 g of ice at 0 °C absorbs 333.55 J, while cooling 1 g of water by 1 °C releases only about 4.18 J. So hot water at 93 °C (200 °F) can melt at most about 4.18 × 93 ÷ 333.55 ≈ 1.17 times its own weight of ice, and only if it loses heat to nothing else. The calculator’s melt check uses:
mix temperature ≈ (4.18 × hot × T − 333.55 × ice) ÷ (4.18 × total)
T = kettle temperature in °C; coffee treated as water; ice at 0 °C
These are upper limits (our arithmetic, not a measured result). In a real brew, some heat goes into the grounds, dripper, carafe and air, the grounds hold back some water, and freezer ice starts below 0 °C. For Counter Culture’s 33% ice, the ideal mix would still be about 36 °C (97 °F), which is why its recipe ends “Pour over more ice.” Blue Bottle expects its ice to be “fairly melted” by the end and serves over fresh ice; Kurasu says to melt all the ice before serving. Devoción’s advice when ice is left over: stir, use smaller cubes, or use less ice and add the difference as hot water. At Nossa Familia’s 50% ice, there is little heat to spare: the ideal mix would be about 10 °C (50 °F) even with water at 212 °F.
Step by step
- Pick a dose and total ratio. 30 g at 1:15–1:17 makes about 450–500 g, Counter Culture’s “one, 16 oz cup” (500 g ≈ 16.9 fl oz).
- Choose the ice share. Start at about one third; go toward 40–50% for a colder drink with more dilution, toward 25% for a stronger one.
- Weigh the ice into the carafe before brewing. La Cabra says not to preheat the pitcher, since it is there to cool the coffee.
- Grind a little finer than for a hot brew of the same dose. With less water passing through, Nossa Familia suggests a finer grind and a longer brew; recipes above aim for about 1:45 to 4 minutes in total.
- Rinse the filter and pour the rinse water away, not into the ice.
- Brew as usual with only the hot water: bloom, then pulse pours (bloom and pour weights for any dose: pour schedule generator). Tare the scale with the ice in the carafe so it reads hot water only.
- Swirl until the ice is melted or nearly so, then serve over fresh ice.
Where the sources disagree
| Question | What the sources say |
|---|---|
| How much water to swap for ice | Giuliano’s 2014 article gives two ranges: “between twenty and fifty percent” in one passage, “thirty to fifty percent” in another. The recipes above use 25–50%. |
| What “the ratio” means | Counter Culture quotes the hot-water ratio (1:11) and adds ice on top; Equator quotes the total (1:15, hot water plus ice). Always check which one a recipe means. |
| Melt it all or not | Kurasu: melt all the ice before serving. Blue Bottle: “fairly melted”. Counter Culture and Blue Bottle serve over more ice. |
| Water temperature | 91 °C (Kurasu) to 210 °F (Blue Bottle) or “just off the boil” (Nossa Familia); the SCA hot-brew range is 200 °F ± 5°. |
Iced pour-over, cold brew and chilled hot coffee
Wikipedia’s iced coffee article describes the Japanese method as brewing with hot water that drips over ice cubes, in which the volume of hot water “is reduced to account for the dilution of the coffee by the melting ice”. It says iced coffee has been drunk in Japanese coffeehouses since the Taishō period (around the 1920s). Giuliano describes Japanese equipment “designed to chill hot coffee instantly,” and credits Hidetaka Hayashi of the Hayashi Coffee Institute for teaching him the method.
The research compares cold brew with hot brew, not with brewing onto ice specifically. In research summarised by William Ristenpart in the SCA’s 25 magazine, hot brews made at 92 °C and then chilled were compared with cold brews at matched strength: the cold brews were “more floral and less bitter, less sour, and less rubbery,” and about 0.1–0.2 pH units higher. A 2018 Scientific Reports study found similar pH in hot and cold brews (4.85–5.13), but higher titratable acidity in the hot brews. An iced pour-over is a hot extraction, so expect it to taste like chilled hot coffee, not like cold brew. For steep times, concentrate ratios and storage, see the cold brew guide.
Checklist
- Total water (hot + ice) decided: about 10–17 × the coffee
- Ice share chosen: 25–50%, one third to start
- Ice weighed into an unheated carafe
- Scale tared with the ice on it
- Grind one step finer than your hot recipe
- Only the hot water poured through the coffee
- Swirled until the ice is (nearly) melted; served over fresh ice
- Logged both numbers: hot water and ice
Lab tip: write iced recipes as three weights, “30 g · 335 g hot · 165 g ice”. A single ratio cannot tell you how much of the water was ice. For the hot-brew basics behind this page, see the coffee-to-water ratio guide, grind size chart and water temperature.
Sources
- Peter Giuliano — Discovering Japanese Iced Coffee. Fresh Cup, 14 July 2014 (aisu kohi; replace 20–50% / 30–50% of brew water with ice; 32 g, 300 g water, 200 g ice; 3–4 min)
- Wikipedia — Iced coffee (secondary: Japanese hot-onto-ice method, hot water reduced for melting ice; Taishō-period coffeehouses; double-strength method)
- Counter Culture Coffee — Flash Brew (30 g, 335 g water at 200 °F, 165 g ice; “1:11 coffee-to-water ratio, plus ice for dilution”; one 16 oz cup)
- Blue Bottle Coffee — Hot over ice brew guide (20–27 g, 200 g water at 200–210 °F, about 75 g ice, 1:45–2:15)
- Kurasu (Kyoto) — Japanese brew guide on iced pour-over coffee, 2024 (V60: 16 g, 150 g water at 91 °C, 70 g ice; melt all the ice before serving)
- La Cabra — Iced coffee brew guide (V60: 18 g, 180 g water at 96 °C, 60 g ice, 2:30; do not preheat the pitcher)
- Devoción — Flash brew iced coffee brew guide (40 g, 300 ml water at 205 °F, 200 g ice; one notch finer; unmelted-ice advice)
- Equator Coffees — Cold Chemex recipe (40 g, 350 g hot water, 250 g ice, 600 g total, 1:15)
- Nossa Familia Coffee — Brewing recipe: Japanese style iced coffee (34 g, 270 ml water just off the boil, 270 g ice, about 4 min)
- Specialty Coffee Association — Protocols & Best Practices (55 g/L ± 10%; 200 °F ± 5° / 93.0 °C ± 3° at the point of contact)
- Ristenpart W.D. — Worth the Wait: How Cold Brew Differs from Chilled Hot Brew. SCA 25 Magazine, Issue 22 (hot brews at 92 °C chilled to fridge temperature; sensory and pH results)
- Rao N.Z., Fuller M. (2018) Acidity and Antioxidant Activity of Cold Brew Coffee. Scientific Reports 8 (Jefferson Digital Commons record; pH 4.85–5.13; hot brews higher titratable acidity)
- Wikipedia — Enthalpy of fusion (ice: 333.55 J/g; water: 4.18 J/(g·K))
- NIST Office of Weights and Measures — Approximate Conversions (1 fl oz = 29.57 mL)