Why It Works
- Using a scale makes the process easy and accurate.
- Blooming the coffee by wetting the grounds and then waiting 30 seconds before proceeding allows them to de-gas, which improves flavor extraction.
- Brewing hot coffee directly onto ice produces iced coffee that's fresh and flavorful, not stale or muddy.
Want some good news? The easiest way to make iced coffee also turns out to be the best. At least, that's what our panel of blind tasters agreed when we pitted Japanese-style iced coffee against cold brew and leftover hot-brewed coffee. More specifically, the tasters preferred Japanese-style iced coffee when drinking it black (cold brew came out on top when mixed with milk).
Of course coffee is a complicated concoction with a ridiculous number of variables, from bean type and roast level to grind size, brewing method, water temperature, and more—which is to say, this is not a topic that can be reduced to an easy set of answers. Still, Japanese-style iced coffee has a lot going for it.
What Is Japanese-Style Iced Coffee
Japanese-style iced coffee is simply coffee that is brewed hot directly onto ice, which chills it rapidly. Exactly how you do this is up to you. You can brew the coffee in any number of pour-over devices, whether a Hario V60, Melitta pour-over cone, Kalita Wave, Chemex, etc. In each case, you'll need to set the dripper over a vessel that's large enough to contain your ice and the brewed coffee.
You can even use an electric coffee brewer, with ice in the machine's carafe. There's a ton of coffee-brewing gear out there, and much of it can be made to work for Japanese-style iced coffee.
What Makes Japanese-Style Iced Coffee So Good?
Cold brew coffee is often celebrated for its flavor, which is round and sweet and low in acid. And while that can be good (especially when blended with rich dairy or a dairy substitute), it can often fall short when served black—that's because some level of brightness in a cup of coffee can be a good thing, balancing out coffee's darker, roasted flavor notes.
This flavor difference comes down to some basic science: Hot water has more energy than the cold water used to make cold-brew, which means the molecules in a kettle of hot water are moving around more quickly than the molecules in cold water. By moving more quickly, they're able to extract more soluble compounds (read: flavor) from the ground coffee more quickly. This produces a cup of coffee that most of our blind tasters found to be better balanced (compared to cold brew) and more delicious.
But that alone doesn't explain why Japanese-style iced coffee is so good, because according to that logic, any coffee that's brewed hot should make great iced coffee when chilled (essentially, leftover hot coffee repurposed for iced coffee later). But in our tests, coffee that was brewed hot and then allowed to cool down more slowly before being chilled in the refrigerator produced a cup that tasted more stale.
Which takes us to the second part of Japanese-style iced coffee's success: brewing directly onto the ice. By rapidly chilling the freshly brewed coffee, its bright, clean, and just-made flavor is preserved, and it's a difference you really can taste.
And of course we can't talk about Japanese-style iced coffee's benefits without also pointing out that it's one of the easiest ways to make iced coffee. Where both cold brew and the leftover approach require planning at least many hours if not a full day in advance, Japanese-style iced coffee can be made in just minutes with barely any extra effort.
The Key to Great Japanese-Style Iced Coffee
The key to making great Japanese-style iced coffee is to get your ratios right. Because you're brewing onto ice, which is going to melt and dilute your brew, you need to account for that in your measurements by brewing a double-strength batch of coffee and chilling it with just enough ice to achieve your desired final brew strength.
So, for example, in this recipe we make 16 fluid ounces of brewed iced coffee by brewing a double strength batch using one ounce of ground coffee and eight ounces of hot water. This is brewed directly onto an additional eight ounces of ice, which will melt to dilute the coffee properly.
The easiest way to do this is with a scale, though with a little tinkering you certainly could figure out a scoops-to-hot-water-to-number-of-ice-cubes recipe that works at your house. A scale, though, is by far the easiest way to do it, and so it's how the recipe is written here.
8 ounces (225g) ice
1 ounce (30g) medium-coarse ground coffee (about the size of Diamond Crystal kosher salt)
8 ounces (225g) near-boiling water (roughly 200°F/93°C)
Set a carafe large enough to hold 16 fluid ounces (475ml) of brewed coffee on a digital scale and tare scale to zero. Add 8 ounces (225g) ice. Set a dripper cone on top. Line with paper filter and add the ground coffee. Tare scale to zero once more.
Pour just enough near-boiling water onto grounds to wet them, then let stand 30 seconds (this is called blooming the coffee and will improve the flavor of the final brew). Resume pouring near-boiling water all over grounds until the scale reads 8 ounces (225g). Allow water to fully drain through filter, then discard used coffee grounds. Serve iced coffee right away.
Digital scale, pour-over coffee brewer of your choice along with paper filters that fit your brewer
You can also use an electric coffee brewer: Simply fill the carafe with the correct amount of ice, then set up your brewer with the correct amount of coffee and fill the water tank with the correct amount of water, then brew the coffee; if your coffee maker has a warming plate, be sure to turn it off.
Make-Ahead and Storage
Japanese-style iced coffee is best enjoyed freshly brewed.