What is the difference between cold brew and iced coffee?

Cold brew extracts in cold water over many hours. Iced coffee is brewed hot and chilled — in the Japanese method, directly onto ice so the melt is counted as part of the brew water.

Is cold brew less acidic than hot coffee?

Research finds real sensory differences but not the simple story marketing tells. One controlled comparison found cold brew more floral and less bitter, sour and rubbery, while SCA research found extraction behaviour varying with temperature, origin and roast.

How long does cold brew keep?

CupTune makes no shelf-life prediction. FDA guidance is to refrigerate prepared food within two hours and keep the refrigerator at or below 4 °C; beyond that, judgement about your own batch is yours.

What ratio should I use for Japanese iced coffee?

Use your normal brew ratio, then split the water between hot water and ice. For a 1:16 brew with 20 g of coffee, that is 320 g of total water, commonly around 200 g hot and 120 g as ice.

Two different drinks

Cold brew is not iced coffee

Cold brew and iced coffee are not the same thing made two ways. They differ in method, in what research finds about their taste, and in how long they last.

Cold brew extracts slowly in cold water and is diluted at serving. Japanese iced coffee brews hot directly onto ice, so the melt is part of the recipe rather than an accident.

Cold brew: cold water, hours

Coffee steeped in cold or room-temperature water for eight to twenty-four hours, then filtered. Low temperature extracts slowly and selectively, so the balance of what ends up dissolved differs from a hot brew — not merely the same coffee served cold. CupTune's batch calculator sizes it to your vessel and our cold brew recipes cover ready-to-drink and concentrate.

Japanese iced: hot water, straight onto ice

Brew hot as normal, but replace part of the brew water with ice in the carafe, so the hot coffee is chilled the instant it is made. Aromatics that would evaporate during a slow cool-down are trapped. It takes four minutes rather than sixteen hours, and it tastes much more like the hot brew of the same coffee — because it is one.

The important detail is that the ice is part of the recipe. If your ratio is 1:16 and you want 320 g of water, you use roughly 200 g hot and 120 g as ice, not 320 g hot poured over ice you did not count.

What the sensory research says

The popular claim is that cold brew is sweeter and less acidic. SCA cold-brew sensory research tested that claim directly and found the picture more complicated, with extraction behaviour varying by temperature, origin and roast. A sensory comparison of cold and hot full-immersion brews compared full-immersion brews and found cold brew more floral and less bitter, sour and rubbery than hot brew of the same coffees, and a sensory study of hot, room-temperature and cold immersion brews over time tracks how those profiles shift with time.

So there is a real, measurable difference. It is just not reliably the one the marketing claims, and it depends on which coffee you used.

Keeping it

Cold brew is a prepared food sitting at a friendly temperature for a long time, which is the one place in coffee where handling genuinely matters. FDA food storage guidance says to refrigerate prepared food promptly, within two hours, and to keep a refrigerator at or below 4 °C. CupTune makes no shelf-life prediction and no microbial safety assessment; if you are steeping at room temperature, that is a decision you are making, not one this site is endorsing.

Which one to make

Want it now, and want it to taste like your coffee? Japanese iced. Want a batch in the fridge for the week, and like the rounder profile? Cold brew. They are different drinks, and preferring one is not a mistake about the other.