Cold brew vs. iced coffee

What cold water leaves behind

Sourced

Cold water extracts far more slowly than hot, which is why cold brew needs hours where hot coffee needs minutes. Two studies from one research group compared hot and cold brews of the same coffees. In both, the cold brews held less total acid than the hot ones. In the first their pH was about the same; in the second, on one coffee at three roast degrees, the cold brews were somewhat higher in pH, meaning less acidic, and held less dissolved material. The second study concluded that cold water extracts some compounds less effectively.

Neither study tasted anything. That cold brew is mellower, often chocolatey or nutty, with less of the high-toned fruit or floral character of a hot brew, is how drinkers and makers describe it; it is consistent with the lower total acid and has not been shown by a panel in what was read. Whether it is better depends on the coffee and on what you like.

The third option: brewing hot onto ice

Widely documented

The weakness of ordinary iced coffee is dilution. Hot coffee poured over ice melts it, and the drink ends up watery. The usual answer is to brew hot coffee directly onto ice at a stronger ratio, counting the ice as part of the brewing water, so that the melt brings it to normal strength. This is often called flash brew or Japanese-style iced coffee.

It keeps the aroma and acidity of a hot brew while chilling it within seconds, and it takes five minutes instead of a day.

Time, ratio and keeping

Typical range

Cold brew recipes vary enormously, from ready-to-drink strength to heavy concentrates. No single ratio is standard.

Which has more caffeine

CoffeeHQ explanation

Cold water is not better at extracting caffeine than hot water; if anything it is slower. Cold brew is often higher in caffeine per glass because it is made with more coffee for the amount of water and is not always diluted much.

A cold-brew concentrate cut one-to-one with water or milk can easily contain more caffeine than a glass of iced filter coffee. The same concentrate diluted further may contain less. The figure on any particular drink depends on the recipe, so treat general claims with caution.

Choosing by what matters to you

Tendency, not a guarantee

Low acidity and smoothness

Cold brew. It is also the more forgiving of the two with darker or older coffee.

The character of a good light roast

Iced coffee brewed hot onto ice, which keeps the aromatics cold brew tends to lose.

Convenience through the week

Cold brew. One batch keeps in the fridge and takes seconds to serve.

A cold coffee right now

Iced coffee. Cold brew cannot be hurried.

What to do next

• Cold-brew batch and dilution calculator — Works out concentrate, dilution and serving size for the strength you want.
• Cold brew guide — A starting recipe, steep times and how to fix a weak or bitter batch.
• Iced coffee — How to make it without ending up with a watery glass.
• Caffeine estimator — Estimates caffeine from the recipe instead of from the name of the drink.