Rule of thumb · PhysicsNº 94 / 167

Ice water beats freezer air

An ice-water bath chills a can 5–10× faster than freezer air.

Why it works

Water conducts heat away far better than air — convective transfer is an order of magnitude stronger. Add salt and stir to go faster still.

When it fails

Only because of contact, not temperature — the ice water is warmer than the freezer. Add salt and it gets faster still. But for something that must not get wet, or a large thermal mass where internal conduction is the bottleneck, the advantage largely disappears.

Do it exactly

Estimate with the rule, then check it against the calculator that models it properly.

Open Beverage Cooling Simulator →

More in Physics

← PreviousCooling closes the gap in equal fractions Next →Smash factor tops out near 1.5

What is the fastest way to chill a drink?

An ice-water bath chills a can 5–10× faster than freezer air. Water conducts heat away far better than air — convective transfer is an order of magnitude stronger.

Browse all 167 rules of thumb →