Your cooler says it holds ice for days. Weigh the meltwater and find out what it actually does.

Features

• One number for your cooler

  Load it with ice, leave it a few hours, then weigh the water that has collected. ChillTest converts that into a single heat-leak figure in watts per degree, which belongs to the cooler itself rather than to the day you tested it.

• Measured, not estimated

  While ice is melting, the inside of a cooler sits at 0°C, and melting a kilogram takes a fixed 333.55 kJ. Every gram of meltwater represents a known amount of heat that got in, which is what makes this a measurement.

• A kitchen scale is the whole kit

  Nothing to buy, nothing to pair, nothing left inside the cooler. A measuring cup works just as well if that is what is in the drawer.

• Answers for the trip you are packing for

  How long 5 kg of ice lasts at 30°C, how much ice a weekend at the cottage needs, whether the expensive cooler really doubles the cheap one. Account for lid opening, sun and how full the cooler is packed.

• It refuses to show a wrong number

  If the ice melted out, if ice packs were used in place of ice, or if it was barely warmer outside than in, the run is not a valid measurement and no figure appears — just an explanation of what to change.

• Rank every cooler you own

  Keep as many coolers as you like, each with its own measurement history, sorted best first. The ranking comes from your conditions, not from a spec sheet.