ChillTest: Cool Box Ice TestChillTest: Cool Box Ice Test
Every cool box promises days of ice. Weigh the meltwater and find out what yours actually manages.
Download on the App StoreFeatures
One figure for your cool box
Load it with ice, leave it a few hours, then weigh the water that has collected. ChillTest turns that into a single heat-loss figure in watts per degree, which belongs to the box rather than to the afternoon you tested it.
Measured, not estimated
While ice is thawing, the inside of a cool box sits at 0°C, and melting a kilogram of ice takes a fixed 333.55 kJ. Every gram of meltwater therefore stands for a known quantity of heat that has got in.
Kitchen scales and nothing else
No thermometer to buy, no sensor to pair, nothing left sitting in the box. A measuring jug does the job just as well.
Planning answers for the actual trip
How long 5 kg of ice lasts at 30°C, how much ice a weekend at a festival needs, whether the pricey box really beats the cheap one. Allow for how often the lid opens, sun on the lid and how full the box is packed.
It will not hand you a wrong number
If the ice thawed completely, if ice packs were used in place of ice, or if it was barely warmer outside than in, the run does not count as a measurement and no figure is shown. You are told what went wrong and what to change.
Compare the boxes you already own
Keep a record for each cool box and cool bag, with its own measurement history, sorted best first. It is your ranking, from your conditions, not a manufacturer's claim.
Every cool box claims to keep ice for days. ChillTest lets you find out what yours actually manages — with a kitchen scale and a bag of ice.
No thermometer. Nothing to pair. Just meltwater on a scale.
HOW IT WORKS
While ice is melting, the inside of a cool box sits at exactly 0°C. That turns the meltwater into a measuring instrument: every gram that melts stands for a known amount of heat that got in. Weigh the water, tell ChillTest how long the box sat and how warm it was outside, and the app works out one figure for that box — its heat leak, in watts per degree.
The figure belongs to the box itself, not to the afternoon you measured it. Once you have it, ChillTest answers the questions that actually come up:
• How long will 5 kg of ice last at 28°C?
• How much ice should I take for a weekend at a festival?
• Is the expensive box genuinely twice as good as the supermarket one?
NOTHING TO BUY
A kitchen scale or a measuring jug is all you need. No thermometer, no sensors, nothing left sitting inside the box.
ANY ICE YOU HAVE
Block ice, cubes, crushed, frozen bottles — set the amount by weight, by volume or by counting pieces. Ice taken straight from a freezer is below 0°C and lasts a little longer; ChillTest allows for that as well.
IT TELLS YOU WHEN A MEASUREMENT DOES NOT COUNT
This is the part most guides skip. If the ice melted away completely, the box never held 0°C and the result means nothing — so ChillTest declines to show a figure rather than show a wrong one. Same when the box was not pre-chilled, when the run was too short, or when an ice pack was used instead of ice. Every warning explains what went wrong and what to change.
COMPARE YOUR OWN BOXES
Keep as many boxes and cool bags as you like, each with its own measurement history. They sort best first, so the ranking is yours — measured in your conditions, not copied off the packaging.
WHAT YOU GET
• One performance figure per box, with an estimated range
• Ice-remaining curves for any temperature and any amount of ice
• Required-ice calculator for a target number of hours
• Adjustments for lid opening, sun and how full the box is
• A step-by-step measuring guide explaining why each step matters
• Metric or imperial, grams or ounces, °C or °F
• Works entirely offline; nothing leaves your device
GOOD FOR
Camping and caravanning, festivals, fishing, picnics, days at the beach, the big shop in summer, and anyone weighing up whether the pricier box is worth it.
These are physical estimates for planning and comparison. Real trips vary with how often the lid is opened, where the box sits and what goes inside. ChillTest measures how quickly ice melts — it is not a food-safety device and does not tell you whether food is safe to eat.