Support

• Why must I pre-chill the box for an hour before starting?

  A cool box at room temperature spends its first ice cooling its own walls. On an 8 kg box that is roughly 720 g of extra melt, against perhaps 97 g of genuine melt in an hour — enough to skew the result several times over. The hour of pre-chilling, with that water tipped away, keeps the walls out of the sums.

• Why does the test need to run for at least three hours?

  Weighing error does not shrink with time, so a brief run makes it loom large. Over one hour, a ±20 g slip scatters the prediction between 1.8 and 2.7 days. Over three hours the same slip narrows the spread to around 0.15 days, which is why three hours is the sensible minimum.

• Can I use ice packs rather than ice?

  No, and the app will tell you so instead of producing a figure. The method relies on the contents holding at exactly 0°C as they thaw. Gel packs are made to change phase at a different temperature, so the arithmetic no longer applies. It has to be plain water ice.

• Do I need a thermometer?

  No. Kitchen scales are enough, or a measuring jug if you would rather work in millilitres. You do need the outside air temperature — type it in, or let the app fetch it for your area.

• Does it tell me whether the food inside is still safe?

  No. ChillTest answers one question only: how long ice lasts in your box. It is not a food-safety device, it does not know what is inside or how warm it became, and it makes no claim about whether anything is fit to eat. Follow proper food hygiene guidance for that.