FIXIF Crate-Series
How Long Does Ice Last in a Cooler?
The honest answer — and the seven variables that move it by days.
Marketing promises ten days. Reality lands between two and eight depending on what you do before, during and after you close the lid. Here is what actually moves the needle in a rotomolded hard cooler.
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The honest numbers
36 L rotomolded crate, 2:1 ice ratio, lid sealed, kept in shade, opened twice a day at 25 °C ambient: 4–6 days of usable ice. Below 15 °C ambient: 7–10 days. In direct sun on a 35 °C day: 2–3 days.
Retention scales with volume: a 24 L crate loses ice about 30% faster than a 51 L crate under identical conditions.
The seven variables
1. Pre-chill the crate. A warm body cools itself first and costs you the first 8–12 hours. Sacrifice a bag of ice the night before.
2. Use the 2:1 rule. Two parts ice to one part contents by volume.
3. Block ice beats cubes. Less exposed surface means slower melt — a frozen 5 L bottle is free block ice and drinking water on day three.
4. Pre-chill the contents. Warm drinks melt ice; refrigerate everything before it goes in.
5. Keep the meltwater. 0 °C water holds cold better than 25 °C air — only drain when the crate is more than half empty.
6. Keep it shut. Every opening swaps cold air for warm air. Pack so you find things on the first try.
7. Keep it shaded. Direct sun on a dark shell can add 10 °C to the body. Under a tarp or in a footwell, not in an open truck bed.
What the construction contributes
A seamless rotomolded shell with pressure-injected polyurethane and a full-perimeter freezer gasket removes the thermal shortcuts that cost cheaper coolers a day or more. Everything above is what you add on top of that baseline.
Questions
Should dry ice be used?
Only with ventilation and never sealed airtight — sublimating CO₂ builds pressure. For most trips, block ice is safer and simpler.
Do ice packs work as well as ice?
They hold temperature well but carry less total cooling energy than the same volume of water ice. Use them to supplement block ice, not to replace it.