The short answer: a closed refrigerator keeps food safe for about 4 hours. A full, closed freezer keeps food safe for about 48 hours — about 24 hours if it's half full.
Those numbers come with one condition that most families break in the first hour: the door has to stay shut. Every time someone opens it to check, cold air spills out and the clock runs faster.
The rules, in order
- The moment the power dies: close the fridge and freezer and tape a note on the door if you have to. This is the single highest-value move in a blackout kitchen.
- Fridge — 4 hours. After that, perishables (meat, dairy, eggs, leftovers, cut produce) are no longer safe. Hard cheeses, butter, condiments, and whole produce last longer.
- Freezer — 48 hours full, 24 half-full. A packed freezer holds its cold far better. If a storm is forecast, fill empty freezer space with bottles of water — more thermal mass, plus emergency ice.
- When power returns: if food still has ice crystals or reads 40°F or below, it's safe to refreeze or cook. When in doubt, throw it out — no meal is worth 48 hours of food poisoning during a blackout.
What about coolers?
If the outage will clearly outlast 4 hours, move the most valuable perishables to a cooler with ice once, in a single organized transfer. One planned opening beats five curious ones.
The bigger picture
Food is actually the third problem in a blackout. Water and light come first — a family can improvise meals for days, but not clean water or a lit stairwell. Our free Blackout Playbook walks the first 72 hours hour by hour, and the 72-Hour Blackout Kit covers the four essentials in one box.