How long the cold holds
USDA guidance: a full freezer holds a safe temperature about 48 hours; a half-full freezer about 24 hours — if the door stays closed. A chest freezer beats an upright; a freezer in a cool basement beats one in a hot garage. Grouping food into a tight block helps it protect itself.
The refreeze test
When power returns, check food item by item: anything that still contains ice crystals or reads 40 °F (4 °C) or below may be safely refrozen or cooked — with some quality loss. Anything above 40 °F for more than 2 hours: discard. Partial thawing and refreezing costs texture, never safety, when the temperature rule was met.
What not to do
- Don’t open the door to check “just for a second” during the outage — every opening spends the cold reserve.
- Don’t judge by appearance or smell; frozen food can look normal after an unsafe excursion.
- Don’t refreeze anything that was warm to the touch.
Walk each doubtful item through the Power-Outage tool.