Breast milk storage time calculator
Enter when the milk was pumped or thawed and how it is stored to get the latest time to use it.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter date pumped or thawed, time and storage.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Use by = start time + duration: room at 25°C (77°F) or cooler: 4 hours. Fridge at 4°C (40°F): 4 days. Freezer at -18°C (0°F): within 6 months for top quality, up to 12 months acceptable. Thawed at room temperature: 1 to 2 hours; thawed in the fridge: 24 hours. Leftovers: 2 hours.
Example
Inputs: Date pumped or thawed = 2026-09-30, Time = 10:00, Storage = Fresh milk in the fridge. Result: Use by: 2026-10-04 10:00; Latest acceptable: 2026-10-04 10:00; Rule applied: Fridge at 4°C (40°F): up to 4 days.
Limits and caveats
- These times are for healthy full-term babies; they may be shorter for premature babies or in hospital.
- Keep milk at the back of the fridge or freezer, not in the door, where temperature swings.
Questions about this tool
Can I refreeze thawed milk?
No. CDC guidance says thawed breast milk should never be refrozen.
How should I thaw frozen milk?
In the fridge overnight, under warm running water or in a bowl of warm water. Avoid the microwave, which heats unevenly.
Can I add fresh milk to chilled milk?
Cool the fresh milk first, then combine, and date it by the oldest milk.