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Compare milk storage times
It's 3 AM and there's a bottle on the counter — how long has it been there? Compare elapsed storage time with CDC guidance. The result cannot verify handling or temperature.
Within the time guideline
Fresh breast milk keeps in the refrigerator for up to 4 days. Store it toward the back, not in the door.
Sources and assumptions
Time limits summarize CDC guidance for healthy, full-term babies. The result assumes the selected temperature has been maintained. Timing alone cannot establish whether milk is safe; handling, thawing, and contact with a feeding bottle also matter. Formula mode is only for bottles where feeding has not started: discard formula left after a feed.
Prepared by the Milk & Minutes Editorial Team. This calculator has not been independently reviewed by a clinician. Editorial standards.
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Breast milk storage chart (CDC)
Breast milk and formula storage guidelines (CDC). Room temperature means up to 77°F / 25°C.
| Milk type | Room temperature | Refrigerator (40°F) | Freezer (0°F) |
|---|---|---|---|
| Freshly expressed breast milk | Up to 4 hours | Up to 4 days | Best within 6 months; up to 12 months acceptable |
| Thawed breast milk (previously frozen) | 1–2 hours | Up to 24 hours | Never refreeze |
| Leftover breast milk from a feeding | Within 2 hours of the feeding | Within 2 hours of the feeding | Never freeze |
| Prepared formula — feeding not started | Within 2 hours of preparing | Up to 24 hours | Never freeze |
Common questions
How long can breast milk sit out at room temperature?
Freshly expressed breast milk is safe at room temperature (up to 77°F / 25°C) for up to 4 hours. Thawed milk should be used within 1–2 hours, and milk left over from a feeding within 2 hours of the start of that feeding.
How long does breast milk last in the fridge?
Freshly expressed breast milk keeps for up to 4 days in a refrigerator at 40°F (4°C). Store it toward the back of the fridge — not in the door, where temperature swings with every opening. Thawed milk lasts only 24 hours in the fridge.
Can I refreeze breast milk after it has thawed?
No. Once breast milk has thawed, it should never be refrozen. Use thawed milk within 24 hours (refrigerated) or 1–2 hours at room temperature.
Can my baby finish a bottle later?
Once your baby has drunk from a bottle, bacteria from their mouth enter the milk. Use the leftover milk within 2 hours of the start of that feeding, then discard it — refrigerating it doesn't reset the clock.
How long is prepared formula good for?
Use prepared formula within 2 hours of mixing it, or within 1 hour once a feeding has started. Untouched prepared formula can be refrigerated for up to 24 hours. Never freeze formula.
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This tool provides general educational guidance based on published guidelines. It is not medical advice. Always follow the recommendations of your pediatrician, lactation consultant, or healthcare provider — especially for premature babies, low-weight babies, or babies with health conditions.