How Long Does Breast Milk Last?
Freshly expressed breast milk lasts up to 4 hours at room temperature, 4 days in the refrigerator, and 6 months in the freezer is best with up to 12 months acceptable. Once frozen milk is thawed in the fridge, use it within 24 hours and never refreeze it. This guide uses the CDC's Proper Storage and Preparation of Breast Milk windows and the AAP's parent storage guidance for practical tips. It is informational only, so follow your pediatrician's advice for your baby.
If you are pumping for bottles, pair storage safety with the right bottle setup. You can compare bottle and nipple flow rates in our database and see the formula twin of this page here: how long is formula good for in a bottle .
Breast Milk Storage Time at a Glance
| Location or situation | How long it lasts | What to remember |
|---|---|---|
| Fresh milk at room temperature (up to 77 F / 25 C) | Up to 4 hours | Use promptly or refrigerate |
| Fresh milk in the refrigerator (40 F / 4 C) | Up to 4 days | Store in the back, not the door |
| Fresh milk in the freezer (0 F / -18 C) | 6 months is best; up to 12 months is acceptable | Freeze in dated 2 to 4 oz portions |
| Previously frozen milk, thawed in the refrigerator | Use within 1 day (24 hours) | Never refreeze thawed milk |
| Leftover milk after a feeding | Use within 2 hours after baby finishes | Discard after that window |
Room Temperature: Up to 4 Hours
Freshly expressed milk can stay at room temperature for up to 4 hours if the room is 77 F / 25 C or cooler. After that, chill or discard it. This is the simplest answer for searches like "how long is breast milk good for?" when the milk was just pumped and has not been refrigerated yet.
Practical tip: label milk with the date it was expressed so you do not have to guess how long it has been sitting out.
Refrigerator: Up to 4 Days
In a refrigerator kept at 40 F / 4 C, freshly expressed milk is good for up to 4 days. Store it toward the back of the fridge, not in the door, where the temperature changes more often.
If you do not expect to use the milk within 4 days, freeze it right away instead of waiting until the end of that window. Small dated containers make it easier to rotate older milk forward first.
Freezer: 6 Months Is Best, Up to 12 Months Is Acceptable
Frozen breast milk keeps best for 6 months, though the CDC says up to 12 months is acceptable at 0 F / -18 C. Freezing preserves safety for much longer than room temperature or refrigeration, but quality is best when you use the milk earlier in that range.
Freeze milk in small 2 to 4 oz portions, label each container with the date, and store it toward the back of the freezer. Smaller portions thaw faster and waste less milk.
Thawed Breast Milk: 24 Hours in the Fridge, Never Refreeze
Once frozen milk is fully thawed in the refrigerator, use it within 24 hours. Do not put it back in the freezer. If you need milk sooner, thaw it under lukewarm running water or in warm water instead of leaving it to chance on the counter.
Use the oldest milk first. That helps you protect quality across your freezer stash and avoids finding a forgotten bag months later.
Leftover Breast Milk After a Feeding: 2 Hours
If your baby starts a bottle of expressed breast milk and does not finish it, use the leftover milk within 2 hours after the feeding ends. After that, discard the remainder. This shorter window is why it helps to pour smaller feeds instead of one oversized bottle.
If you routinely warm bottles, start with a smaller amount and add more only if your baby is still hungry. That cuts down on waste and keeps you inside the safe leftover window.
Colostrum Storage: Same General Rules, Extra Care With Small Volumes
Colostrum follows the same general storage guidance as mature breast milk. Because early pumping sessions often produce small amounts, dated mini-portions help avoid waste and make it easier to use the oldest milk first.
If your baby is premature, hospitalized, or has special feeding instructions, follow your pediatrician's or hospital team's guidance first. Hospitals sometimes use stricter handling rules than home storage guides.
Frequently Asked Questions
How long is breast milk good for?
Freshly expressed breast milk is good for up to 4 hours at room temperature, up to 4 days in the refrigerator, and 6 months in the freezer is best with up to 12 months acceptable.
How long does frozen breast milk last?
At 0 F / -18 C, frozen breast milk is best used within 6 months, though up to 12 months is acceptable. Once it is thawed in the refrigerator, use it within 24 hours.
Can you refreeze breast milk?
No. Never refreeze breast milk after it has thawed.
How long can warmed breast milk sit out?
Once breast milk has been warmed or brought to room temperature, use it within 2 hours. If your baby already drank from the bottle, use the leftover milk within 2 hours after the feeding ends.
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