How long does breast milk last?
Freshly pumped breast milk keeps for up to 4 hours at room temperature, up to 4 days in the fridge and about 6 months in the freezer. Thawed and leftover milk follow shorter clocks, and those are the ones most of us forget.
The short version, from the CDC:
Room temperature (77°F or colder): up to 4 hours.
Refrigerator: up to 4 days.
Freezer: about 6 months is best, up to 12 months is acceptable.
Breast milk storage chart
| Type of milk | Room temperature | Refrigerator | Freezer |
|---|---|---|---|
| Freshly pumped | Up to 4 hours | Up to 4 days | About 6 months is best, up to 12 months acceptable |
| Thawed in the fridge | Use within 2 hours once brought to room temperature or warmed | Use within 24 hours | Never refreeze |
| Left over after a feed | Use within 2 hours after baby finishes. After that, throw it away. | ||
The rule of 4s
Many parents remember the first two numbers as the rule of 4s: 4 hours on the counter, 4 days in the fridge. It is a handy memory trick rather than an official CDC term, but it matches the CDC times for freshly pumped milk. The freezer is the exception, so it helps to write the date on every bag.
How long is thawed breast milk good for?
If you thaw breast milk in the refrigerator, use it within 24 hours. The CDC is specific about when that clock starts: count the 24 hours from the moment the milk is completely thawed, not from when you took it out of the freezer.
Once thawed milk is brought to room temperature or warmed, use it within 2 hours.
Can you refreeze thawed breast milk?
No. The CDC says to never refreeze breast milk after it has thawed.
How to thaw breast milk safely
- In the refrigerator overnight.
- In a bowl of warm or lukewarm water.
- Under lukewarm running water.
Never thaw or heat breast milk in a microwave. The CDC notes that microwaving can destroy nutrients in breast milk.
What about the milk left in the bottle?
If your baby did not finish the bottle, use the leftover milk within 2 hours. After 2 hours, the CDC says leftover breast milk should be thrown away.
Freezer times: CDC vs AAP
The American Academy of Pediatrics gives slightly different freezer times depending on the freezer: up to 9 months in a refrigerator freezer with its own door (0°F), and up to 12 months in a chest or deep freezer (−4°F). Both agree on 4 hours at room temperature and 4 days in the fridge. If you are unsure, the shorter time is the safe one.
Common questions
How long can breast milk sit out?
Freshly pumped breast milk can sit out for up to 4 hours at 77°F or colder, according to the CDC. Milk your baby has already started, and thawed milk once it is warmed or at room temperature, get 2 hours.
How long can thawed milk sit out?
Once it is at room temperature or warmed, use it within 2 hours.
Sources
- CDC, Breast Milk Storage and Preparation: cdc.gov
- American Academy of Pediatrics, Storing and Preparing Expressed Breast Milk: healthychildren.org
Written by the FeedEase team. Every number on this page is checked against the sources above. This is general information, not medical advice: every baby is different, so check with your pediatrician.
