Breast Milk Storage Guidelines
Medically reviewed by Safi Ullah Khan
Medically reviewed by Safi Ullah Khan · Written by Muneeb Rana · Last updated 21 October 2026
Quick answer: Breast milk storage, per the AAP: freshly expressed milk is best used within 4 hours at room temperature and 4 days in the fridge (the rule of 4s). It keeps up to 9 months in a freezer with a separate door and up to 12 months in a deep freezer. Use thawed milk within 24 hours and never microwave it.
TL;DR
- Room temperature: up to 4 hours.
- Fridge: up to 4 days. Freezer: 9-12 months.
- Thawed milk: use within 24 hours; don't refreeze.
Breast milk storage rules can feel confusing because different organisations round numbers differently. Here's the AAP's guidance at a glance, with the conservative rule of 4s.
Breast milk storage chart
| Where | Temperature | How long |
|---|---|---|
| Countertop | Up to 77°F (25°C) | Up to 4 hours |
| Fridge | 39°F (4°C) or colder | Up to 4 days |
| Freezer (separate door) | 0°F (−18°C) | Up to 9 months |
| Deep freezer | −4°F (−20°C) | Up to 12 months |
| Thawed, in fridge | 39°F (4°C) | Best within 24 hours |
| Leftover after a feed | Room temperature | Within 2 hours |
Source: AAP HealthyChildren. Hospitals may have stricter rules for premature or hospitalised babies.
How to store
- Use clean containers or breast milk bags
- Label with the date (and time if you pump often)
- Store at the back of the fridge or freezer, not in the door
- Leave room at the top: milk expands when frozen
- Freeze in small portions, 2-4 oz, to reduce waste
Thawing and warming
Thaw in the fridge overnight, under warm running water, or in a bowl of warm water. Never microwave breast milk: it heats unevenly. Swirl to mix the fat back in. Once thawed, keep it in the fridge and use it within 24 hours.
Use oldest first
Rotate your stash so the oldest milk is used first. A pumping log helps you know what you have.
Logging bottles
When someone else gives a bottle, logging it in Tot records the time and amount so you can plan your next pumping session.
Related: pumping schedule · how much breast milk in a bottle · pumping log · baby feeding tracker · baby feeding chart by month · newborn feeding guide
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Sources
- AAP HealthyChildren.org: Tips for Freezing and Refrigerating Breast Milk: www.healthychildren.org (accessed 21 October 2026)
- La Leche League International: Storing Human Milk: llli.org (accessed 21 October 2026)
- NHS: Expressing breast milk: www.nhs.uk (accessed 21 October 2026)
Medical disclaimer:
Tot and this website give general information only. Feeding, sleep and growth ranges vary; always follow your pediatrician's advice. If your baby is unwell, contact your doctor or emergency services.
FAQ
How long can breast milk sit out?
Up to 4 hours at room temperature is best, according to the AAP.
How long does breast milk last in the fridge?
Up to 4 days at 39°F (4°C) or colder.
Can I refreeze thawed breast milk?
No. Use thawed milk within 24 hours.
Can I microwave breast milk?
No. The AAP says microwaving isn't safe because it heats unevenly.
Can I reuse leftover breast milk?
Use it within 2 hours after your baby finishes, then discard.
Related guides
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