Based on NHS guidance
How long does breast milk last? A UK storage guide
Pumped milk is precious. Here is how long expressed breast milk keeps in the fridge, freezer and cool bag, based on NHS guidance and in plain UK terms: millilitres and °C.
Breast milk storage times at a glance
| Where | How long | Good to know |
|---|---|---|
| Fridge at 4°C or colder | Up to 8 days | Keep it at the back of the fridge, not in the door. |
| Fridge warmer than 4°C, or you're not sure | Within 3 days | A cheap fridge thermometer tells you which applies. |
| Ice compartment of a fridge | Up to 2 weeks | |
| Freezer at -18°C or colder | Up to 6 months | Label and date every bag before freezing. |
| Cool bag with ice packs | Up to 24 hours | For milk that has already been cooled in the fridge. |
| Left in the bottle after a feed | Within 1 hour | Then throw away what's left. |
Safe storage and defrosting tips
- Sterilise your pump and containers before you use them.
- Label and date milk before it goes in the freezer, and use the oldest first.
- Defrost frozen milk slowly in the fridge, or faster in a jug of warm water.
- Once defrosted, gently shake it if it has separated and use it straight away.
- Never refreeze breast milk that has been defrosted.
- Never warm milk in a microwave or on the hob. It can cause hot spots that burn your baby's mouth.
Common questions
How long can breast milk stay in the fridge in the UK?
NHS guidance says up to 8 days at the back of a fridge at 4°C or colder. If your fridge is warmer than that, or you don't know its temperature, use the milk within 3 days.
How long does frozen breast milk last?
Up to 6 months in a freezer at -18°C or colder, or up to 2 weeks in the ice compartment of a fridge.
Can I refreeze breast milk once it has defrosted?
No. NHS guidance says not to refreeze breast milk that has been defrosted. Use it straight away.
How long is breast milk good for after a feed?
Use any milk left in the bottle within 1 hour, then throw the rest away.
How do I carry expressed breast milk to nursery or work?
Milk that has been cooled in the fridge can be carried in a cool bag with ice packs for up to 24 hours.
Can I warm breast milk in the microwave?
No. Warm it to body temperature in a jug of warm water instead. Microwaves and hobs can cause hot spots that burn your baby's mouth. Some babies are happy to drink it cold from the fridge.
Keep track without the guesswork
Little Stash is a pumping tracker made for UK mums. Log each session in millilitres, see every fridge and freezer bag by date, and get a gentle nudge before a bag reaches its NHS storage limit. One-off £9.99, no subscription.
Source: NHS: Expressing and storing breast milk, checked 16 October 2026. This guide is a summary, not medical advice. Little Stash is independent and not affiliated with or endorsed by the NHS. If you are worried about your baby's feeding, speak to your midwife, health visitor or GP.