Milk & formula storage · Formula storage
How long is formula good for?
Last reviewed November 2026 against AAP, CDC, NHS and WHO guidance · Sources
Quick answer
The CDC says to use mixed formula within 2 hours of preparing it and within 1 hour once your baby starts feeding, then throw out what's left. Refrigerated formula should be used within 24 hours. Most opened powder containers must be used within 1 month, so check the label.
- Mixed, not started
- 2 hours
- Once feeding starts
- 1 hour
- In the fridge
- 24 hours
On this page
How long does formula last?
Formula has tighter limits than breast milk because powdered formula isn't sterile, and once your baby drinks from the bottle, saliva lets bacteria grow faster.
| Situation | How long | Then |
|---|---|---|
| Mixed formula, feeding not started | Within 2 hours of mixing | If you won't start within 2 hours, put it straight in the fridge |
| Once your baby starts drinking | Within 1 hour | Throw out anything left in the bottle |
| Mixed formula in the fridge | Within 24 hours | Throw it out if you can't remember when you made it |
| Opened powder container | Most within 1 month (check the label) | Store cool and dry with the lid closed, not in the fridge |
| Ready-to-feed or liquid concentrate, opened | Follow the label | CDC's preparation page gives no time limit |
Does my baby need extra precautions?
Yes, if your baby is under 2 months, was born premature (before 37 weeks) or has a weakened immune system. Powdered formula can carry Cronobacter germs, and the CDC advises extra steps for these babies:
- Consider liquid ready-to-feed formula when possible, which is made to be sterile.
- For powder, boil the water, then let it cool for no longer than about 5 minutes. Very hot water, around 158°F (70°C), is needed to kill the germs.
- Add the exact amount of powder while the water is still hot, then cool the bottle to body temperature and test it on your wrist: warm, not hot.
Does formula need to be warmed?
No. The CDC says formula doesn't need to be warmed. If your baby prefers it warm, hold the bottle under warm running water and test a few drops on your wrist. Never use a microwave, which creates hot spots that can burn your baby's mouth.
How do I keep track of the clock at 3am?
Storage rules all start from a time: when you pumped, when it thawed, when you mixed it, when the feed began. Those are exactly the times tired parents forget, especially when someone else made the bottle.
- Label every container of expressed milk with the date (and time, if you'll use it within days).
- Write the mixing time on a formula bottle you've put in the fridge, or tape a note to the fridge.
- Note when each feed starts. That's the clock for the 1-hour formula rule and the 2-hour leftover milk rule.
Feedoo Baby logs the time of every feed and who gave it, so whoever takes the next shift can see when the last bottle started. See how to track baby feeding for a simple routine.
When to call your pediatrician
- A rectal temperature of 100.4°F (38°C) or higher in a baby 3 months or younger. The AAP says to call right away, even if your baby seems otherwise well.
- Fewer wet diapers than expected for their age (fewer than 6 a day from about day 5), or dark yellow urine.
- Very sleepy and hard to wake for feeds, floppy, or unusually quiet.
- Refusing feeds, or feeding poorly several times in a row.
- Signs of dehydration: dry mouth, no tears, or a sunken soft spot on the head.
- Forceful or green vomiting, or vomiting after most feeds.
- Red, black (after the first meconium poops) or white/pale gray poop.
- Yellow skin or eyes that spread or deepen, or any yellow color in the first 24 hours.
- Trouble breathing, blue or gray lips, or your baby is limp or very hard to wake: call 911 (or your local emergency number) now.
If something feels wrong, trust that feeling and call. You never need a reason beyond worry.
Questions parents ask
How long is formula good for after mixing?
Use it within 2 hours of mixing, according to the CDC. If you won't start the feed within 2 hours, put the bottle in the fridge right away and use it within 24 hours.
Can I freeze formula?
The CDC's formula preparation page doesn't give freezer guidance. Follow the instructions on your formula's label, and don't freeze it unless the label says you can.
Can I use formula past its expiration date?
No. The CDC says never to use formula after the Use By date on the container, and to check that the container has no dents, puffy ends or rust spots.
Is breast milk storage the same as formula?
No. Breast milk keeps longer: up to 4 hours at room temperature and 4 days in the fridge. See the breast milk storage guidelines.
Related guides
- How long can formula sit out?Mixed formula can sit out up to 2 hours before feeding, and 1 hour once your baby starts drinking. Then throw out leftovers. CDC rules and why.
- How long is formula good in the fridge?Mixed formula is good for 24 hours in the fridge, per the CDC. Refrigerate right away if you won't feed within 2 hours, and never save leftovers.
- How long is formula good after opening?Most opened powdered formula must be used within 1 month, per the CDC. Store it cool and dry, not in the fridge. What to do with ready-to-feed.
- Breast milk storage guidelines: room temperature, fridge and freezerHow long breast milk lasts: 4 hours at room temperature, 4 days in the fridge, 6 to 12 months in the freezer, plus thawed milk and leftover rules from the CDC.
- How to track baby feeding and diapersWhy pediatricians ask about feeds and diapers, exactly what to log for breast, bottle and combo feeding, and paper vs notes app vs tracking app compared.
Free tools
Sources
Last reviewed November 2026. Numbers are ranges from these public health sources; 1 oz ≈ 30 ml.
Feedoo Baby shares general information, not medical advice. Every baby is different. If you're worried about feeding, weight gain, diapers or your baby's health, call your pediatrician, midwife or health visitor.