Milk & formula storage · Opened formula
How long is formula good after opening?
Last reviewed November 2026 against AAP, CDC, NHS and WHO guidance · Sources
Quick answer
Most powdered infant formula needs to be used within 1 month of opening the container, according to the CDC, so check your label. Store it in a cool, dry place with the lid tightly closed, not in the fridge, and never use it after the Use By date. For opened ready-to-feed formula, follow the label.
- Opened powder
- Most within 1 month
- Store
- Cool, dry, lid closed
- In the fridge?
- No (powder)
On this page
How long does an opened can of formula powder last?
Most formulas need to be used within 1 month of opening, according to the CDC. Your label is the final word, since brands can differ. Write the date you opened it on the lid.
Never use formula after the Use By date, even if the container is unopened.
How should I store opened formula powder?
- In a cool, dry, indoor place with the lid tightly closed. Not in the fridge.
- Not in a car, garage or outdoors, where heat and damp can damage it.
- Keep the scoop in the container or a clean place, never on the counter or in the sink (CDC).
- Close the container as soon as you've measured the powder.
What about ready-to-feed and liquid concentrate?
The CDC's preparation page doesn't give a time limit for opened ready-to-feed or liquid concentrate, so follow the instructions on the label. Once it's in a bottle your baby has drunk from, the 1-hour rule applies, then throw out what's left. See how long formula can sit out.
All formula storage times
| 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 |
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
Can I use formula 2 months after opening?
Most formulas need to be used within 1 month of opening, according to the CDC. Check your label, and if it says 1 month, start a new container.
Should I refrigerate opened formula powder?
No. The CDC says to store opened powder in a cool, dry place with the lid tightly closed, and not in the fridge.
How can I tell if a container of formula is safe to use?
Check the Use By date and recall notices, and make sure the container has no dents, puffy ends or rust spots, as the CDC advises.
Related guides
- How long is formula good for?Mixed formula: use within 2 hours, 1 hour once feeding starts, 24 hours in the fridge. Opened powder: most within 1 month. Every CDC formula rule in one place.
- 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.
- 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.
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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.