How Long Is Formula Good For? After Mixing, At Room Temp, More

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How Long Is Formula Good Once Mixed? And Other Questions About Formula

Medically reviewed by Karen Gill, M.D. — Written by The Healthline Editorial Team on December 19, 2019

Room temperature
Refrigerated
Partially used
Warmed up
Opened unmixed
Unopened unmixed
Takeaway

The amount of time baby formula stays good once mixed depends on several factors, such as the brand, whether it’s mixed and already heated, and the temperature it’s stored.

Mother wearing baby and shopping in formula aisle

There comes a time in all new parents’ lives when you’re so tired that you’re operating on automatic. You feed your newborn a bottle and they fall asleep in their bedside bassinet mid-meal. You groggily put the bottle down and fall asleep yourself — for what feels like 5 minutes.

Now baby’s woken up hungry again and you’re wondering if you can just pick up where you left off. But you look at the clock — and instead of 5 minutes, it’s been 65. Is that half-eaten bottle of formula a foot away still good?

This is just one scenario where a formula question might come to mind, but there are lots of others — so if formula rules have you scratching your head, you’re not alone. Let’s get you some answers, STAT.

Check the package instructions

We’ll give you some general guidelines, but always check your specific formula’s packaging for mixing, storing, and use instructions. There can be slight variations among brands — and even within brands!

Once you prepare formula from powder, how long does it stay good at room temperature?

Once you mix water and formula powder to create that magical elixir that nourishes your sweet babe, the countdown clock starts ticking. As a general rule, the bottle will last for 2 hours at room temperature, untouched and unheated.

But check the label instructions — for some brands, manufacturer instructions say a bottle is only considered safe for 1 hour at room temperature once mixed. It may depend on whether the brand is following American Academy of Pediatrics or Centers for Disease Control and Prevention guidelines.

Related: 13 of the best baby formulas

Does it last longer refrigerated?

Yes, as long as your baby doesn’t drink from the bottle.

An unused bottle of formula mixed from powder can last up to 24 hours in the fridge. That’s why many parents opt to make a larger batch of formula in the morning and portion out into bottles — or pour into bottles as needed — for use throughout the day.

These parents know that a crying baby is often a hungry-right-now baby who doesn’t want to wait for you to mix a bottle.

Your fridge temp should be 40°F (4.4°C) or lower.

As an aside, it’s not recommended that you freeze formula. It can change the texture and doesn’t extend the period of time during which the formula is still good. If you’re new to formula after breastfeeding, it’s important to know the guidelines are different in this and other regards.

Related: How long can breast milk sit out?

Does a partially used bottle last as long in the refrigerator as a freshly mixed one?

No. In fact, if your little one has had some of a bottle but doesn’t want the rest, you should dump it within an hour. Don’t put it in the fridge for later use.

Milk-based products are notorious for growing bacteria. Once your baby has drunk from a bottle, bacteria is introduced and the formula shouldn’t be saved. (Incidentally, this is also why you shouldn’t drink directly from the milk carton, even if it’s just a swig after that chocolate chip cookie.)

If you’ve heated up a bottle, can you store the unused portion in fridge and use again later?

Nope. Again, bacteria is the issue here — and bacteria thrive even more once given a nice warm environment to grow in.

Something else to know: If you’ve warmed up a bottle, our previous 2-hour guideline for untouched formula doesn’t apply. A heated bottle should be used within 1 hour, and any remaining should be poured down the sink after that time. This applies to formulas prepared from powder as well as concentrates and ready-to-drink options.

How long does unmixed formula last once the container is opened?

Generally, you should use up powdered formula within a month of opening the container. We found this to be the guideline on labels for popular brands like Similac and Enfamil as well as organic alternatives from Happy Baby Organics and Earth’s Best. This shouldn’t be a problem, given your little one’s voracious appetite!

Related: 10 organic formula options worth trying (and where to buy them)

How long does unopened, unmixed formula last?

Fortunately, you don’t have to guess at this one or remember the day you bought the formula. A sealed container of formula, whether powder, concentrate, or ready-to-drink, will always have an expiration date on it. In most cases, you’ll find this printed on the bottom.

The powdered formulas we looked at in our local store had dates more than a year away. So if you find yourself with unopened containers after your baby transitions off formula, at least you’ll be prepared for any upcoming zombie apocalypse.

Store sealed containers in a cool, dry place and avoid exposure to extreme temperatures.

The takeaway

All the rules surrounding formula can seem a little nitpicky, but remember it’s your baby’s delicate tummy you’re dealing with and the guidelines suddenly become incredibly doable. And you’ll get the hang of how much your baby eats pretty quickly, decreasing or even eliminating the amount of formula that ends up down the drain.

“When in doubt, dump it out” is a good rule of thumb here. But like all things baby, you’ve got this and will soon be running on automatic — though we can’t promise you’ll never doze off after preparing a bottle!

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How we reviewed this article:

SourcesHistoryHealthline has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical journals and associations. We only use quality, credible sources to ensure content accuracy and integrity. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.

Formula feeding FAQs: Preparation and storage. (2015). https://kidshealth.org/en/parents/formulafeed-storing.html
Infant formula preparation and storage. (2018).https://www.cdc.gov/nutrition/infantandtoddlernutrition/formula-feeding/infant-formula-preparation-and-storage.html
Pastore R. (2010). Are you preparing your baby’s bottles correctly?https://publications.aap.org/aapnews/article/31/10/37/9030/Are-you-preparing-your-baby-s-bottles-correctly

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Medically reviewed by Karen Gill, M.D. — Written by The Healthline Editorial Team on December 19, 2019

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