How long can i keep formula milk in the fridge

If you’re prepping formula bottles for your infant, you need to know how long they’ll last in the fridge or on the counter. Read on for important formula tips for the safest bottle-feeding experience.

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In This Article

• How long is a bottle of formula good for?
• How long does formula last?
• Safety tips when preparing and storing baby formula

You’d think that when it comes to feeding your baby a bottle of formula, the process would be pretty straightforward. But while babies tend to grab that nipple and swallow quite easily, getting to that point calls for extreme care. Washing bottles and nipples, mixing formula from powder or concentrate, and then storing your creations means following safety protocols — every single time.

To help you get it right, we’ve put together this primer to explain how long formula is good for, whether you can leave it on the counter or in the fridge, and what you need to know when you open up a can or container. Here’s to a safe and happy formula-feeding experience!

How long is a bottle of formula good for?

Some of the most common questions about bottle-feeding revolve around how long formula lasts. Once you’ve made a bottle for your baby, here are the details for each scenario: 

If you leave a formula bottle out at room temperature for too long, it can go bad, so always use it within two hours of making it. This is the case for all formula bottles you prep, whether they’re made from powder, a concentrate, or you’ve opened a ready-to-feed jar or single-serving baby bottle. 

But if your baby has already begun to drink from the bottle, it should be used within one hour from when she started.

In the fridge

As for how long prepared formula can stay in the fridge, whether it’s made from powder or concentrate, keep in mind that it must be refrigerated as soon as the bottle is made and then served within 24 hours. 

If your baby started to drink from one of those bottles but didn’t finish it, it has to be discarded within an hour, so don’t be tempted to refrigerate it and then offer it again at the next feeding. 

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Getting ready for the sitter or leaving for work? You can make several bottles in the morning if you’d like, but each one must be consumed (or tossed) within 24 hours. 

It’s a good idea to label each bottle of formula with the date so you remember when it was made. Not sure if a bottle is safe? Toss it out.

Can you reheat a bottle of formula?

You don’t have to warm up a bottle of formula (room temperature or even cold from the fridge is just fine). But if you do heat it gently, once you’ve warmed it, rewarming it isn’t recommended, as bacteria thrive in warm places. And when it comes to serving a warmed-up bottle, do so within one hour. 

Do you have to throw out leftover formula?

While this can be hard to do, especially if you’re running low on formula at home or you can’t find the usual brand your baby drinks, you can’t save that leftover ounce or two at the end of a feeding. 

The reason? When formula and infant saliva mix, bacteria can start to grow inside the bottle, which means refrigerating it, reheating it or saving it on the counter for later are all no-go’s. To be safe, discard it.

How long does formula last?

When it comes to larger cans and bottles of formula, it’s important to read the labels carefully when you’re ready to open, serve and store it. Here’s more about how long formula lasts: 

Does formula go bad? 

Before you open any formula type (powder, concentrate, or ready-to-serve) check that it’s not expired, recalled or damaged in any way (dented, leaking, rusty). 

Expiration dates are usually stamped on the top or bottom of the can or on the side of the label on ready-to-serve. Unopened containers of any type of infant formula should be stored inside the house in a cool, dry spot and used before the expiration date.

Once opened, how long does baby formula last? 

In general, once you’ve opened a container of powdered formula it should be used up within 30 days. When you first open the container, write the date on the lid so you remember, the Centers for Disease Control and Prevention (CDC) advises. 

Store powder tightly sealed at room temperature in a cool, dry spot in the house. Opened cans or bottles of concentrate or ready-to-serve formulas can be refrigerated for up to 48 hours.

Can you freeze formula? 

Freezing formula, no matter the type, isn’t recommended, as it may cause the mixture to separate and could compromise the safety of the formula. 

In order to avoid wasting formula, it’s best to mix and offer small bottles that your baby can finish in the allotted time and if she’s still hungry, mix up a little more. 

Safety tips when preparing and storing baby formula

After you’ve checked that the formula type you’ve purchased hasn’t expired and is in good shape, follow these safety tips when preparing and storing infant formula:

• Start off clean. As with anything you do in the kitchen, always wash your hands and the surfaces you’re working on as well as your bottles and nipples with soap and water. You should also wash the lids of cans you’re using and the measuring scoop inside.

• Mix with care. When making formula bottles, always put the water in first and then add the powder. But don’t add water to ready-to-feed formulas or dilute any bottles in order to stretch a feeding. Too much water reduces the nutrients your baby gets, and extra water messes up the electrolyte and nutritional content of formula — two dangerous scenarios.

• Store it right. Prepared room temperature formula can stay out for two hours, but if you’ve started to serve it to your baby, it has to be used within one hour. Bottles not given to your infant should be stored ASAP in the fridge and are good for 24 hours. With ready-to-use formula, cover and refrigerate any unused portion from a new container but discard it after more than 48 hours.

• Never DIY. Even if you’re faced with a shortage or can’t find the brand you’re used to, never make your own formula. These concoctions won’t contain the proper balance of vitamins and minerals, and they may introduce foodborne illnesses due to contamination. 

• Skip the microwave. A microwave tends to heat unevenly, which can create hot spots in a baby’s bottle and potentially burn her mouth and throat. Instead, if you want to warm a bottle, do so gently in running warm water, in a pan of warmed water that’s off the heat source, or in a countertop bottle warmer. 

• Test the bottle. Be sure to test the temperature of the milk against the inside of your wrist (a super sensitive spot of skin) to make sure it’s lukewarm only, never hot.

• Discard leftovers. Don’t be tempted to offer the last little bit of formula in the bottle to your baby at the next feeding (or the next day). Always follow the guidelines above when making and storing prepared formula bottles so your baby has a fresh serving each time.

• Avoid using machines that mix or make formula for you. These have not been found to be reliable.

From the What to Expect editorial team and Heidi Murkoff, author of What to Expect When You're Expecting. What to Expect follows strict reporting guidelines and uses only credible sources, such as peer-reviewed studies, academic research institutions and highly respected health organizations. Learn how we keep our content accurate and up-to-date by reading our medical review and editorial policy.