Everything You Need to Know About How Long Can Breast Milk Sit Out

Published by 
Jess Miller
Last updated: 
March 29, 2023
mother is breastfeeding in the kitchen

In your determination to provide the best for your new baby, you’ve probably caught yourself asking: How long can breast milk sit out?

It’s important to know the answer because you could inadvertently feed your child bacteria-laden milk. When you know how long to keep breast milk out, you can keep your baby happy and healthy.

How Long Can Breast Milk Sit Out?

When answering the question, “How long can breast milk sit out?” there are several factors that you should consider. This includes the cleanliness of the environment, how much milk you express, and the temperature of the room when you express the milk.

However, there are some general guidelines to follow that will make sure you handle and store breast milk properly.

There’s a timeframe for how long you can keep breast milk at room temperature, as well as in the fridge and freezer. Each is different, and it’s important to know each one so you can keep your milk storage as healthy and nutritious as possible.

At room temperature

How long can breast milk sit out before being refrigerated? The CDC states that breast milk on a countertop at a room temperature of 77 degrees Fahrenheit or cooler can stay out for 4 hours.

Others will tell you that you can leave it out for six hours, but you should stick to the four-hour limit in almost every instance. It’s safer that way.

Keep in mind that this is only for freshly expressed breast milk. You have less time for breast milk that isn’t fresh.

If you’ve thawed frozen breast milk and left it out on the counter, you have one to two hours to use it. You also have two hours for leftover milk that your baby didn’t finish in their bottle. You should either refrigerate or use the milk before the allotted amount of time passes.

Doing so will keep the breast milk at its optimal quality and free of dangerous bacteria.


Once you move it to the fridge, how long does refrigerated breast milk last? If your fridge is set to 40 degrees Fahrenheit or colder, you can store breast milk there for up to 4 or 5 days.

Before then, you should use the milk or place it in the freezer. Ideally, you’ll place milk in the freezer by the third day. If you’ve placed frozen milk in the fridge to thaw, you have 24 hours to use it.

If you don’t have access to a fridge for a few hours, you can also store breast milk in an insulated cooler. With ice packs, you can keep milk in there for one day.

It’s also important to understand that the longer you store breast milk in the fridge, the more vitamin C you lose. If you want your child to ingest as much vitamin C as possible, you’ll use your breast milk as soon as possible.


If you set your freezer to 0 degrees Fahrenheit or colder, you can store breast milk for a much longer period of time. Instead of being limited to a few hours or days, you have an entire 12 months to use the milk.

Ideally, you won’t store breast milk in the freezer for longer than six months. Your baby is growing quickly, and your breast milk changes to accommodate their nutritional needs. Within six months, your baby has changed so much that the frozen milk likely won’t completely meet their needs.

If you previously pulled milk out of the freezer to thaw, do not ever refreeze it. This can promote both bacteria growth and break down essential nutrients in the milk. If your baby doesn’t finish the thawed milk, you can leave it out for up to 2 hours or refrigerate it for 24 hours.

How Should I Store Breast Milk?

Spectra Baby USA

Once you express or pump break milk, you should store the milk in the proper containers. You can use glass or BPA-free plastic containers, as well as plastic breast milk storage bags.

Kiinde Twist Pouch Breast Milk Storage Bags for Pumping

If you choose plastic bags, make sure they’re specifically meant for storing breast milk. Don’t use bottle liners or traditional household plastic bags.

Fill the bags or containers with milk and stop about an inch or two from the top. Breast milk will expand as it freezes, so this will prevent it from busting out.

Also, make sure you label every container of breast milk with the date you expressed it. This will help you remember how long you can keep the milk in the fridge or freezer. If you need to store milk at a childcare facility, write your baby’s name on the label too.

When placing the containers in the fridge or freezer, place them toward the back. This location stays cooler consistently, whereas door storage is susceptible to temperature fluctuations.

How Should I Thaw Frozen Breast Milk?

Kiinde Twist Pouch Breast Milk Storage Bags for Pumping, Freezing, and Feedin
Image source: amazon

These practices will help the milk warm up slowly and naturally. Don’t microwave frozen breast milk or heat it quickly on the stove. This can create hot pockets in the milk that can burn your baby’s mouth and potentially harm the milk’s antibodies.

Once the milk thaws completely, don’t put it back in the freezer. As previously stated, you can leave it at room temperature for 2 hours, or place it in the fridge for 24 hours.

How Long Can Breast Milk Sit Out? It Depends on the Situation

Breast Feeding
Image source: freepik

Failure to store breast milk properly can harm the nutrients it contains and allow bacteria to grow in the milk.

What are your experiences with learning how long breast milk can sit out? Let us know in the comments section.

Featured image source: freepik

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