How to Store Breast Milk

Storing breast milk properly helps keep all that hard work safe and nutritious for your baby. Whether you’re heading back into the office, building a stash for convenience, or navigating the newborn stage, knowing how to store breast milk can reduce stress and waste. With just a few simple guidelines, you can ensure that your milk stays fresh and ready whenever your baby needs it.

Key Takeaways

Label and date all stored milk to track freshness.
Use appropriate containers designed for breast milk storage.
Thaw and use milk safely, avoiding refreezing or reheating multiple times.

Breast Milk Storage Guidelines

The Centers for Disease Control and Prevention (CDC) offers clear recommendations on how long breast milk can be safely stored in different environments.

Room Temperature (77°F or colder)

At room temperature, freshly pumped breast milk can be safely stored for up to 4 hours. This is convenient if your baby will be feeding shortly after pumping or if you're in a setting without immediate access to a fridge. However, it’s still best to store or use the milk as soon as possible. If you’re traveling or spending time away from home, an insulated cooler with ice packs can help extend the window of freshness.

Refrigerator (40°F or colder)

In the refrigerator, breast milk can be stored for up to 4 days. For optimal storage, place containers at the back of the fridge rather than the door, as this helps maintain a more stable temperature. The fridge is ideal for milk you plan to use soon—like overnight, during the workweek, or when prepping bottles for daycare.

Freezer (0°F or colder)

Breast milk can be stored in the freezer for best quality up to 6 months, but is still considered safe for up to 12 months. Use freezer-safe storage bags or containers and leave room at the top for expansion. Laying bags flat can save space and allow for quicker thawing later on. Always thaw frozen milk in the refrigerator or under warm running water—never in the microwave.

Storing Breast Milk in the Fridge

How Long Can Breast Milk Last in the Fridge?

Freshly pumped breast milk can be kept in the refrigerator for up to 4 days. If you don’t plan to use it within that time, freeze it to preserve quality and nutrients.

Many working parents find it helpful to keep a small fridge stash at work or pump directly into bottles that go into a cooler bag and then into the fridge when they get home.

What Storage Containers Are Best for Fridge Storage?

Use BPA-free plastic bottles, breast milk storage bags, or glass containers with secure lids. Avoid reusing disposable bottle liners or standard food bags, as they may not be sterile or leak-proof.

Storing Breast Milk in the Freezer

How Long Can Breast Milk Last in the Freezer?

Milk stays freshest when used within 6 months but can remain safe for up to 12 months. Freezing is a great option for working parents or those creating a stash for nighttime feedings, travel, or emergencies.

You can freeze in larger amounts or small portions (1–2 oz) for flexibility during growth spurts, when baby may want smaller or more frequent feedings.

What Storage Containers Are Best for Freezer Storage?

Use breast milk storage bags designed for freezing or rigid containers that won’t crack in cold temps. Label each container with the date and amount for easy tracking.

Some parents find it helpful to freeze milk in ice cube trays (covered and sterilized), then transfer cubes to a storage bag. Each cube is about 1 oz—perfect for topping off bottles.

How Long Is Thawed Milk Good For?

In the fridge: Use within 24 hours
At room temperature: Use within 1–2 hours
Never refreeze previously thawed milk

How to Warm Up Breast Milk

Warm milk gently by placing the bottle or bag in a bowl of warm water or running warm water over it. Avoid microwaving—it can create uneven temperatures and damage the milk’s nutritional value.

Swirl gently to mix in any separated layers.

Can You Refrigerate Warmed Milk?

No. Once breast milk has been warmed, use it within 2 hours. Do not refrigerate or refreeze it again.

How to Tell if Breast Milk Is Bad

Signs of spoiled milk include:

Sour or soapy smell
Clumps or separation that doesn’t mix when swirled
Foul taste or strange color (note: slight color changes are usually okay)

Keep in mind that some frozen milk may smell a bit different due to lipase activity—it’s not always a sign it’s spoiled. If your baby refuses it, scalding before freezing may help in the future.

Breast Milk Storage Tips

Label all containers with the date and time of pumping
Freeze milk in small portions (2–4 oz) to reduce waste
Leave space at the top of containers for expansion when freezing
Use older milk first using the "first in, first out" rule
Clean hands and pump parts before each session
Transport milk safely with an insulated cooler and ice packs
Create a system—set reminders or use apps to track your inventory

Organization is key! A small dry-erase board or sticky note system on your fridge/freezer can help you stay on top of your milk supply at home.

Bottom Line

Proper storage of breast milk can help extend the benefits of breastfeeding even when you’re apart from your baby. With a little planning, you can build a reliable milk stash, avoid spoilage, and feel confident knowing your baby is getting safe, nutritious feedings.

If you're still learning the ropes or want more tips, try Birthly’s live, online breastfeeding class that covers everything from pumping at work to maximizing your freezer stash. Our expert instructors are here to answer your questions and help you find a routine that works for you.