Best Breast Milk Freezer Storage Tips

This post does not contain affiliate links. It is designed for full-term, healthy babies. If your baby is premature or unwell please contact your healthcare provider for advice as they may require stricter storage guidelines. 

When you first start pumping it can all seem a bit overwhelming.

First, you need to choose a breast pump, a sterilizing method, a bottle.

Then once you’ve figured out all that, and how to actually do it, you need to safely store the stuff before giving it to your baby. 

Don’t worry, this guide has you covered!

I’ll show you the best way to keep your extra milk and make the most of your storage space.

How Long Can I Store Breast Milk?

It is likely at some point you will want to store your breast milk.

Whether this is to be given while you are not with your baby, or overnight so your partner can help with night feeds.

But how long can you actually keep milk for?

The fresher you can give your milk the better.

Breast milk contains proteins and nutrients specific to your baby’s current needs.

Because of this, it’s a good idea to use your oldest milk first to keep your stash as fresh as possible.

Over time some of the antibodies and nutrients found in milk will degrade, and freezing causes additional damage as well.

Unfortunately, formula milk does not contain any maternal antibodies, so frozen breastmilk is still worth giving. 

There is no consensus on the exact amount of time breast milk can be kept and you will find small differences with each source you use.

I use the rule of 6 as its for me to remember

  • 6 hours at room temperature 
    • Breast milk stored at room temperature should still be kept as cool as possible.
    • If the room is very warm or the milk is in direct sunlight it will not keep 6 hours
  • 6 days in the fridge 
    • Breast milk stored in the fridge should be kept in the main body of the fridge and not in the door as the door temperature can be variable.
    • Milk should be kept on a higher shelf than meat or dairy to prevent accidental contamination
  • 6 months in the freezer.
    • Make sure your freezer stash is kept at a consistent temperature.
    • Achieve this by keeping your milk in the center of the freezer so it is less affected by you opening the freezer.

How Much Breast Milk Should I Store?

It is important not to refreeze stored breast milk. Once defrosted it should be used within 24 hours.

To avoid wasting precious milk it is advisable to store small amounts. You can always defrost more stored milk if needed.

If you are just starting I would recommend storing in 2 ounce (60ml) and 1 ounce (30ml) batches.

This way you can use 2 ounces (60ml) as your main feed and top-up in 1 ounce (30ml) increments until your baby is no longer hungry

Once you know how much milk your baby takes on an average feed you can start storing batches in this size.

How Should I Label My Breast Milk?

Breast milk should be clearly labeled so you can easily prioritize using up the older milk first.

Whichever storage method you use you will want to include the following information:

  • The date the milk was pumped
  • How much breast milk is in the container
  • Your baby’s name (If the milk will be used in a childcare setting)

Use waterproof labels and ink for labeling as condensation in the freezer could cause some markers to rub off.

What Should I Store My Breast Milk In?

You must store breastmilk in a sealed container. Clean it well first and if your baby is under a year old sterilize it before using it to store milk.

If you use plastic bags or plastic containers make sure they are designed to hold warm breast milk.

Do not be tempted to use a ziplock bag or ordinary freezer bag as they will likely contain the harmful chemical bisphenol A which can leach into the milk.

1) Breast Milk Storage Bags

Breast milk storage bags are an easy way to store frozen milk as they take up so little freezer space.

Some will even let you pump directly into the bag which can be convenient if your pumping session is on the go or at work. 

Breast milk bags will stack up like ice packs if you initially freeze each bag on something flat like a cookie sheet first.

They are a great storage solution as they don’t take up much space, but I really try and limit my use of single-use plastic and couldn’t justify breastmilk bags purely for my convenience. 

2) Breast Milk Storage Containers

Usually, these milk containers are plastic bottles. Their advantage over milk bags however is they can be used again and again.

You may be able to use baby bottles to freeze breastmilk.

I don’t advise this because a bottle of milk is quite bulky to store and it means you will need lots of bottles which are often expensive.

Purpose-designed storage containers come in a range of sizes and are much more efficient for storage.

Make sure you don’t fill above the recommended guide or they may become damaged as the milk freezes and expands.

How Do I Reheat Frozen Breast Milk?

Breast milk should be gently reheated.

If you know you will need it in advance my favorite method is to take it out of the freezer the night before and pop it in the fridge. 

Check in the morning, it may still be a little icy but a few hours on the kitchen counter is usually sufficient.

You can speed this process up by placing the milk into a bowl of warm water or running it under a tap

You should not use boiling water or a microwave to reheat breast milk. This is for two reasons

1) You may accidentally create hot spots within the milk bottle that could burn your baby’s mouth.

2) You may destroy some of the important proteins within breastmilk

What Should I Do With Extra Breast Milk?

If you are lucky enough to have a surplus of breast milk you may want some creative ideas to make sure none goes to waste. My favorite options are:

  • Frozen breast milk ice lollies or milk cubes
    • These are a great idea for keeping your baby cool in the summer months. If you’re feeling really adventurous you could even make ice cream!
  • Donate to a human milk bank
    • Help a mom and baby in need and see if there is a donor bank in your area. 
  • Use in a baby bath
    • Breast milk is great for the skin and adding some to a baby bath can really help with dry areas or a nappy rash.
  • Use to soothe sore nipples
    • Similar to above, breastmilk will aid in soothing sore nipples.


How Long Can I Keep Breastmilk If My Baby Does Not Finish Their Bottle?

It can feel painful to throw away any of that liquid gold, but if your baby doesn’t finish their bottle it can only be kept for 2 hours in the fridge before it should be discarded.

This is because bacteria from your baby’s mouth may have contaminated the remaining milk

Why Does My Milk Smell Soapy?

If you have high levels of fat (lipase) in your milk it will have a soapy, maybe even sour, smell when defrosted.

This is not harmful and many babies will still happily drink the milk.

If your little one is refusing defrosted milk click here to learn how to deactivate lipase

How Do I Tell If My Milk Has Gone Off?

If your milk smells rancid then it has gone off, however, sniff testing alone can be inaccurate due to lipase levels.

Breast milk will naturally separate when left standing. It should mix together easily when swirled if there are still chunks present then it is most likely off.

You can also taste test to ensure that your milk is not off.

Remember: If in doubt, chuck it out!