Not sure how to freeze breast milk? Here’s everything you need to know about how to safely freeze breast milk, as well as how to organize your milk and optimize the space in your freezer.
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When my son was about six months old, my husband came home from the grocery store and was putting the food away. When he opened the freezer door, he said, “Where am I supposed to put OUR food?? The entire freezer is full of the baby’s food.”
He was right – there were breast milk bags on every shelf, and there was very little space left for essentials like Ben & Jerry’s and frozen pizza.
Plus, all of the breast milk was extremely disorganized. Whenever I wanted to rotate out an older bag of milk, it took me forever to find the oldest bag to defrost.
Eventually, I learned the best ways to freeze your breast milk so that it’s organized and takes up as little space as possible. Here’s what you need to know!
How to Freeze Breast Milk
In most cases, if you want to conserve space, you’ll want to freeze your breast milk in breast milk storage bags.
(Which kind of breast milk bags should you use? Some factors to consider are whether you want to pump directly into the bags, the size of the bags, whether you want to use disposable or reusable, and cost. You can read reviews of different brands here.)
1. Transfer your milk
First, transfer your milk from the bottle you pumped it in to the breast milk bag.
When you are pouring breast milk from a bottle to a bag, you may want to use your flange as a funnel to avoid spills.
2. Label the bag
Before you put the breast milk bag in the freezer, label it with the date, the quantity of breast milk in the bag (in oz or ml), and the name of your child (if there is a chance the bag will be used in a childcare setting).
(You can also add the pump time if you’d like, but this is less important.)
Some people also write any illness or symptoms that baby is experiencing, with the thought that this breast milk might be useful in the future when baby has the same symptoms.
3. Freeze flat
When you put the breast milk in the freezer, lay it flat to freeze.
This is the most important thing that you can do to maximize the amount of milk that you can fit in your freezer, because you can stack it more compactly when it’s frozen flat.
Some people lay their milk out on a cookie sheet to freeze. A takeout container or large Tupperware will also work.
4. Store frozen breast milk in bricks
Once the milk is frozen flat, you can “brick” it – which just means that it’s stored in a row with other frozen flat bags.
Frozen milk can be stored for up to a year.
How to Organize Breast Milk in Freezer
Once you have your breast milk frozen flat like a brick, how do you store the bags in your freezer to maximize space?
One trick to fitting more breast milk bricks into each container is to stack them up/down/up/down. Most breast milk bags tend to have a bit more milk frozen in the bottom of the bag, so alternating which side is down allows you to fit more in.
What container should you stack your frozen breast milk bricks in? Here are a few good options.
1. Store in zip-top gallon-sized plastic bags
You can bag them up in large plastic bags for storing in the freezer.
Make sure to store the bags so that they are clearly labeled and it’s easy to find the oldest milk.
2. Reuse boxes
Boxes for 12 cans of soda can also work well. Put the newest milk in the back, and the oldest in front.
3. Use a plastic or glass container
What if You Run out of Room in Your Freezer?
If you still end up running out of room for ice cream in your freezer, like I did, you have a few options. One is to borrow freezer space in a family member or friend’s freezer, if you have anyone nearby who’s willing to lend you some space.
Another is to donate your extra milk. You can do this by donating to a milk bank or via informal milk sharing.
Finally, you can buy a deep freezer to store more milk. (This is what we ended up doing.)
Lots of people in our Facebook group have found creative ways to make a deep freezer work, even when living in a small apartment.
For example, since they aren’t opened frequently, one way to find space is to make the freezer dual-purpose, such as using it as a nightstand or end table. Others fit their deep freezer in a closet.
This medium-sized deep freezer is perfect for a smaller space and has 2.1 cubic feet of storage:
This larger deep freezer will work great in a home with the extra space for it:
How to Track How Much Breast Milk Is In Your Freezer
Lots of people like to keep track of how much breast milk they have stocked up. Here are some easy ways to track your freezer stash.
1. A Pumping App
Pumping apps like Milk Maid or Pump Log can track how much breast milk you have frozen at any given time. The advantage of this method is that you can easily update your total whenever you add or remove milk, and it does all of the math for you.
Most apps that calculate total stash do cost a few dollars. You can read reviews of a few different options here.
2. Spreadsheet
A spreadsheet is another great option for tracking bags of breast milk, and it allows you total control over how you track it. Here is an example of how you can do this using Google Sheets.
3. Whiteboard
You can put a magnetic whiteboard on the outside of your freezer and update the total number of ounces (or breast milk bags, whichever you prefer to track) every time you add or remove milk.
4. Write on the Outside
Once you fill up a zip-top bag, box, or storage bin, write the total number of oz/ml on the outside so that you can do some quick math when you open up the freezer.
Here’s a free printable that you can use to label your milk containers! Just stick it inside the zip-top bag or tape it to the outside of your box/bin.
Hopefully these tips help you with how to freeze your breast milk! Let us know in the comments if you have any other tips, and don’t forget to download your free printable for labeling your milk!
Comments & Chitchat
Amy Chang says
What volumes of breastmilk are most ideal to freeze in each bag?
Amanda Glenn, CLC says
Hi Amy! You kind of have to figure it out with trial and error – there’s no one perfect amount. A lot of people do whatever feeding size baby is eating right now, some people do small amounts because it’s easier not to waste any, oversuppliers might do larger amounts in order to use fewer bags.
If you don’t use all of the milk in a bag and you thawed it cold, you can save it in the fridge for later within 24 hours. Hope that helps!
Alexa says
This may be a very silly question but I had my bags laying on top of ice cube trays with milk in them (to use in baths, etc). When I went to grab one recently they were all moldy (I think it was mold?). Is the frozen breast milk that was on top still ok?
Amanda Glenn, CLC says
Hi Alexa! Assuming the inside of the milk bag didn’t touch the mold – which it sounds like it didn’t – it should be okay? Ask your pediatrician if you’re worried but I don’t necessarily see an issue. 🙂
Daisy says
Should I throw away my frozen milk if it has air bubbles
Amanda Glenn, CLC says
No need!
Christine says
Does it matter if i buy a manual defrost or auto defrost freezer? Thank you.
Amanda Glenn, CLC says
Hi Christine, I’ve never read any guidelines or anything that differentiate, so I don’t think it matters! 🙂
Kate says
Amanda, do you know how much milk each freezer size will hold? I’ve seen estimates for a 5.1 cu ft freezer holding anywhere from 1,500 to 2,500 oz. I’d like to feed my baby breastmilk for the full year but would ideally like to stop pumping once I have enough of a stash (~3 months) to last the remainder of the year.
Amanda Glenn says
This is a great question but I don’t know! I didn’t count when I had mine frozen and I would imagine it varies a bit based on how you freeze it and stack it. So sorry I can’t answer this!
Katie says
I think I’m going to need to invest in a chest freezer, but I’m trying to decide what size. I really don’t want something huge. My baby is 1 month old and I plan to feed her breast milk until she’s 6 months. She’ll start daycare in November, so until then there won’t be much taken out of the freezer, if any. I add roughly 4 bags of milk to the freezer per day, currently.
Amanda Glenn says
Hi Katie! Maybe you could fill up a smaller one and donate any extra, after that? If you want to keep everything you pump (like to wean early) I would probably get the bigger one.
(I would try using some frozen milk now to make sure you don’t have a lipase issue!)