How to Keep Breastmilk Frozen for 14+ Hours While Traveling

How to Keep Breastmilk Frozen for 14+ Hours While Traveling

During our most recent move, I had to figure out how to transport 400 ounces of pumped, frozen breastmilk.  After many hours of research, I found the most efficient, and cost-effective, way to transport milk via plane.  It wasn’t using dry ice.  It wasn’t shipping it via a next day service provider.

While researching, I kept reading about using dry ice.  Did you know that for the dry ice to effectively keep items frozen,  you have to pack one pound of dry ice for every pound of frozen breastmilk?  Well, 400 ounces is equal to 25 pounds.  So I would need 25 pounds of dry ice.  Meaning, my bag would probably be over 50 pounds.  I would be paying an extra fee for “heavy luggage,” or I would be lugging around a 50+ pound carry-on bag.  Dry ice is expensive too, typically $3 per pound.

While researching dry ice options, I called a local butcher where I could purchase dry ice.  He was the go-to guy for buying dry ice in our city, but he recommended NOT using dry ice.  He said that dry ice often changes the flavor of food, including breastmilk.  Many mothers had reported back to him that their baby would not take the frozen breastmilk after using dry ice to keep it frozen.  So using dry ice from the local butcher was out.  

The next option was to use a courier delivery service, similar to FedEx or UPS.  I would have to purchase specific boxes with dry ice compartments.  But, I already learned: Dry ice = bad!  I would have to pay for overnight shipping.  The largest box available cost $150 and would hold 200 ounces.  I also had to pay for overnight shipping, which cost $200.  Therefore, transporting 400 ounces would have cost me $700.  It would have been cheaper to buy my breastmilk a seat on the plane as we moved.

I am also a bit of a control freak, so the thought of dropping off breastmilk to be shipped and hoping it arrived at the next location was daunting.  I would also have to plan to ship the milk the day before we left for a house-hunting trip so we would be there when it arrived.  We already had a long to-do list when we landed in our new city, and the thought of trying to remember to pick up a couple of boxes of breastmilk was stressful.  And there was always the fear of, what if they lost my shipment?

So, after researching, I had to choose between transporting icky tasting breastmilk on my own or paying someone to ship breastmilk that would still use dry ice.  Neither option was good enough for me.  So, I came up with an even better option.  I knew we would be making one more home-searching trip before the final move.  My in-laws lived near our new town.  So, I was going to find a way to take milk with me.

Cooler full of frozen breastmilk

My husband and I went to a sporting goods store and bought the best cooler they had, as well as reusable ice blocks.  I was able to pack 200 ounces in the cooler, along with the ice packs.  Because I couldn’t fit 400 ounces in the cooler, I had to transport the breastmilk on two separate trips.  

On our first trip, I packed the cooler the night before we left for the airport and stored it in our freezer.  Twelve hours passed from the time we headed to the airport to the time we got to my in-laws’ home where I could pack the breastmilk in their deep freezer.  When we arrived at their house, the breastmilk was still frozen solid.  

The second trip was our final moving trip, and I could put the frozen breastmilk into our freezer right away.

Below are a couple of tricks you can use to ensure that your breastmilk stays frozen and travels safely on your plane ride.

Airplane landing during sunset

Tips for Transporting Breast Milk on a Flight

  1. When freezing your milk, lie it down flat in the freezer.  Use a plate or a pan to hold the bag flat.  Thin, flat bags of milk are much smaller.  You can get a lot more milk in a cooler when it is flat.
  2. Purchase a cooler that has a leakproof zipper and closed-cell rubber foam lining to ensure milk will stay cold.   I used a YETI cooler and it kept milk frozen for an entire day!  You can find it on Amazon, here!  Since our trip, YETI has come out with a backpack version of the cooler which I think is even better. Easier to carry on your back and it looks like it has more space.
  3. Pack the cooler with at one reusable ice block on the bottom and one on the top.
  4. Pack the cooler the night before your flight and put it in the freezer to stay cold.  Make sure the zipper is completely sealed close.
  5. Don’t open up the cooler again, but one time when required to at security checkpoint at the airport.  It’s tempting to keep opening the cooler and checking your milk.  Don’t do it.  Each time, you are letting warm air into the cooler.
  6. Security will inspect your breastmilk at the airport.  They will open the cooler and take out each bag of milk.  You can minimize the handling of individual packets by packing them in quart-size plastic bags.  If milk is frozen solid, they will only look at the bags.  If breastmilk is in liquid form, they will test each bag.  Which is why I recommend traveling with breastmilk frozen instead.
  7. Watch the security folks like a hawk and ask them to put on clean gloves.  You want them to know you are watching every move and that puts the pressure on them to work quickly to get milk back in the cooler asap.
  8. Once you arrive at your destination, put your breastmilk in the freezer right away.  If you cannot, transfer breastmilk to a deep freezer right away, place the cooler of frozen breastmilk in a large cooler with ice to continue to keep it cold until it can be put in a freezer.

Family packing car for road trip

Breastmilk storage

21 thoughts on “How to Keep Breastmilk Frozen for 14+ Hours While Traveling”

  • The cooler you linked is the 12…there is an 18 one on there which I assume is bigger- would that one work for a carry on as well do you know??

    • Hi Ashley, you know I am not quite sure. I know the 12 can one easily fit under the seat of the plane or up in the overhead bin. The 12 can cooler dimensions are: OUTSIDE 10” × 11 1/2” × 12 5/8”.

      And according to the FAA, The maximum size carry-on bag for most airlines is 45 linear inches.

      The 18 can cooler dimensions are: OUTSIDE 10 3/4” × 13” × 16 1/4” – which is still less than the 45 linear inches limit. But I am sure it will depend on the airline. Not seeing the 18 can cooler in person, I am not sure if it would fit in the overhead bin. But, I was able to easily fit over 100 oz in the 12 can cooler… just for reference.

  • Thanks for writing this! I have about 100 bags to move over 20 hours of traveling. Do you think I need two coolers?

    • Hi, Ally! Couple questions: How many ounces are in each bag? Are you moving via plane or car?

  • This is seriously a life saver ! Thank you! I’ll have about 250 ounces to take. Do you think the dimensions mentioned for this cooler will hold that extra 50 ounces? I am not sure we can get the yeti but I’m hoping to find a similar cooler! Thank you!

    • Jessica, I was able to put about 200 ounces in the cooler I had, I could have probably gone bigger and still been able to carry it on the plane. Let me know if I can be of more help. Please feel free to email me at

  • did you check your cooler or did you bring it on as a carry on? I assume you did a carry on…since they checked your milk. why didnt you check the bag?

    • I brought my cooler on as a carry-on. I didn’t check the bag because I wanted to have my eyes on the milk at all times…my Type A personality, lol!

  • I have 50 bags (medela) each with 6 oz of milk. So a total of 300 oz. I am traveling direct from US to Italy, about 9 hours at the end o f the month (so cold weather). I think it makes more sense to CHECK my milk in, as opposed to try to bring it on board. What do you recommend?
    My packing = put 6 bags in a freezer zip log bag, wrap each with newspaper, then inside a cooler lined on all sides with frozen gel packs or gel blocks. Then place the soft sided cooler inside of a hard shell suit case and check it in (use clothes/etc around it so it doesn’t bounce around).


    • Hi Yasmin, yay for having so much milk to transport. You could check or carry on. Pro about checking it is that you can transport it pretty easily. Con is you don’t have your eyes on it at all times. I’m not sure if TSA would open it and check it and i would be worried they may not repack it or seal it properly. Pro about carrying on is you have your eyes on it at all times. Con would be that finding a way to transport 300 oz in a carry on might be challenging but you should be able to fit it in a rolling bag.

      I think if you were to pack it like you said you should be fine. I would get frozen gel blocks… good ones that stay frozen. I’m personally a big fan of these yeti ones: they can be pricy but they stay cold forever.

      If you do check the milk/cooker make sure the packaging can easily be closed or sealed. For example, my yeti cooler doesn’t close all the way unless you do a little extra pull at the end. If someone else were to try closing it, they probably would leave the small gap at the end and not close it all the way. But if you have a cooler/bag that is super easy to close you should be good checking it. I think they way you would pack the soft sided cooler in a hard suitcase should be ok. Let me know if you have any other questions. Good luck! And how awesome to be going to Italy. We went. Last year and it was amazing!!!

      • Hi Yasmin and Lisa! How did you do with the 50 bags? i have 60 Packs (8 oz each) and need move from Philadelphia to California.. I have the yeti cooler, I don’t know if I need dry ice or just the frozen milks will keep it cold? What about the TSA

        • Hi Renata, The downside of using dry ice, is they recommend 1 lb of dry ice per pound of milk to keep frozen. So since. you are traveling with 480 oz you are looking at 480 oz of dry ice, and together that would be 60#. So a couple issues with that – it will be hard to find a cooler that can fit all of that. You will also go over the typical 50# weight limit for bags.

          If you are able to fit all of it in the Yeti, you should be good with 1 reusable ice block. I have never traveled with that much milk. I have only traveled with up to 200 ounces and that fit in this cooler:

          You may want to check with your airline, but I am under the assumption that you can bring an unlimited amount of breastmilk on as a carryon b/c it is considered a medical/crucial item. If that is the case, you could go with two smaller Yetis, like the one I got, or go with a bigger one. But you will want to make sure it can fit overhead. Perhaps you could also check it at the gate, which may give you better peace of mind instead of checking at the front counter.

          Let me look into some other options for you too and get back to this post if I find something else that could fit your 480 ounces.

          • Oh, that is a great bag! I like how it is long and lean. The trick to keeping it cold is not opening it if not necessary. So no, double checking it at any time….just keep it closed. You will have to open it at TSA, but if the milk is frozen, they will look at some of the bags… like pick them up, but not open them. Then once they are done, pack it back up and don’t open it again until you are done with your trip. I would put one reusable ice block on top of all the milk if you can. That will seal in the cold. Of the 20 hours, how much is going to be spent in the airport/airplane? Are you driving on either end of your trip for any length of time? If so, I recommend putting the yeti cooler inside another cooler that has ice for any lengthy driving.

    • Ok, me again…lol.

      I’ve been thinking about it and I think you will be better off carrying the milk on with you. Because it’s breast milk you are exempt from the 3 oz rule. And you have it in your possession at all times. It’s also in a controlled environment temperature-wise. If you check it, you aren’t sure what temperature it will be stored at. I thin in you do the exact same packaging you were planning, just put it in a carry on suitcase. One with wheels will be easiest.

  • Hello! Thanks for this.
    If the milk stays relatively frozen until destination arrival and immediately put in the freezer, are we allowed to use it after 48 hours?
    If it defrosts a little bit before arrival does this start the 48 hour clock?


    • Hi Asia, as long as there is some sort of frozen part still in the milk, it is okay to freeze. Only when it is totally thawed out (no frozen parts) that it needs to be used up within a certain time frame. I hope that answers your question.

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