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 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.

Keeping breastmilk frozen while traveling, whether for a vacation, a one-way move, or something in between can feel a bit overwhelming. Follow these tips to help keep it simple and reach out to me if you have any questions along the process. I’ve helped numerous moms troubleshoot how to travel with breastmilk and I’d love to help you too.

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Family packing car for road trip

Breastmilk storage

46 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.

  • Hi Lisa,
    I have been researching how to properly move my stash of milk. I currently have 3,500oz of BM. They are in bricks of 60oz. I was planning on using the dry ice option but after reading your post, I’m a little worried about the dry ice effecting the milk. I will be traveling from
    Japan to California. Travel time Would roughly be 19hrs almost 24hrs till I would be able to get my milk to a deep freezer. I have not seen any yetis that are big enough to transport the milk i have. Just the igloo brand so far. I will also be traveling with my three kids and husband. I also plan on obviously checking in the cooler. Thank you for any suggestions you may have

    • Hi! Thanks for reaching out. Congrats on being able to save so many ounces of breastmilk. I recommend three things: (1) check with the airlines to see if they have a limit on how heavy an item can be with breastmilk. This will help you determine what kind of container to use. (2) Dry ice might be your best bet b/c of almost 24 hours travel time. You can wrap your bricks of milk in plastic wrap to protect them a little bit better. The only downside of this is that you will need equal parts of dry ice to breastmilk, so you are looking at transporting 7000 oz which is over 400#. (3) If you can find large enough coolers to hold all of the milk, I would just make sure that they do not get opened from the minute you pack them up and leave to the minute you get to your new home.

      I wish I could be more help, I am just not familiar with carrying this much milk internationally. The airlines may be more informative than I have been. Sending you lots of luck on your trip!

  • Hi! I plan to travel just from California to Las Vegas. About 1 hour and 45. Minute flight. Probably will be a total of 5 hours travel time from when it comes out the freezer and gets to another freezer. I don’t want it to thaw at all! If it’s frozen what is the best way to pack it so security doesn’t take it out for too long? And do you use the yeti brand ice blocks? If not what do you recommend for the 12 Yeti cooler you attached?

    • Hi Jade, I have used the yeti ice blocks too. I usually pack one ice block on the bottom, frozen milk on top of that, and then another ice block on the top. This all depends on how much space you have. If you are short on space, remove the ice block from the bottom and use only one on top of all of your frozen milk. Remember, while I don’t think it will melt at all in such a short time, frozen breast milk that has started to thaw but still contains ice crystals can be refrozen. And a key tip to also remember… make sure the zipper on the yeti is completely closed. Avoid opening milk to check on it– it will stay frozen for these 5 hours. Good luck on your trip and let me know if you have any other questions.

  • Hi Lisa, thanks so much for this! We will be traveling 10 hours via plane and this helped me so much! Curious what size ice block you used for the yeti? They have 1,2 and 4lb options?

    • Hi Britni, I used (2) 2 lb. ice blocks for most trips. When I did my big haul with the most, I only used (1) 2 lb. block. Hope this helps. Good luck on your trip!

  • This is sooo helpful thank you! I have 80 oz of breastmilk to transport through TSA! What size freezer blocks did you get? 1 pound? 2 pound?

    • You’re welcome! One time I did the 5# block in the bottom of the cooler. Another time I did a few 1# blocks because I needed more space for milk.

  • Thanks so much for this post! This is incredibly helpful. I am traveling for work in a month and will be gone for 4 days. I will need to pump while away. Unfortunately I don’t think I will have access to a freezer. If I keep the pumped milk in the fridge and then put it in the Yeti cooler to transport, do you think that will be okay? I realize the guidance for refrigerated milk is 4 days so I may need to throw out some of the milk from the first day. Any advice would be greatly appreciated. Thanks!!

    • Hi Amanda, thank you for reaching out. If you don’t have access to a freezer, I would keep it cold either in a fridge or cooler with ice. Adding more ice a couple of times per day. And you’re right, you have 4 days to use or freeze refrigerated milk. Personally, I would keep milk from Day 1 and use it in a bath or put it on your baby’s skin. Milk from Days 2-4 can be used right away when you return, using Day 2 first. Or you can freeze the milk from Days 2-4 once you return and use it later if you don’t need it immediately. I hope this answers your question.

      Bring all of your milk back in a sealed cooler, like the Yeti. Bring one cold pack with you to put in the cooler and keep it stored in the fridge so it is somewhat cold. Then, put a few bags of ice in the cooler on your way to the airport. Get rid of the ice in those bags before security because they won’t let it through if has melted at all. Then refill those bags for ice once you pass through security. They may test your milk at the airport security if you’re flying. Be prepared for that… since it would be liquid. Random note, but sometimes you can set a hotel fridge to its coldest setting, and it may freeze your milk. Check that out if it’s an option. If you have any other questions please feel free to reach out.

  • Thank you for this info! My head is spinning as I am planning a trip to Italy with my Grandmother who is turning 85 (her first time, and a once in a lifetime opportunity I can’t say no to) and all the most important women in my life are going too (Mom, Sister, SIL, Aunt…). I am nursing a 6mo and will need to pump while I am away for 10 days. It’s such a long time to be away and I have a lot of anxiety about it for various reasons I’m sure fellow moms can relate to. I believe I will have a fridge at the least at my hotel room, I am going to ask if they could freeze milk for me, but not sure what to expect). We will be in the same hotel for 6 days, then another hotel at the end of the trip for 3 days. I have the Ceres Chiller for on-the-go cooling and am in the market for a cooler bag for the transport portion when it is time to go home (like your YETI). If I have calculated right, I think I could end up with a max amount of around 200oz – give or take. My goal is to be able to bring home at least 100oz (trying to be realistic in case I can’t freeze milk at all, or need to skip saving some because of unforeseen travel timing, etc). Considering the ICEMULE backpack for a cooling option for bringing my milk home – it folds up for travel so one way I won’t have to have it out (just my ceres chiller to store fresh milk which can go in my carryon). They have various sizes for the ICEMULE and I am not sure what would work best for the amount I expect to have? How big was your YETI that you fit 200oz in? I plan to use bags frozen flat if I can as well. Alternatively, Corkcicle makes a nice cooler backpack (either their Lotus or Eola backpack coolers) that I am thinking could double as a carryon going to Italy, and storage for the way home?

    I am also having trouble finding info about flying with milk FROM Italy. Do you or anyone reading this message have any knowledge regarding the rules in that country? Thank you for the help!

    • Thank you for reaching out! This trip sounds amazing. If your hotel could freeze it for you, that would be amazing. Let’s say they can freeze it. For best keeping, I would use a cooler like the Yeti with up to 3″ of polyurethane foam insulation. Transport from Hotel #1 to Hotel #2 and put back in the freezer at Hotel #2. Then pack the cooler right before you leave for the airport to come home. I would assume you will have about 200-ish ounces to travel with after ten days. I used the Yeti Hopper Flip 8 cooler (not the 12 that I had orginially posted here) to fit 200 ounces. The bags were all very flat so that they could fit easily.

      If the hotels can’t freeze it, you can only refrigerate it for four days. You could still keep the refrigerated milk after four days but only use it for bathtime, not consumption.

      I hope this helps. If you have other questions please don’t hesitate to reach out. You can also reach me via email at lisa @ movemamamamove . com

  • This was helpful, thanks for posting, I will be traveling for 18hrs internationally. That’s just the flight itself, with all transportation and waiting time the frozen breast milk will be out for about 23-24hours.
    I plan to bring 60oz of breastmilk. I was thinking of getting the Yeti Daytrip since it is not as bulky as the other coolers and I plan to bring it as carry on. Do you think that will be enough? Any suggestions? Thank you!

    • Hi Hannah, thanks for reaching out. I haven’t used the Yeti Day Trip, but I did a little research on it. I see that things stay cold for about 12 hours. Which may not be long enough for your trip. There are reviews online that say contents get warm by afternoon if packed by morning. Question for you: do you have a freezer available at your destination? If yes, then it’s okay if things start to melt as long as they don’t fully melt. Even if thawed breastmilk still has some frozen pieces, it can be re-freezed again. If it melts completely, you must use it within 24 hours. If you don’t have a freezer at your destination, I would recommend the yeti hopper flip 8. It might seem a bit bulky for 60 ounces, but then you can be sure that things will stay frozen. I was able to take this one on as a carry-on because it was small enough. If you have any more questions, please let me know.

  • Just wanted to say thank you for this post! I followed your tips, bought the Yeti Hopper flip 12 cooler, and two of the Yeti 4lb Ice Packs. I just travelled 36hrs from Portland, OR to Perth, Western Australia with 100oz of frozen breastmilk and every single bag is still around 90% frozen!!!! The cooler was opened/inspected 3x on the journey and I carried it onboard with me throughout. I’m in awe and I honestly think it could keep them frozen for a couple more days if I needed. 10/10 recommend this way of traveling with your liquid gold<3

    • Catalina! This is amazing!! I love to hear this. So glad it worked out well. What a great testimony to how awesome the yeti is.

  • Hello! I will be traveling from NYC to Florida with about 240 ounces of frozen breast milk (about 30 flat 8 ounce bags). What cooler and ice packs would you recommend to keep them frozen?

    Thank you!

    • Sorry! I am just catching this comment. I hope you were able to find a cooler that worked best. Did the Yeti work out okay for you?

  • This is so helpful!! I am getting ready to take a trip for the first time with little one (8mo) and was freaking out about how to travel with breast milk. I really only need to take about 50oz for around a 10 hour trip. If I am taking a smaller amount of milk do you have any recommendations for packing different to the above? I wasn’t sure if the reason most of yours stayed frozen was because it was packed in so tightly. If so, I may need a smaller version of this type of cooler since I am traveling with a smaller amount of milk and would need it to stay packed tightly. If it doesn’t matter really how tight it is packed, that may not be an issue but wanted to be sure. Also, have you found any other coolers that you liked that were similar to the Yeti? My husband is just not a fan of Yeti and isn’t excited about buying another (we’ve had two crap out on us) from that brand. Additionally, would you recommend the 1lb, 2lb, or 4lb ice pack for the amount I am taking and length of travel? THANK YOU so much in advance, I cannot tell you how much this eases my mind already!

    • Hi Alexis, I haven’t sampled a smaller cooler. But the yeti hopper flip 8 might do the trick. Not sure if it wills till be took big. They also have a lunch box that many people said kept their items cold for hours. So that is smething to try too. Maybe if you have time, order one and see how it holds up with a baggie of ice. As far as ice packs go, I would go for 2, 2lb blocks. One on top and one one bottom to keep milk extra cold. Let me know if you have any other questions. Good luck and safe travels.

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