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How to Make a Freezer Bag Cooking Cozy

If you’re into Freezer Bag Cooking, then you should consider bringing along a freezer bag cozy to keep your food warm while it re-hydrates. This is particularly helpful in the early spring, autumn, and wintertime when colder weather will quickly cool hot water in an uninsulated Ziploc bag.


This is an easy DIY project. To get started you need a roll of Foil Bubble Insulation and a roll of Reflective Foil tape. The bubble insulation consists of a layer of polyethylene bubble wrap sandwiched between two sheets of aluminum. This stuff is easy to find at Home Deport or a well-stocked Ace Hardware store.

Roll of Reflextix for Homemade Backpacking Gear Projects
Roll of Reflextix for Homemade Backpacking Gear Projects

The first step is to cut two pieces of the foil bubble insulation with the same width. The stuff is very soft so common household scissors are fine for this task. Next cut one of the pieces down about 4 inches. You want the foil bubble insulation piece to be slightly wider than the freezer bag since you’re going to tape them together to form a pocket-like envelope. I usually allow for two foil columns on the left and the right of the Ziploc and use that as a guide.

Next, stack the shorter piece of insulation on top of the longer piece, and cut three lengths of reflective tape tp join the sides and bottom together.

Apply the reflective tape to form an insulating envelope and cut off any excess around the edges. Fold the longer piece over the shorter piece and you’re done. If you want to be extra fancy, you can also add some velcro tape to the inside of the flap and the outside of the insulated envelope to keep the cozy closed while your freezer bag meal is cooking.

The weight of the freezer bag cozy shown here is 1.7 oz.

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  1. Using your sleepingbag could be a useful alternative.

  2. Nice! My cozy isn't as cool, I'm going to have to give yours a try.

    In regard to the other comment, I don't think putting food inside one's sleeping bag is a stellar idea… animals have great sniffers!

  3. I'd also be hesitant to use my down sleeping bag as freezer bag insulation Spilled/leaking water and down make poor sleeping companions when it's cold enough to need a freezer bag cozy.

  4. Very cool!!! If I didn't already have a couple of the fabric ones, this would be fun to do. Great info.

  5. The ones made of Reflectix work well and are very easy to do.

    While one can use a hat, jacket, etc as a cozy (since a cozies function is to insulate food so it can cook) – I would suggest strongly that a person uses a dedicated cozy, be it Reflectix or a fabric one, such as we make. That way the cozy can go in your bear bag, Ursack or canister at night :-)


  6. Definitely – you wouldn't want your Freezer Bag cozy to be your sleeping bag in grizzly country. Very bag idea and it's hard to get it to fit in a bear cannister, too.

  7. Oops, I added my comment to the wrong post earlier.

    I just made a similar freezer bag cozy out of a reflective padded mailing envelope I bought at Target for $1.60. It's probably not as sturdy or as efficient as yours, but its cheaper than buying a roll of foil insulation.

  8. Nice! – you've reminded me that you can also use a plastic mailing envelope with bubble wrap insulation as cozy too. I did this a few years ago before investing in the huge roll of reflective insulation you see in the article.

  9. You can get the insulating foil stuff in the auto section at Walmart for ~$5. They are the sun blockers for windshields. No big roll leftover after the project. It is more like foil bubble wrap, but it works great!

  10. A couple of the self adhesive velcro dots work great for keeping the flap closed.

  11. Since I already have everything here, I think I'll make one of these. I used my knit hat as a cozy but ended up as a Mac 'N Cheesehead–I guess it's good I rooted for the Pack in the Super Bowl. I don't think I'll try the sleeping bag. The first time my grandson backpacked with me at age four, he spilled a bottle of chocolate milk into his brand new Marmot down bag. I don't want to go through that kind of clean up again.

  12. Nice. Really enjoyed your talk at the REI on the 4000′ ers.. Gearing up my backpacking season with my first DIY freezer bag cozy thanks to this post.

  13. You can reduce the number of seams and amount of tape by using a single long rectangle, just fold it into an envelope shape and tape the sides. It’s probably a bit more insulating as well.

  14. Our senior Scouts just headed to Arkansas this week for about 40 mile backpack and used these cozys along with my kelly kettle to make sure they ate well. Our favorite – couscous tacos.

  15. Just built this for 2014 – used duct tape instead of reflective tape and added a couple of velcro tabs to keep it all in place. Thanks for the idea.

  16. This also works in reverse if you are carrying any cheese or summer sausage for multiple days on the trail. Just keep a bottle of cold water in the cozy with the food that can spoil during the day and replace it at night and you can get the perishable food to last a day or two longer.

  17. Nice idea…On cold winter days, I prefer to keep it cozy under my coat. This serves two purposes; it keeps my food warm, and warms me up while I wait. I use a spare ziplock to guard against leaks.

  18. Thank you for these instructions! It worked beautifully and I made a personalized cloth cover to put it in.

  19. I would recommend using duct tape vs. reflective tape. Reflective tape when folded often forms sharp edges which can tear/poke holes in clothing/gear – mine even put a small puncture in my water bladder and tore the hydration sleeve inside my backpack.

  20. Using the sleeping bag or a down balaclava is not risky at all provided that you double-bagged your freezer bag.

    • Unless you live in grizzly or black bear country. I don’t recommend putting food near your sleeping bag, tent or under clothing of any sort.

  21. Do you have to use the reflective tape? Would packing tape work? Is the reflective tape particularly heat stable? What about other types of tape that high-heat stable (are there any)? [I’m asking for this project and also out of general curiosity]

  22. Great idea. I usually stuff it in a pocket, but having it close at hand reminds you that you want to eat it…..usually too soon. And it can double as cushioning for you Kindle if you make it the right size!

  23. These are very good & cheap, but ever since I got my Big Sky…game over.

  24. Made this and it works great. Super easy to make too. For 17 dollars (cost of tape and insulation) I have made several of them for friends too. I added some Velcro so I can fold it over and keep it closed.

  25. Started making and using these “cozies” back in the 90’s and just after the turn of the century (I love being able to say that) when I was still Scoutmaster for on of the local Boy Scout troops. Fantastic at ensuring your meals get fully hydrated while remaining warm. Drop the meal into the cozy, seal it over and walk away for 10 minutes. Open it up, stir the meal, reseal and walk away for another 10 minutes. When you come back, not only is the meal FULLY rehydrated, but it’s still hot.
    Over the years, we’ve found many other uses for these. Here’s a short list of those uses:
    1) butt pad – much more comfortable to sit on than rocks, logs and the cold ground. Most popular use!
    2) extra insulation for cold spots at night
    3) splint – broken down, it can roll around a wrist, ankle, whatever and be taped or tied in place to isolate injuries
    4) signalling device – when new, the reflections from this can be seen from a long way out
    5) pillow – fold or roll it up for more support under your head at night
    6) emergency insulation – cut the tape and use it as an extra layer between you base and outer layers of clothing
    7) kitchen sink – If you’ve taped well, fill partially with water to wash your dishes and/or socks (rinse well if you’re going to use it for food after washing your socks or breakfast could smell a bit less appealing than usual)
    8) Emergency insoles – yep, actually had to use one for just this purpose once with one of my scouts
    9) fishing creel – but that’s the last time it’ll be used before disposal. ha
    10) kitchen table – gives a flat, clean spot for food prep before being used as a cozy.
    The handiest piece of equipment I carry and at just over an ounce, why do without it and why not carry a couple? After all, as soon as you pull it out of your pack, if you don’t sit on it immediately, someone else will!

  26. In my ultra-light-headed moments, I use my kozy as a sit pad too (though not with food in it). It’s also a nice flat surface on which to put some of the stickers I collect from hiking-related websites, vendors and such.

  27. I made 14 of these for a teen backpacking trip I’m leading in 2021. After following the instructions, I finally decided to eliminate the bottom seam by folding the material versus cutting and taping. Saved on tape and time. I hope the teens treat them with respect so I can reuse them on another trip.

  28. I would like to suggest also to use a single rectangular piece, but create a gusset at the bottom so that the cozy can stand upright when the gusset is stretched out. That way, the hot meal won’t tip over. There are instructions on youtube on how to do this, but basically, just fold an extra crease at the bottom. Also add a velcro on the flap to keep the heat in.

  29. I have tried various tapes, including the foil tape, but by far the best is the thin and flexible mylar tape. It’s very similar to the reflective surfaces of the reflectix itself, follows the little bubbles and dips, and adheres as well or better than anything else I’ve tried, doesn’t crinkle up and detach over time. Got it on Amazon.

  30. I’ve made a couple of these. They do make a good knee pad for use while entering or exiting a tent.

    For me, a nice thing that started as an oversight was that the bottom corners weren’t watertight. I found that to be useful because it allowed spilled water to drain easily.

    As far as taping is concerned, I first used aluminum flashing tape but found it unsatisfactory. Through use, it tore and left somewhat sharp edges and I field repaired it with Tenacious Tape. Tough plastic tapes such as aluminized Mylar or even packaging tape should work. Duct tape might possibly be affected by the heat and leave a gooey residue. A roll of the material is cheap enough that it’s easy to make a replacement if your first attempt isn’t satisfactory.

  31. An issue I’ve found with Reflectix if used as a sit or knee pad is that it’s VERY slick and will slide easily on unlevel ground, especially if it’s wet. Of course, that shouldn’t be an issue with a freezer bag cozy.

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