How To Make Your Own Microwavable Heat Pack (With A Washable Cover!): Sewing DIY and FREE Pattern

by Meghan Fowler

We are kind of heat-pack fanatics here. And apparently we are not alone — so many people have a secret love for these precious microwavable bags. And no wonder! Nothing like wrapping one of these deliciously warm packs around cold toes, or soothing sore neck muscles with its therapeutic heat. When I am cold and I can’t get the chill out of my bones, my heat pack saves the day (or the night as the case may be!). And it doesn’t squirm away from my icy feet like my husband does – ha!

Our old store-bought (Magic Bag) one lasted a long time, but it didn’t have a cover and was used SO OFTEN and for SO LONG that it looked very grimy and I was persuaded that it was likely harboring a host of germs and needed replacing. I knew that I’d want to make my own next time because: I love DIY. And it’s more budget-friendly. And I wanted the choice of grains. And I was digging the fun idea of making a cover for it.

The great incentive I needed to put this project on the top of my to-do list came last week when it split a seam and spilled oats everywhere. Oddly, this happened after my little brother used it. Just saying.

(Kidding! It was on its last legs.)

This tutorial isn’t for just any heat pack. It’s for a sexy contoured one, meant for going over your upper back and neck. Magic Bag makes ones like this, and they are fabulous. And ours lasted a LONG time. So if you don’t have time or inclination to do this project, go buy one, you won’t regret it. You’re welcome.

HOWEVER, if you want to make your own, it’s cheaper, and you can choose what grain you like best, and you can pick a fabulous print that you adore so that you feel “stylish” wearing it. Nothing says middle-age-fashion like an over the shoulder heat-pack, now does it!? AND you can wash that darn cover, to boot, which is a HUGE perk in my opinion. So get out your sewing machine and some nice looking cotton and let’s get started:


  • A 13″x44″ piece of sturdy cotton (like a scrap from a sturdy old sheet) for the actual heat pack
  • A yard (36″x44″) of cotton for the heat pack cover. You won’t use all of it, but half a yard isn’t quite enough either. I was tempted to try cotton flannel, but opted not to this time. You could try it though!! (And tell me about the results!)
  • Matching Thread
  • Fabric chalk
  • Iron / Ironing board (a stack of towels will do!)
  • 6.5 cups of the grain of your choice*

*regarding grain to use for filling the pack, this post by A Little Crispy was really helpful. Based on her research, I went with Jasmine rice, which is heavier than the oats were, but really does hold its heat longer in my experience. And it smells good too. So two thumbs up for that!


First. Grab your FREE PATTERN here:


I made this pattern using my old bag as inspiration. I designed the cover to be the slightest bit larger than the neck bag itself because who wants to wrestle with putting it in its’ case? Not me. Not you. That’s who. This is the first time we have ever made a PDF pattern. So, congratulations, you are the very special guinea pigs trying this out!! We would love to hear how the pattern worked for you!! (Constructive comments only please!). 

Open the pattern in Adobe Acrobat Reader and print it at 100% scaling. Print only page 1 to start, and measure against the scaling square to be sure everything is printing at the proper size. Then carry on printing out everything else. You only need to trim and tape pages together when there’s a triangle along the edge. Okay? 

Pages are laid out like this:

picture of the pattern layout

Using the Heat Pack Body part of the pattern, trace and cut out TWO of the neck bag shape out of sturdy cotton. And Cut out ONE each of the 3 cover pieces, taking care to have the pattern facing the direction you want it to. Now grab your two Heat Pack Body pieces and pin (or in my case, clip) them together, wrong side out.

Picture of fabric pinned together

Sew a straight stitch around the entire edge of the bag with a 3/8″ seam allowance, leaving a 5″ gap in the bottom so you can pour in the filling. Make sure you go back around with a zig zag stitch after to prevent fraying and make for a stronger seam. Now turn the pack right-side out and press it.

picture of heat pack with gap for filling

In order to prevent the filling from all falling to the bottom or back of the bag when you’re wearing it, it’s important to sew a fancy (or not-fancy) line in each side (let’s call each side piece an “arm”), like this. This line will help divide the grain evenly. You’ll see.

pics of ways you could draw the lines on

Next, fold the fabric down the middle and lay it down so the line you just drew is on top.

picture of a pin through heat pack

Use a pin to poke along the line every inch or so, making sure you go right through to the other “arm” (which is directly beneath). This is how you’ll get the exact same line on the other “arm” of the pack. Like such:picture of a close up of a pin

Open it back up and find the little pin prick holes you just made along the other arm. Use your fabric chalk or marker to draw in the pin prick line so that you have a symmetrical heat pack. Now sew along these lines (again, make sure the bag has already been turned right side out at this point!!). Next brush off the chalk lines (or wash them off). Then FILL the pack with 6-6.5 cups of the whole grain of your choice (I did white jasmine rice). Make sure when filling that you get some down into each section of the bag. I.e. get some on each side of the lines you sewed in the “arms” of the pack. But don’t worry too much, if it’s not evenly distributed you can distribute it more after you sew it closed. Which it is now time to do. Turn the exposed seam in and pin it, and then sew over it a few times.

picture of the filled heat pack

Next, make the heat pack cover!

First hem the heat pack cover back bottom opening. Roll the straight edge 1/4″ and then 1/2″ over and press to make a clean hem.

picture of Ironing the hem still more

Sew this hem with a 3/8″ seam allowance. Do the same thing with the straight edge on the heat pack cover back upper opening.

Place the heat pack cover front right side up on your work surface. Lay the back lower piece right side down on top of the front piece. Then lay the back upper piece down, lining it up with the edges of the front piece, with the hem portion overlapping the back lower hem. It should look like this (except with a seam in the hem, which is missing in my pic! oops!):

picture of heat pack cover inside out showing cover opening

Sew the entire way around the edge using a 3/8″ seam allowance. Trim away the excess fabric.

pic of excess fabric trimmed off

Go once around the perimeter with a zig zag stitch to prevent fraying and strengthen the seam. Now turn it right side out and press! picture of finished cover front view 1 finished cover back view picture

Shimmy the cover onto the filled heat pack and you are ready to rock and roll! To use, pop it in the microwave (with a mug of water so it doesn’t dry out) and microwave for between 90-150 seconds (but start small — you don’t want to burn yourself. Try heating it in 30 second increments at first until you know how long your pack needs).

So there you have it, a simple tutorial for making your own heat pack! Thanks to this, you will never be cold or sore again (I wish. But I promise it will help!).

pic of meg wearing pack

See how happy I am wearing this? 😆 Friends, if you make one, I would be so thrilled if you tagged me @undertheelms so I can see the finished result! And if you haven’t already, please join our email list for more Under the Elms goodness! Do it! (Sign-up right there on the sidebar 👉👉)

picture of alt back view meg wearing pack

If you love this, PIN it 👇 for future reference!!

picture of heat pack pin for pinterest


Stay warm, friends!



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