DIY Upcycled/Repurposed Sweatshirt to Baby Sleep Sack Tutorial

Making your own upcycled baby sleep sack is so easy! If you have an old sweatshirt you can easily repurpose it into a fun sleep sack to keep your baby warm and cozy. Plus it will save you money by not having to buy a new sleep sack! 

Fall is definitely in the air. We woke one morning this week to a chilly house and we already had our first light frost a few weeks ago. We normally heat the house with our woodstove but it’s not cold enough to do that yet.  Until this week, we hadn’t thought about was how we are going to keep our little nugget warm at night now that she sleeps in her own room.

All last winter we co-slept so this was not an issue for us. We were given several baby sleep sacksas baby gifts last year but only one of them is big enough to fit our little nugget now. These are great to keep baby warm with a regular pajama underneath but we don’t have a lot of extra money to spend on buying new ones right now.

While I had my morning cup of coffee, I pondered what to do. Then an idea hit me: I could make an upcycled one! I remembered that I had a fleece sweatshirt in my upcyle pile. It is a little pilly but doesn’t have any holes so I figured it would work perfect.
I got out my scissors and our other sleep sack as a pattern and got to work. In about an hour, we had a fabulous “new” sleep sack for our little nugget. We’ve been using it all week and just love that something so simple could be the answer to keeping our little nugget warm at night while she sleeps! And the best part? It cost just a few cents for thread and snaps plus a little bit of my time and creativity!
The fleece shirt I had on hand had a taller neckline and zipper so there are a few extra steps in this tutorial than what you would need to do if you had a sweatshirt with a standard neckline. 
Supplies needed:
1 sweatshirt in cotton or fleece, youth large or adult size small work best
Store bought baby sleep sack to use as a pattern
Sewing machine
Snaps (I use plastic Kam Snaps)
To start, lay your sweatshirt down on a flat surface and make sure there are no wrinkles in it. 
 Lay the sleep sack on top centering it on the sweatshirt. 
how to make an upcycled and repurposed sweatshirt into a baby sleep sack
Cut around the sleep sack on the sides and arm holes leaving about a 1/2 inch seam allowance. Leave the bottom hem of the sweatshirt intact so you don’t have to finish the edges off. If your sweatshirt is a larger size and too long, you can cut the hem off to the length you want but will need to add in an extra step to finish the edge off. Leave the shoulder seems intact for now.
easy DIY tutorial on how to make a baby sleep sack
Next open the cut out sweatshirt, lay flat and finish off the armhole edges. I serged my edges and used white thread so it is easier to see in the pictures. If you don’t have a serger, you can finish the edges with a zig zag stitch. 
how to make a baby sleep sack from a sweatshirt or sweater
Next turn your cut sweatshirt inside out so the right sides of the fabric are together. Pin and sew the side seams from the bottom hem to the bottom of the armhole. 
Turn right side out and install snaps on the front and back bottom hem edge. I used four snaps placed evenly across the bottom. This will allow for an easy on/off and no need to fully undress for a diaper change. 
how to make a baby sleep sack tutorial
Since our sweatshirt had a taller neckline, I cut it down and finished the edge off by serging around the neckline. This also meant that the top edge of the zipper stop was gone. This is an easy fix, just hand stitch around the top edge of the zipper track on either side. Make sure you have enough stitches to create a good stop so the zipper will not pull off the top. 
 Depending on the neck width of your sweatshirt, you may need to sew it smaller. Lay your sweatshirt sleep sack out flat with your sleep sack pattern on top to size up the width of the neckline. If yours is too wide like ours, place a pin on the sweatshirt neckline on either side where the pattern sleep sack neckline stops.
how to sew a baby sleep sack from a sweatshirt or sweater
 Then sew from the pin across the shoulder to the top of the armhole creating a new shoulder seam with a smaller neck opening.
If your sweatshirt did not have a zippered neck, you can be done at this step. The next few steps are how to add on a protector strip to go over the top of the zipper. Our little nugget is at the age where she is fascinated by zippers so I needed to hide it and also cover up the metal zipper so it does not rub against her neck. 
To create the zipper cover, cut a piece of fabric at least two inches wide and long enough to cover a good part of your zipper when folded in half. I used the cuff off of the sweatshirt. Finish off any cut edges by serging or sewing with a zig zag stitch. 
Turn the sweatshirt inside out. Fold the zipper cover in half and place over the zipper with the fold covering the top edge of the neckline centered over the zipper. Once you have it centered, open it out and pin one edge of the zipper cover to the fabric next to the zipper and sew in place from bottom edge of the zipper protector to the neckline. You will only be sewing one side of the bottom half of the zipper cover to the main body in this step.
how to turn a sweatshirt or sweater into a baby sleep sack
Turn right side out, pull zipper up into place and fold zipper cover over top. Install snaps to secure zipper cover to the main body of the sleep sack on the front. 
how to make a protective cover for a zipper on a baby sleep sack
I also added a snap on the inside that attached the one side of the zipper cover that was not sewed on to the main body so the zipper can continue to be used. This will help to keep it in place but allow for it to be unsnapped so the zipper can be pulled down.
Now you’re all done. Time to go put your “new” upcycled sleep sack on your sweet babe to keep them warm!
DIY sewing tutorial to make a baby sleep sack out of a sweatshirt or sweater
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  1. says

    i love this! and i actually think this is something i could handle making with my limited sewing skills. :) i would never have thought to add snaps to the bottom for closure. thanks so much for sharing this!

  2. Anonymous says

    I wonder if it might be easier….. and more baby-friendly… remove the zipper entirely and sew a wide band on either side that will overlap and you can add snaps to. You can fold the bottom under and topstitch. The bands can be made out of scraps or a decorative remnant from something else.

    • says

      That’s a good idea too! Actually we haven’t even been using the zipper lately and just put it over her head all zipped/snapped up with no issues. Ideally I think it would just be easier to upcycle a regular neck sweatshirt and not have to deal with a zipper at all but this was all I had in my upcycle pile at the time :)

    • says

      My husband actually bought me the serger as a Valentine’s gift right around the time I opened my Etsy shop last February and was the BEST gift ever :) You should totally check out the KAMsnaps web page, they run occasional sales on their snap pliers and you can get a set for a really good price. I bought a pair last summer that were seconds and all we needed to do was add a little oil so they wouldn’t squeak. I got them for making diapers and now I use them for all sorts of things. No need to buy a really expensive snap machine (unless you do tons of snaps all the time) when you can get a really affordable pair of snap pliers. I did a lot of research on snap pliers last summer and it seemed KAMsnaps ( were the most recommended although there are other brands out there :)

    • says

      Thanks for stopping by! I am saving the link to your blog hop in my list of weekly link ups so will definitely join in. I can’t wait to check it out, I LOVE upcycling/repurposing things and am always so inspired by seeing what projects other folks come up with :)

  3. says

    How clever! I really like the instructions for the zipper cover, as I would have struggled a bit with that. I think I’d stick with a pullover if available, but great way of upcycling what you have!

  4. says

    I ended up making a sleep sack for my niece for Christmas – my sister-in-law said she was down to one that fit, and my niece only slept through the night if she was in that sleep sack. So easy to make, and so nice for parents who don’t want to increase their heating costs. 😉

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