Upcycled Tracksuit Jacket from Mattress Cover | New Look N6142

I made a soft, cozy DIY tracksuit jacket from a mattress cover. Okay, I did this upcycle project for kicks and to spark some creativity.

A while ago, I made bench cushion covers for our camper van. So, we had all this fabric and I wanted to use it up.

I’ll tell you all about the sewing pattern I used, materials, my process, plus share photos. You might transform something unconventional too!

New Look N6142 Loungewear Pattern

If you’d like to make a tracksuit, New Look N6142 is my favorite. This is a misses’ and men’s separates pattern for loungewear or activewear. 

You can make a knit tank top, sweatpants, and a hooded, zip-up jacket. I bought this pattern a long time ago, and it’s still available online. 

It’s easy to sew and has the basic pieces to build a nice set. I’ve pretty much made all versions, and they came out great. 

Materials

Here are all the things I used for this project. Oh, and I didn’t have to go too far for fabric! 

Fabric

For my project, I used the original covers for the mattresses we bought for the van. They were made with soft polyester stretch fabric.

I’m not sure what else is in the material, but I know it’s synthetic. There’s a quilted design, and that’s why I thought it’d make nice outerwear.

People create tons of textile waste a year. Why not try to upcycle fabric as much as I can?

The material tag indicated that the fabric is washable, so that’s a plus. I can tell it’s a double knit. 

Suggested fabrics for the tank top and pants should be made in stretch knits only, such as cotton interlock, jerseys, and stretch velvet. In addition, the pants can be made with nylon sport fabric.

For the sweatshirt, it’s recommended to use double knits, fleece, or sweatshirt fleece. 

Notions

You’ll need 5/8 yard (0.625 inch) of 3/4 inch (0.75-inch) wide cotton twill tape. I think I’ll use thinner twill tape next time though.

For the drawstring, you’ll need 1-1/4 yard (1.25 yard) of 1/4 inch (0.25-inch) wide cord of 1/2 inch (0.5-inch) wide cotton twill tape. For the front closure, get a 24 to 26-inch separating zipper, depending on the size and length you make.

Needle

I used a size 80/12 ballpoint needle for this fabric, but was on the fence about using a 90/14 needle. The size 80/14 needle worked great on this thickness. 

If you have thicker fabric, you might consider using a size 90/14 or even a 100/16 needle with sweatshirt fabric.

Thread

For my sewing machine, I used matching Gutermann sew-all thread. It’s a universal sewing thread made of 100% polyester.

For the serging, I used Maxi-Lock serger spun thread for overlocking. It’s also made of 100% polyester.

Sewing My Jacket

Making this garment was pretty straightforward once I got it cut. That took time, but it wasn’t terribly bad. 

Prepping

I started by pre-washing the fabric on delicate. Then I threw it in a cool drying cycle.

When cutting, little fibers came out of the material. That’s how I knew it was synthetic because they seemed plasticy. But this stable knit was easy to cut and so soft. 

The mattress covers had a long zipper around them, so I had to remove that first. I was able to salvage the zipper and as much material as I could.

When upcycling, you might have to sew large pieces of fabric together. I lucked out with the mattress covers being so big and there was plenty of material to complete my project.

I didn’t make a mockup because I’ve made this sewing pattern many times before. The sizing runs true to size.

I made my adjustments at this time. After that, I traced out my cut pattern pieces and marked them.

This time, I used a disappearing ink fabric marker to make my markings. I didn’t want to use wax because it might not come out on the white fabric. 

That has happened to me before, and I learned my lesson.

You know when they say to test it on a piece of fabric? Well, I don’t always do that… and guess what happens?

I kept all the nested sizes on this sewing pattern so I could make garments for others. So after tracing the pieces, I cut them.

And yes, my cutting mats aren’t pretty. They’re all scratched up after years of use. That’s just how it is.

Construction 

I followed the directions step-by-step, which were easy to understand.

Sewing the pockets came first. These are rounded with a side opening.

I don’t usually sew these types of pockets, but I’ll tell you, I really like them. Plus, they’re nice and big.

Then I sewed the front to the back. This has to be done with care so that you don’t sew the pocket openings into the side seams. 

I made sure to re-check my pocket seams and seam allowances so they were very accurate.

When it came to sewing the hood to the back, I added the twill tape binding. I followed the pattern directions and used 3/4 inch (0.75-inch) twill tape.

Next time, I’ll use 1/2 inch (0.5-inch) twill tape. I didn’t need it to be so wide. So you might consider using 1/2 inch (0.5 inch) instead.

I had a metal zipper in my stash and used it for the front closure. The navy color was a nice contrast against the white.

It wasn’t too heavy for the weight of the fabric. But I typically reserve my metal zippers for denim and heavy woven fabrics. 

It was long enough, but an inch longer to be perfect. Oh well, it worked fine.

Adjustments

You’ll see that my finished hoodie is a little big on the dress form. That’s because I made this fun piece a size medium for someone else.

When cutting the arms, I had to lengthen them about 2 inches.

I also added length to the jacket to make it longer. My method is to use my gauge to measure and then draw on the fabric before cutting. 

Finishing Touches

I double topstitched where I could, including on the pockets. I didn’t add the drawstring in the hood, because I was asked not to.

For this upcycled fabric, I did have to serge all seams. Typically, with knit fabric, you do not need to serge or finish the ends.

Knit fabric does not unravel, but it has a fuzzy fray. So I serged the fabric to stop it.

Project Notes

Before you upcycle material or buy fabric off the bolt, make sure it’s knit fabric. You’ll also want a more stable knit for a tracksuit.

You want some stretch, but not something super stretchy. You don’t want your jacket hanging loose like a nice flowy skirt. 

If you want to upcycle non-conventional materials, you’ll have to consider that some of them are not washable. And you’ll want material that you can wash.

Imagine working out or running around in your tracksuit, and you find out you can’t wash it? 

Also, I used low heat while pressing seams because the material might distort or melt. 

Now, I’m telling you the inside and outside of this fabric were so soft, like heavenly soft. So, whether it’s meant to be worn or not, I was going to use it up!

Plus, we had no use for this fabric, so I thought I might as well upcycle it into something fun.

Final Thoughts

In all, I really like how this tracksuit jacket came out, but there’s bad news. Shortly after making it, the garment burned up in the California wildfires.

So it’s gone, along with many things, but I still have pictures. I put a lot of hard work into this project, and I still love it.

More Sewing Projects

I have many other related posts on my blog. You might want to check them out.

• Would you like some outerwear sewing tips for making great garments?

• I made a cardigan hoodie that’s fun to wear in the fall.  

• What about making a nice double-sided scarf to go with this jacket?

I’d love to hear all about your sewing journey!

Originally published: August 10, 2025