How to Replace bumGenius 4.0 Leg Elastic

bumGenius Leg Elastic

Replacing the leg elastic in bumGenius 4.0 diapers is super easy and helps you get more wear out of your diapers. Most of our 4.0s were purchased before the birth of our second son over 2 years ago and have been worn and washed many times. Being worn by toddlers, repeated washings and age caused the leg elastic to relax and it was time to replace the leg elastic in preparation for the arrival of baby #3!

The bumGenius 4.0 diaper is my favorite diaper, which is why my diaper stash primarily consists of them. We do have several bumGenius 3.0s that are nearly 4 years old, have been worn by 2 babies and have already had the leg elastic replaced.

Replacing the leg elastic in the bumGenius 4.0 is simple since they are designed for easy leg elastic repair. (This is not the case for the 3.0s, the leg casings are completely, making Β this process a little more difficult. I’ll be replacing the elastic in our 3.0s for the second time to get some more wear out of those diapers too).

Supplies Needed:


  • Elastic (1/4″ elastic, cut in 4.5″ strips)*
  • Needle
  • Thread
  • Scissors

*I purchased 1/4″ elastic which will cost me about $2 to replace all the elastic in my diapers.


Step 1 – Turn diaper inside out.
Step 2 – Locate one end of the elastic.
Step 3 -
Step 3 – Pull a bit of the existing elastic out of the seam.


Step 4 -
Step 4 – Take a new piece of elastic and sew onto the end of the existing elastic.
Step 5 -
Step 5 – Make sure your stitches are tight and the new elastic is secure on the old piece.
Step 6 -
Step 6 – Sew the opposite end of the new elastic onto the old elastic to prepare to pull it through the seam. Be sure this stitching is secure. You do not want the stitches to come apart while in the leg casing.
Step 7 -
Step 7 – Snip the old elastic near where the new piece is sewn on.
Step 8 -
Step 8 – Once the old elastic has been snipped, prepare to pull the new piece through the casing.
Step 9 -
Step 9 – Go to the opposite end and pull on the existing elastic which will pul the new elastic through the casing.
Step 10 -
Step 10 – The new elastic is through the casing and ready to be sewn on the other side.
Step 11 -
Step 11 – While holding onto the new elastic that has been pulled through (so it doesn’t fall back into the casing), snip off the end of the old elastic. Remove the stitches holding the new and old elastic together.
Step 12 -
Step 12 – It’s now time to sew the new elastic onto the small piece of old elastic.
Step 13 – Securely sew the new elastic onto the end of the old elastic.
Step 14 -
Step 14 – Once the new elastic is securely sewn onto the end of the old elastic, you’re finished! You’re replaced one side of the leg elastic!
One Side Replaced
The elastic on the left has been replaced while the right side is the old elastic. You can see the difference replacing the elastic makes.
Replaced Leg Elastic
This shows you the difference replacing the leg elastic can make. The diaper on the left just had the elastic replaced while the diaper on the right has not. Over time and after many wears and washes, the elastic relaxes and makes the diaper bigger. Replacing the leg elastic gives new life to your diapers and makes them able to fit small babies.

It takes me about 30 minutes to an hour, depending on distractions, to replace the elastic in each diaper. It is well worth the time to extend the life of our diapers.

Replacing the back elastic follows the same steps as the leg elastic. The back elastic tends to wear slower so you may not even need to replace it.

Once I finish replacing all of the elastic in our diapers, we’ll have like new diapers ready for our new baby and will only have spent $2!

These diapers have been well worth the investment, 10 of them are nearly 4 years old and the rest are over 2 years old. We haven’t had to purchase any cloth diapers at all for baby number 3 since the ones we already have are in such wonderful shape.

I hope this tutorial helps you replace the leg elastic in your diapers and extend their life!

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How to Replace bumGenius 4.0 Leg Elastic


responses to “How to Replace bumGenius 4.0 Leg Elastic” 57

  1. Thanks for the nice tutorial, our little girl is now 1 year old and I'm currently checking for some new Diaper ideas / brands. bumGenius looks interesting – I will give it a try.

  2. Wow. What providential timing! I literally wrote on my to do list for the day: "Google how to replace Bum Genius elastic", and then I check my email and see your post! Thank you so much for the clear tutorial πŸ™‚

    Also…I love the color of the diaper you used in the tutorial…do you happen to know what it is?

      1. Curious why you couldn’t just use a small safety pin to attach the two, eliminating a step that just gets snipped

  3. Such a smart and simple method! I've made all of our baby's diapers, but have done the elastic casing/topstitching in a way similar to the Bum Genius 4.0 to make for easy elastic replacement! πŸ™‚

      1. Thanks for this! I was able to replace the leg elastics. I need to replace the back for a couple of them. I can’t find the back elastic exposed in my 5.0 pockets like it is for the legs. Do I need to unstitch the fabric to find it?

    1. My replaced elastic has worn the same as the elastic in new diapers.

      I replaced leg elastic in my first baby's diapers before the birth of my second and also purchased new diapers. All of the elastic was ready to be replaced 2 years later in preparation for the birth of my third baby!

    1. It's the exact same, you just have to open up the front of the diaper first. The top seam above the snaps. So you might want matching thread to sew it back closed.

    1. In the bumGenius 4.0s, no seam ripping at all! In bumGenius 3.0s, Freetimes and Elementals/Organics, seams will need to be ripped out in order to replace the elastic.

  4. Thanks! Don't know WHERE I'll find the time to do this (I work full-time and have a 3yo) but it's on my list of needs before little mister shows up in January. I've got to go through my stash and replace the elastics on the well-worn dipes, so probably close to 20 will need it, but for two bucks – heck yeah! THANKS!

  5. Thank you SO much for this tutorial I cannot express how easy and simple this is (even for me)! I not only "freshened up" my remaining BGs but now I am happy knowing I can buy some well-loved diapers and keep them lovable for my new baby coming next summer. YAY! oh and just a sidenote, the elastic in the BGs is really small 5/8 in or smaller I think, and when replacing with 1/2 in elastic which is all I had on hand it can be a little tougher to pull through the tiny casing. BUT I did it and I think wider elastic will hold up longer this time and catch more poo. We'll see! Thanks again!

  6. Thanks for the tutorial! I just did this, using another tutorial, and ended up looking my old elastic inside the casing… do you by chance have any tips or ideas to get it out? Thank you!

    1. This JUST happened to me, I’m wondering if you (or anyone) ever figured this out?? I completed 3 successfully and have 12 more to complete and I’m feeling very discouraged

    1. I don't own any of the bumGenius newborns and have never replaced elastic in anything but the 4.0s. Send Cotton Babies an e-mail asking the length, they typically have excellent customer service and I'm sure they'll have that information for you.

  7. Hi ! I have been reading your blog for sometime, love it! So it takes you 30 minutes per diaper? Seems very time consuming but my mother in law just picked us up 15 used velcro bgs that desperately need new elastic so I guess I had better get to work! This tutorial is perfect. I know this post is old but I am also wondering if you have any advice for bumgenius diapers leaking out the legs? Our little one is a chunky 15 pounds and the diapers have been great for about 3 months but they seem to leak through the legs around her bum constantly now .. to the point where she needs a clothing change sometimes 5 times a day !

    1. It is a bit time consuming but I love that I am able to spend a bit of time and make them useful! For the leaking, it is possible she is a heavy wetter and you simply need to add a doubler in. Hopefully that will fix the issue! Some of my older diapers started leaking around the legs during every wear and the PUL was just bad. πŸ™

      1. Thanks ! Unfortunately sometimes they aren’t even really wet when they leak and other times they are .. but they are new as of 4 months ago so I really hope it isn’t a pul issue! And it is a very inconsistent issue, some days it is all the time and others hardly at all! And I’m starting to notice specific diapers as well … thanks for the advice! πŸ™‚ πŸ™‚

  8. One more question! Did you use braided or knitted elastic? My husband picked some up for me and it is knitted, while many tutorials state braided

  9. I just finished one diaper and I’m thrilled! BUT, the second diaper I was working on, 2nd side, the stitches came undone, like you warned, as I was pulling through πŸ™ what can I do?

    1. This happened to me. I looped a safety pin through the new elastic and just worked it through the casing, slowly but eventually we got it!

  10. Thank you so much for this wonderful tutorial, it has saved me twice now. I've only done three of my worst diapers but I don't consider myself able to sew at all and I did it no problem!

  11. I'm currently pregnant with baby number 2. our first is 21 months and about 28 pounds. I use the bumgenius 4.0 diaper. My question for you is, how long do you use the diapers for? Are you able to use them until potty training. I know the diaper says you can use it between 35-40 pounds so wondering if anyone else has any other experience on this. Will my toddler be able to wear these until we potty train?

    1. I’m sure you’ve figured this or by now, but yes! My 3.5 yo (now 5yo) boy wore them when he was potty training no problem.

  12. How long should the new elastics be? Do you ha e a sizing chart? I have a bunch of the Velcro sized aio bumgenius that need legs and or backs replaced. I cannot find a chart or get a reply from them on how long the new elastics should be.

  13. How long should the new elastics be? Do you have a sizing chart? I have a bunch of the Velcro sized aio bumgenius that need legs and or backs replaced. I cannot find a chart or get a reply from them on how long the new elastics should be.

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