• No Products in the Cart

Minimum Stretch in Underwear


Undies are one of the easiest garments to sew (don’t ask me to call them panties, because I won’t). Streamlining construction, I combine the front and the back pieces at the crotch, so the only seams to sew are the side seams. Easy to make, yes, but I need more hands and fingers to tell you the number of times I’ve made a pair, but couldn’t fit them over my hips. That’s until I learned about minimum stretch.

Working as an assistant in the technical design department, knits category, a big chunk of my time was spent flat measuring. Laying a garment flat on a table, I measured front body length, back body length, armhole depth, sweep, etc. One of the measurements I took was minimum stretch, and it was probably the most important spec I recorded. In a woven, closures such as zippers, buttons and plackets ensure that a customer can get in and out of a garment, but in a knit, you have to make sure that the garment can stretch enough so a customer can put his or her head, hips, hand or foot through the opening (that’s assuming it doesn’t have a closure). An example is a long-sleeve knit tee – one of the minimum stretch specs (there might be several in one garment) would be at the sleeve opening, and it would make sure a customer’s hand can get through. If the garment doesn’t meet spec, the pattern must be adjusted (or garments resewn) before it goes to production. No way, no how would any retailer allow a style to hit stores that a customer couldn’t wear. This is what I was missing in my undie makings.

In an undie, the minimum stretch spec would be at the waist, and two factors affect it – fabric and elastic. If you want to wear that pair of undies you’re making, you have to make sure both the fabric and the elastic stretch to the largest part of your bottom half – your hips. How do you find this out? Let’s take my current, WIP pair as an example. The widest part of my hips measures 33 1/2″ (yes, I’m straight as a board from waist to hip), so I had to make sure that the waist opening, which measured 11″ flat, stretched to at least 17″ (which is the flat measurement of my hips: 33 1/2″ divided by 2). So, I cut a rectangular piece of my intended fabric and marked 11″ in the center (don’t mark at the edge – it’s not an accurate place to take this kind of measurement). I then stretched it to see if it would extend to 17.” It didn’t, so I increased to 12,” and it still didn’t meet the requirement. Thirteen ended up being the magic number, which meant I had to slash straight from waist to leg opening and open the pattern 2″ on front and back as shown below (you’re pattern will be on the half, but the diagram shows a whole pattern for clarity). Once I made sure the fabric suited my pattern, I used the same method to test my elastic.

Because every fabric and elastic stretches differently, you have to test with every pair you make. Have you heard a lingerie maker express how important fabric is to fit? Well, it’s true!


I hope this gives struggling lingerie makers out there some help. I know I was frustrated when I couldn’t figure out what was going wrong and threw a ton of undies in the trash. So sad to see lace in such a place!


  1. Reply

    The Nerdy Seamstress

    Thanks for this Maddie! I’ve been in dire need to make myself some new undies, but I’ve been scared to make them. Learning about this puts me more at ease to make my own undies. I don’t like the sound of panties either.

  2. Reply


    Fabulous! Thanks for sharing this!

  3. Reply

    Natasha Estrada

    I think undies is a much ruder word than panties. imho

  4. Reply


    Yes to undies! I also refuse to say the p-word. And thanks for sharing – I learned about minimum stretch the hard way when I was making a pair of pants that didn’t fit over my foot (without a fight, anyway) thanks to changing fabrics!

  5. Reply


    Great article – I’m a novice sewer and had never heard this term before, but have experienced the result of not knowing about it!! I have to say, being an Australian, UNDIES is the way to go … panties are what dirty old men keep in their drawer… undies are what we wear to be comfy and lovely 😀

    • Reply

      Maddie Flanigan

      someone shares my sentiments. thank you!

  6. Reply

    Gwen Gyldenege

    This is really interesting and most helpful. I’m curious – when you slashed waist to leg and added at the leg, didn’t you also change the leg hole shape and final dimensions? Did that work out in your favor (as in did you have leg holes too small for your fabric/elastic choice too?)?

    • Reply

      Maddie Flanigan

      Because undies are made with knit (or a combination or woven and knit), the circumference measurement at the waist and the leg opening are smaller than your bodies actual measurement. So, even increasing it by 1″ had no major effect on the fit of the leg opening.

      • Reply

        Gwen Gyldenege

        Thanks Maddie!

  7. Reply

    Jennifer Sauer

    Am i wrong in projecting this to other projects where perhaps you chose the wrong knit for the pattern? So, for instance, I could take the flat measurement of a given part of the pattern and “slash” in order to adjust the fit? Even if I’m wrong, this is excellent info you’ve shared. Thanks!

    • Reply

      Maddie Flanigan

      You are not wrong in your statement at all! I wouldn’t say the fabric was “wrong;” this tutorial is about making the pattern work for your fabric. Sure, I could have chosen/bought a stretchier knit, lycra or lace, but I wanted to use that fabric, so I made the pattern work for it. Does that make sense?

      • Reply

        Jennifer Sauer

        Perfect sense. I’m always finding fabric I want to use for a certain pattern and then I agonize because it’s not a “suggested” fabric for the design. I’m SO rules governed – hahahahahahaha!

  8. Reply

    Helen McFadyen

    Thanks for this. As Jennifer mentioned, this will be useful for all sorts of makes. And being British, pants or knickers works for me! Much simpler! 🙂

  9. Reply

    Beth – Sew DIY

    This is very helpful! I’ve had undies on my to-make list for ages now. Now I’ll know to check the stretch before I cut. 🙂

Leave a Reply