SAAS (Sewing at Any Size): Basic Panties/Swimsuit Bottom

SAAS: Sewing at Any Size : Basic Panties or Swimsuit Bottom

This is my series on Sewing at Any Size, a protest against overpriced, badly constructed and badly-fitted clothing options available to anyone who isn’t shaped like a fit model.

You can see the rest of the SAAS series by clicking on the category link on the sidebar. As this will eventually become a book, please do not re-publish or re-post this material. Feel free to link to it however, or print/save for your own personal use.

Whether you’re plus size and sick of paying too much for badly-constructed underwear, or non-plus size and want to express your artistic side, the panty is the perfect place to start. We’ll start with the absolute basic panty shape, then play with alternatives (bikini, boy shorts, thong, etc.) in future posts.

The easiest way to create a pattern for panties without a single measurement is to sacrifice an existing pair. Pick apart the side seams and lay it flat. Trace it onto a piece of sturdy fabric or paper so that you have a permanent pattern for the future. You may then be able to stitch the panties back together if you’re really attached to them.

When choosing your fabric, your options are limitless as long as it’s stretch. You will also need a small piece of coordinating tee-shirt material (check the remnant bin) to sew into the crotch as a pantyliner. This is optional of course. If you’re making this into the bottom of a two-piece swimsuit, use lycra blend swimsuit material for the main piece and both the binding and liner. You can use other materials, of course, but they may not react well to continued soakings or hold the shape when wet. If you’re making a swimsuit out of non-traditional swimsuit material, test the effects of chlorine on the fabric by washing a scrap in bleach.

If you really, really want to start from scratch on the panties, start with measurements:

Measure around your hips where you want the waistband to be. Divide this number by two. We’ll call this measurement “A”.

Measure around your upper thigh right where it meets the leg. We’ll call this measurement “B”.

Decide how far above the top of the leg you want the waistband to be. For high waisted panties this will be a larger number, for low waisted it will be smaller. We’ll call this measurement “C”.

Decide how wide you want the crotch to be. This is a good time to measure an existing pair of panties! Divide the number by two. We’ll call this measurement “D”.


We’ll start by making a pattern out of scrap fabric. You can also use a piece of brown paper bag for this, since the test pattern will be relatively small. Since you want the shape of the panties to be symmetrical, start by folding your scrap fabric in half.

Trace the approximate shape below (red lines) with the dotted line on the fold of the fabric.


Now the reason why you’re using test fabric or paper is that this shape will not be perfect! Cut it out and unfold it. Try it on (holding the sides together at “C”). Remember that we don’t have any seam or hem allowances yet, so it should fit exactly. Adjust the shape as needed to fit the way you want. If it needs to be smaller or narrower, cut away until you like it. If it needs to be larger, approximate how much and cut a new piece from your test fabric (if you’re using paper you may just be able to cut pieces and tape them on to expand areas instead of cutting a whole new piece.)

Once you like the shape, you have a pattern! You can continue to construct a practice pair out of your test fabric by applying the following instructions (recommended), or jump straight to your final fabric.

Trace your pattern onto your fabric.

Add ¼” to each edge that had the measurement “C” (the ones that will become the sides.) Use a pencil, chalk, or water-soluble marking pen (you can get them from the craft or fabric store).

When you cut out the shape, include the ¼” seam allowance you just created. The lines to cut are in red dots in the figure below.


We’re going to use stretch binding to finish the panties. You can also use ½” wide lightweight elastic, folding it over the edge like regular binding. If the original fabric you used has a good firm stretch, you can use a piece of it as binding.

See this post for instructions on how to use binding!

Stretch fabric, elastic and binding are notoriously hard to work with on a sewing machine, especially when dealing with tiny measurements like these. You want to use something to stabilize the fabric while you work with it to keep it from getting sucked down under your foot plate and ruined.

The ideal stabilizer for this project is probably lightweight tissue paper. I don’t mean kleenex or TP, I mean the stuff you use in art class or stuff into the top of gift bags. This is available at craft stores and card stores, or you can save it from past gifts. Place it between the fabric and the footplate as you sew, then tear it out later. Remaining scraps should come out when you wash it, or you can pick it out fairly easily.

If you choose to use a panty liner, cut a piece of tee-shirt or other lightweight jersey the width of the crotch and approximately half the length. Hem the top and bottom ends, and sandwich the sides into the binding along with the fabric of the main panty.



Sew binding along the top and bottom edges of the panty, and along the curves that will be the leg holes (red dotted lines below). If you added a liner, make sure the binding captures both layers of fabric. Make sure you place a layer of tissue paper under the fabric as you sew.


Fold the panty up with the right side together (the side you want to show while wearing it). Stitch the sides together, leaving a ¼” seam allowance.



If the fabric you use doesn’t unravel or shred when it’s stretched, you can simple trim the seam to where you want it and be done. If it does, add a strip of zig-zag stitches to secure it (or overlock if you have it available). Trim the fabric back to the stitches.

At this point you have a very basic pair of finished panties or a swimsuit bottom. In future posts we’ll go into variations on cut, assembly and decoration.