How to Sew Your Own Underwear + FREE Pattern!

My dear friends today I want to introduce you to my newest pattern the Acacia underwear! Have you ever wanted to sew your own underwear? This pattern is my gift to you as a thank you for following along with me, being a part of this sewing community and supporting my brand the whole year. You make it possible for me to do what I love, and you inspire me to make more and do better every day. I really hope you enjoy sewing the Acacia underwear pattern as much as i enjoyed making it for you!

If you follow my newsletter you will have already received an email about Acacia with details on how you can download this pattern for free. If you aren’t yet on my newsletter, you can sign up here and download instructions will be emailed to you.

I started working on this sewing pattern the same way all my patterns start. I was unhappy with all of my store bought underwear, and wanted to make my own but I couldn’t find a sewing pattern that had the fit I wanted. Don’t get me wrong, I love lace underthings as much as the next girl, but what I really wanted was something basic and normal and super comfortable that I could wear every single day and fill up my dresser with. I wanted enough bottom coverage that my life would be a wedgie free zone, because you guys! – I refuse to put up with that.

So I put all of the things on my undie wish list into this pattern! Acacia has a low rise (but not super low), and a comfortable leg cut with ample coverage. The gusset has fully enclosed seams because no-one needs their undies to include a built in lint trap pocket. I’ve also include three methods for attaching your elastic, because we all need options! And you know what, if you want to sew these out of stretch lace – you still can!

Also they are so easy and so fast to sew up, perfect for beginners to learn some new skills or for experienced sewers to whip up a pile of.

I wanted it to be easy to make this pattern out of your scraps, so all of the pattern pieces are full size (as opposed to the usual “on the fold” style) so that it’s easier to squeeze them in on your fabric scraps. It’s like underpants for free! Can you tell i’m excited?

Though the pattern comes with detailed instructions and sewing diagrams, I know that many of us also like seeing photos of how to make things in more detail, so I’m going to show you how to sew these from beginning to end using all three elastic attachment methods.

Ready to sew?! Lets do this!

First thing you need to do is gather up some fabric or some scraps, as well as your chosen elastic. Your fabric should have at least 20% stretch and good recovery. The last thing you want is for your undergarments to stretch out while you are sewing, or be too small when you try them on, so please make sure you check the stretch and recovery before cutting.

Also given that the fit of underwear is often a very personal preference, i recommend that you absolutely make a test pair before cutting into your favourite fabric. This will allow you to decide whether you like the fit as is, or whether you need to make changes. This is also a good time to decide if you like the tightness of the elastic or whether you need to adjust that too.

Keep in mind that elastics like fabrics can vary in stretch and recovery and stability, so you may find that you need to make adjustments with some elastic kinds and not others.

This pattern includes instructions for three kinds of elastic: regular 1/4″ (6mm) wide elastic, picot lingerie elastic, and fold over elastic. You can also use stretch lace as above, and this will simply be applied flat over the seam and topstitched with a zig zag stitch.

The white picot elastic on the very left has really terrible recovery, and I found that the pair i made using that elastic are not as comfortable as all my other pairs as the elastic gets significantly looser as the day progresses. Just a cautionary tale for you, because i know you gals love that hehe.

For each pair of undies you will need to cut one Front [1], one Back [2], two Gussets [3] and three pieces of elastic. One Gusset will be the internal Gusset and the other will be the external Gusset. To make my tutorial clear I have used a contrast fabric for all internal Gussets so that you can always tell what is the right or wrong side of my garment.

The elastic measurements are included in the pattern. One piece will be for the waistline, and the other two will be the leg openings.

// HOW TO CONSTRUCT BASIC UNDERPANTS WITH ENCLOSED GUSSET //

Place one Gusset [3] (the external Gusset) right sides together on the Front [1] so that the crotch seams are aligned.

Sew ¼” (6mm) from the raw edge using an overlocker/serger or zig zag stitch or pin in place for now.

Open flat.

Place the Back [2] on the Gusset [3] with right sides together, ensuring that the notches are aligned.

Sew ¼” (6mm) from the raw edge using using an overlocker/serger or zig zag stitch, or pin in place for now.

Roll up the Front [1] and Back [2] and pin them so that they are out of the way.

Place the second Gusset [3] (the internal Gusset) right sides together on top so that the crotch seams line up and the front and back are sandwiched between the two gussets.

Sew the front and back crotch seams ¼” (6mm) from the raw edge using an overlocker/serger or zig zag stitch.

Pull the Front and Back pieces through the Gusset, turning the underwear right side out.

Press the seams flat.

Line up the side seams with right sides together.

Sew ¼” (6mm) from the raw edges using an overlocker/serger or zig zag stitch.

Press the seams open or towards the back.

You are now ready to decide which method of elastic insertion you wish to use!

// HOW TO ATTACH REGULAR ELASTIC //

When using regular elastic we recommend using ¼” (6mm) wide elastic. For this sample I have used swimsuit lining as the internal Gusset. I have two kinds of 1/4″ elastic in my stash, and this one is the more stable with the best recovery. Make sure you check your elastic recovery as it will affect  your fit.

This method of elastic insertion will make it appear that the side seams are narrower than when using picot elastic. The reason for this is that when using picot elastic some of the elastic will extend beyond the garment edge. Though they look slightly different, both ways fit equally as well.

Overlap the edge of your elastic by ¼” (6mm) and pin or baste.

Divide all three pieces of elastic into quarters with pins.

Divide the waistline and leg openings into quarters and mark with pins.

Pin the elastic to the waistband and leg openings on the wrong side of the fabric, ensuring that you line up the quarter mark pins.

Sew the elastic to the waist and leg openings using a zig zag stitch and sewing directly through the centre of the elastic.

You will need to stretch your elastic as you sew so that the elastic and fabric are aligned.

Fold the elastic edge towards the inside of the underwear.

Sew along the raw edge to enclose the elastic using a zig zag stitch and once again stretching as you sew.

// HOW TO ATTACH PICOT ELASTIC //

This method will help you attach picot elastic which is the most widely used lingerie elastic and generally has a scalloped or decorative edge.

Picot elastic has a right side and wrong side, which is usually pretty obvious when you look closely. The wrong side is usually flatter/smoother and has less detail.

When we sew the elastic to the garment it will be right sides together, so i recommend you figure out which side is the right side of your picot elastic befor sewing.

Overlap the edge of your elastic by ¼” (6mm) and baste or pin.

Divide all three pieces of elastic into quarters with pins.

Divide the waistline and leg openings into quarters and mark with pins.

Pin the elastic to the waistband and leg openings on the right side of the fabric, with right sides together, ensuring that you line up the quarter mark pins.

The picot edge should be pointing towards the garment, not away from it.

Sew the elastic to the waist and leg openings using a zig zag stitch and sewing directly through the centre of the elastic. Some people like to sew a little closer to the scallop edge so that only the decorative edge shows out the edge of the garment, but I prefer a little of the elastic showing too. Keep that in mind when you choose where to sew.

You will need to stretch your elastic as you sew so that the elastic and fabric are aligned.

Fold the elastic towards the inside of the underwear. The picot edge will now point outwards away from the garment.

Sew along the raw edge to enclose the elastic using a zig zag stitch and once again stretching as you sew.

// HOW TO ATTACH FOLD OVER ELASTIC //

Fold over elastic has a plush side and a shiny side. Most people use the plush side as the right side, and the shiny side as the wrong side, however you may sew it the other way round if you wish. Fold over elastic has a line running down the centre that makes it easy to fold in half.

Using this method we will not be turning the fabric in by 1/4″ (6mm) along the waist and leg openings as with the other methods. This will result in the waistline sitting slightly higher and the leg openings extending further by a little. Personally, I find the fit is still really nice and not worth making any alterations, however if you prefer, you may trim 1/4″ (6mm) off the waist and leg opening edges before sewing the elastic so that the finished garment is closer to the other styles. I think this would be easier to do on the pattern pieces themselves before cutting out your fabric.

Place your fold over elastic right sides together and sew the edges together ¼” (6mm) from the raw edge.

Divide all three pieces of elastic into quarters with pins.

Divide the waistline and leg openings into quarters and mark with pins.

Pin the elastic to the waistband and leg openings, folding the elastic over the raw edge to encase the raw edge. I like to fold over and pin at the quarter marks only, and then as I am sewing i gently align the rest of the fabric and elastic as needed.

Make sure that your elastic seam is sewn with seams open as above to reduce bulk.

Sew the elastic to the waist and leg openings using a zig zag stitch and sewing directly through the centre of the elastic or along the edge as I did.

You will need to stretch your elastic as you sew so that the elastic and fabric are aligned.

That’s it! Now you can enjoy sewing yourself way too many pairs of undies in any fabric and elastic combination you would like! The options are really endless!

I hope you enjoy Acacia and can’t wait to see what you do with this pattern! Don’t forget to tag your creations with #MNacacia and @megannielsenpatterns when sharing on social media, and check out what everyone else is up to!

If you haven’t downloaded the pattern for FREE yet, just fill in your details below to subscribe to my newsletter and download details will be delivered right to your email! If you have any questions at all, please let me know in the comments!