27 October 2021

How To Make Your Own Period Underwear! Part 1: Fabric & Alterations

How To Make Your Own Period Underwear

Period knickers convert? Fancy making your own eco-friendly pants for that time of the month?

 Following lots of requests, we're going to show you how to DIY your own period pants using the Iris knickers sewing pattern, thanks to this guest post by the pattern's designer, Hannah of Evie La Lùve. If you'd like to learn more about making your own underwear, Hannah teaches our online video workshop Learn to Sew Knickers, with video lessons packed full of tips and tricks. 

Over to Hannah!

Period pants have become increasingly popular over the last few years and while they may look like they require some magic fabrics and specialised equipment to make them, it is possible to DIY them! Making them yourself means you can create something tailored to your needs, whether that’s wanting to completely replace your disposable products for a more eco-friendly option, to use doubled up with a menstrual cup or tampons or for some comfy knickers to wear on those ‘due on’ days.

How To Make Your Own Period Underwear

The Iris knickers sewing pattern is perfect for adapting into period pants, especially as you can choose your leg and waist heights to suit the coverage you want. You’ll need to use FOE to finish the leg openings but a narrow stretch lace trim can still be used for the waist opening, which you may find more comfortable, particularly with the aches and pains that go along with periods for a lot of us!

So how do they work? These period pants have two additional layers of specialised fabrics that sit between the lining and main fabric at the crotch area. They’re designed to wick moisture away from your body, absorb it and then stop it leaking through to the outside of your knickers and beyond.

Choosing your fabric

Choosing your fabric

The first new fabric you will need is your absorbent material. There are a few options for this. I’m using a quilted bamboo ZorbⓇ but you can also use cotton ZorbⓇ, bamboo/cotton/hemp fleece or microfibre/bamboo/cotton terry towelling.

fabric examples

The second new fabric you will need is your waterproof material. You need a polyurethane laminated fabric, often referred to as a ‘PUL’ fabric. I’m using a bamboo fleece PUL material, which on the front (if you look closely) looks like a soft plush bamboo fleece, and on the back looks like it has a layer of clingfilm adhered to it. This is the waterproof barrier that will stop moisture from leaking out. 

The fabrics shown here were all purchased from Cuddle Plush Fabrics who have lots of choices for your absorbent and waterproof layers.

You may want to substitute your crotch lining fabric with a moisture-wicking jersey mesh fabric but that is optional, and use the wider of the recommended FOE widths (in the pattern instructions) for more sturdy leg openings. I’m using a 15mm (5/8in) width here though, which also works well

For your main fabric, use a fabric recommended in the pattern instructions. I’m using a cotton spandex jersey for this tutorial which works great!

Preparing your fabrics

Pre-wash your materials before cutting into them. If you’re using a quilted material that has loose fibres between the layers, like the one I’m using here, sew a small zigzag stitch (or you can use an overlocker if you’d prefer) around the edges of the fabric before washing, as this will stop the fibres from escaping in the wash. Don’t use a fabric softener when you pre-wash your materials or when you wash your finished knickers, as this will affect the absorbency of your materials. Hang them to dry and no tumble drying!

Pattern alterations

The Iris knickers have a ‘floating’ front edge to the crotch lining and the back crotch seam allowances are hidden between the lining and main fabric. For these types of knickers, you need to fully enclose all your seam allowances so that they're hidden away on the inside at the front too. This is to contain the extra layers of fabric as well as moisture. You may have come across this alteration in the Learn To Sew Knickers online workshop and the theory is the same here, though it looks slightly different.Iris knickers sewing pattern alterations

Take the front and back pattern pieces, and overlap the pattern pieces at the back crotch seam by 1 cm (3/8in) (this removes the seam allowance from the equation) and tape them together. 

alterations demoFirst, you need to add the front crotch seam. How long you make this is a personal preference but I recommend adding at least 2.5cm (1in) to the regular crotch lining length - you can use the notch along the leg opening as a guide. Remember… the larger the crotch area you create, the more moisture they can absorb. 

Mark the point on the centre front and draw a curved line to the leg opening. Make sure the line meets the centre front at a 90° angle, so it creates a nice smooth curve when it’s cut on the fold.

alterations demoYou may also want to move the back crotch seam further back so the absorbent area is larger. This is optional but something you may want to consider for heavier days or wearing at night. Do this in exactly the same way as you have for the front. You can keep the curve at an even distance from the existing back crotch seam, or create your own curve. 
alterations demoThe absorbent layer won’t be the full width of the pattern at the crotch area as it will be cut narrower. So to compensate, you will need to add width to the crotch pattern piece. Add some pattern paper behind this area and add at least 1cm (3/8in) along the crotch, tapering it into the leg opening so it’s still a smooth curve. You can add more width here if you’d prefer.
alterations demoTrace over the new crotch shape. Trim 3mm (1/8in) from the front and back crotch edges and 7mm (1/4in) from the leg opening. Fold the new crotch pattern piece along the centre front and cut it out to create the full pattern piece. This is the pattern piece you will use to cut out your absorbent material. It’s too bulky to be sewn into the seams and can be really tricky to finish the leg openings will FOE. Not to mention if the absorbent layer reaches the FOE, moisture can travel around the waterproof layer to the front through the FOE, which we want to avoid!
alterations demoCut along your new seam lines and add 1cm (3/8in) seam allowances to the new front crotch seam and the new back crotch seam as well as the front and back edge of the crotch pattern piece. 

Note: The crotch pattern piece is easiest to use when you have the whole pattern piece rather than half cut on the fold. So trace it off and cut it out folded along the centre front to create the full pattern piece.

If you haven’t altered the back crotch seam, add 5mm (1/4in) to the back crotch seam on the crotch and back pattern pieces. Usually, the seams here are 5mm (1/4in) but as there are a lot of layers to sew, making your seam allowances 1cm (3/8in) instead means they are less fiddly to work with.
alterations demoLabel your new pattern pieces. With the crotch pattern piece you’ve added seam allowances to you now need to cut: 
  • 1 x lining
  • 1 x main 
  • 1 x waterproof material
For your new crotch pattern piece (the smaller one) you need to cut 1 x absorbent material.

Period underwear flat-lay and scissors

With your pattern altered and your fabric ready, that wraps up part one of our DIY period knickers tutorial! It's time to start sewing your knickers, so head on over to part 2 to continue...

View 'Iris Knickers Period Pants Hack! Part 2: Cutting Your Fabric & Sewing'


If this blog post has inspired you to sew your own knickers, then look no further than our online workshop Learn to Sew Knickers taught by the Iris knicker's designer, Hannah of Evie La Lùve - with video lessons packed full of tips and tricks for sewing your own underwear, so you can fill your drawers with handmade drawers! 

Take our online workshop from the comfort of your home, revisiting the lessons as much as you need, whenever you want. Not only does Hannah take you through every step of sewing your Iris knickers, including shopping for supplies and picking your size, but she also shares how to hack your sewing pattern with bonus pattern pieces & more. Once you've made one pair, you'll be hooked!

Sign up today and learn to sew your own knickers!


Author: Hannah Bullivant

Learn to sew knickers