August 18, 2022

How to adjust an underwear pattern, featuring the Radcliffe Undies!

This month’s Cashmerette Club pattern is the Radcliffe Undies, which features three rise heights and multiple leg and waist finishes. Today, we’re showing you how to adjust the Radcliffe by raising or lowering the leg height, raising or lowering the rise height, and more!

Thoughtfully designed for curves, the Radcliffe Undies pattern brings comfort and sexiness to your wardrobe in a neat little package. The Radcliffe features seamless sides, optional fabric or lace paneling, and three rise height options: high rise, mid-rise, and bikini rise.

With multiple leg and waist finish options, you can craft your perfect pair of undies from over a dozen possible combinations! This pattern comes in sizes 0-32 and is available exclusively to Cashmerette Club members.

Underwear fit is a very personal thing, and many of us are fairly particular about how we like our undies to fit. But the joy of sewing is that we can adjust a pattern exactly to our liking!

Start with a test pair of undies

The best way to determine what adjustments to make is by making a muslin and trying it on. Remember to use fabric that meets the stretch requirements of the pattern, and that is similar in weight and stretch to your final fabric. You should also use the same type of elastic that you’re planning on using on your final version—that’s the best way to get a feel for how your final undies will fit. Thankfully, undies are quick to sew and don’t use a ton of fabric, so you’ll be on your way to making your final undies in no time.

After trying on your undies muslin, keep reading to learn how to adjust the pattern.

Note: if you’re working with View A or B of the Radcliffe (with the contrast fabric or lace panels), you can start by taping the side front pattern piece to the center front (overlapping the seam allowances) and treat them as one piece when making your adjustment, then separate them back into two pieces.

How to raise or lower the leg height on an underwear pattern

Do you prefer the leg height to be higher or lower? This can be a style preference, but it can also be a matter of fit—some of us have a more angled line where our leg meets our torso, while others have a less angled line.

If you’d like to raise the height of the leg, determine how much higher you want it to be, then remove that length from the top of the leg opening on the front and back pieces, then curve it down to nothing lower down the leg opening, like so:

Conversely, if you want your leg height to be lower, you would add length at the side seam and curve back to nothing, like so:

Once you’ve adjusted your front and back pattern pieces, you can calculate the length of your new elastic by measuring around the leg openings at 1/4″ in from the raw edge and multiplying that by 80% for fold over elastic or 90% for picot elastic.

How to raise or lower the rise height on an underwear pattern

The Radcliffe Undies includes 3 rise height options: high rise, mid-rise, and bikini. You can choose the rise option that you most prefer!

But what if you want to raise or lower the height beyond the pattern? There are two different reasons why you may want to adjust the rise height, and they’re treated a bit differently.

If you’re adjusting the rise because you’re taller or shorter than the pattern is drafted for (we draft for 5′ 6″), you will want to add length in the middle of the rise. Here’s how to do that:

1. Draw a straight line that is perpendicular to the center fold line on the front pattern piece, approximately halfway between the bikini and mid-rise line:

2. Cut the pattern piece at that line, and slide it up or down by the amount that you want to add/remove. Then redraw the side seam and center line:

3. Repeat with the back pattern piece.

With this adjustment, you haven’t changed the length of the waist or leg edges, so you can use the same elastic measurements provided in the pattern.

Note: remember that the part of your body covered by the underwear is only a small portion of your total height. So if you are 5′ 3″, you don’t need to remove 3″ of height!

If you’re adjusting height of the rise not because of your height but because you prefer the look and feel of the waist at a different spot on your body, you would add or remove the length from the waist edge. Simply redraw the waist edge where you want it to be.

With this version of the adjustment, you are changing the length of the waist, so you’ll need to recalculate the length of the waist elastic. You can do so by measuring the waist opening at 1/4″ in from the raw edge and multiplying that by 80% for fold over elastic or 90% for picot elastic.

How to widen or narrow the crotch on an underwear pattern

If the width of the crotch is wider or narrower than you need, you can easily adjust the pattern to your width.

Once you’ve made you initial muslin determine just how much extra fabric you need through the crotch, you can add or remove that from the crotch, like so:

Once you’ve adjusted your front piece, you then need to modify your gusset piece in the same manner.

And then you’re good to go!

How to adjust an underwear pattern to use stretch lace trim

Included in the Radcliffe Undies are instructions on how to use fold over elastic or picot elastic on the legs and waist and two ways to use a wide elastic lace on the waistband. But what if you prefer to use a narrow stretch lace trim throughout? Easy peasy!

  1. Start by trimming 1/4″ off the leg edge and off the waistband of your pattern pieces.
  2. Cut your stretch lace trim to the lengths shown for the picot elastic. Join each in a circle (making sure it is not twisted) and sew ends together flat using a zigzag stitch or honeycomb stitch, reinforcing several times. Trim free ends close to the stitching line. 
  3. With the right side of the lace trim facing up, and wrong side of the lace trim against the right side of the undies, pin the trim around the leg opening and waist opening evenly, aligning the outer edge of the lace trim with the raw edge of the undies. The best way to do this is to divide the loop into quarters and mark, then match those marks with the notches.
  4. Using a 2.5mm length/2.5mm width zigzag stitch, sew the lace trim to the leg opening along the inner edge of the trim (the side closest to the undies).
  5. Finally, flip the undies inside out and trim the excess fabric behind the lace trim, going as close to the stitching line but not cutting into it.

Voila! You’ve got a beautiful pair of undies with stretch lace trim.

Want to sew your lace trim flat? Check out this tutorial from Bra-makers Supply.

We hope this tutorial helps you create your perfect pair of panties! If you’re ready to start sewing handmade lingerie, head over to the Cashmerette Club to get the Radcliffe Undies:

(Note: If you’re joining the Club after August 2022, you’ll need to join at the All Access level to get the Radcliffe Undies pattern.)

2 thoughts on “How to adjust an underwear pattern, featuring the Radcliffe Undies!

  1. Julie says:

    this is great – thanks so much for this pattern! a nice add-on hack pack for this would be how to turn this pattern into a pair of boy-short type undies. no need (ever) for a thong version, but boy shorts would be awesome!

    1. Cindy says:

      I agree! Boy shorts would be awesome!

Let me know what you think!