How to Sew Briefs and Boxer Briefs with Peek-a-Boo Patterns

How to Sew Briefs and Boxer Briefs

Today, we’ll share with you how to sew briefs and boxer briefs. We’ll be using the Classic Briefs and Boxer Briefs pattern from Peek-a-Boo Pattern Shop.

I won’t go through the patterns step by step – you can get most of that just by reading the pattern. Instead, I’m going to focus on tricky areas and questions that continue to arise about particular steps.  I’ll mainly focus on the fly, as that can be a little tricky the first time around.  I’ll also give you a tip towards the end on how to get those bands looking nicely when sewn!

How to Sew Briefs and How to Sew Boxer Briefs

Let’s get started!  We will work on the faux fly first.  Note that the construction of both fly options on boxers and boxer briefs are the same.  My pictures for the faux fly will be for the boxer briefs.  Your pieces should already be cut and marked.

Sewing a Faux Fly

Boxer Briefs with faux fly
Boxer Briefs with faux fly
Briefs with functional fly

Briefs with functional fly

Grab your Wonder Tape and your Front Panel.


Apply the Wonder Tape to the faux fly mark on the front panel.  Peel off the paper backing and then stick your binding onto the front panel.  You will have to stretch the binding slightly to fit around the curve.  The beauty of the Wonder Tape is that your fabric can be repositioned once on the tape!  Now head to your machine and topstitch along both long edges.  Once you topstitch, continue with construction as the pattern indicates.

Here’s a tip: Don’t skimp on topstitching!  Take your time!  Topstitching helps to tack the seam allowances down and will make the undies and socks more comfortable.  When working with knits, I sometimes use wooly nylon in my bobbin and in the loopers of my serger.  Wooly nylon is a soft, stretchy thread and makes the seams a little more comfortable.  But it’s not a necessity and my kids certainly wear lots of knits sewn with just regular thread!


Here’s another tip: Machines like to eat knits when they are close to the edge when starting to sew!  So, before you start your topstitching, make sure your bobbin thread is pulled through your machine, giving you a little tail to hold onto.  Position your fabric under the presser foot and grab the bobbin thread.  As you begin to sew, gently pull on that bobbin thread.  It will help the fabric to move under the presser foot without stretching your knit fabric.  If you were to pull on the fabric instead of the bobbin thread, then you’d end up with a wavy and stretched out mess.

Sewing a Functional Fly

Let’s work on the functional fly now.  My photos here will be of the Classic Briefs, but again, the construction is the same on the Boxer Briefs.  You can see how my Front panels are cut mirror image (or 1 right and 1 left).  I used two different fabrics to help distinguish the difference.  The grey solid will be the piece towards the inside of the briefs.  The print will be on the outside.


Attach and topstitch the binding pieces with the same tips I mentioned for the Boxer Briefs.  Once you sew the binding pieces onto each of the fly pieces, you’ll lay them on top of each other like this.  Baste these pieces together as indicated in the pattern and continue with construction.


Since I did the functional fly with the briefs, I used the enclosed seam method for the bands.  A tip here is to use your Wonder Tape!  Once you attach the band to the wrong side of the leg opening, apply the Wonder Tape to the outside and finger press the band evenly around the leg opening.  Take your time topstitching!

Get Those Bands Looking Nice

Here’s my secret to ensuring that my fabric won’t be wavy when attaching bands on knits.  This works for waistbands, leg/arm bands, and even neck bands.  I clip or pin my bands on and then turn the garment right side out.  This way, when I put it on my machine, the band will be underneath and the main fabric will be right side out on top.  

As I gently stretch the band to make it fit the opening, I can see if my main fabric is stretching since it’s right on top!  You only want the band to be stretched.  As I go around I let a little tension off of my stretch to make sure I’m only stretching the band and not the main fabric.  Again, take your time as you go around.  Getting bands on perfectly without having wavy seams takes practice!  A good steaming afterward will help also!


Here are my finished Boxer Briefs and Briefs!


For girl’s underwear, make sure to also check out my tutorial on How to Sew the Classic Panties and Camisole!

As always, make sure to come to join our Peek-a-Boo Pattern Shop Facebook Group to share what you’re making and get sewing assistance. Also, before, you leave, take a look at some of our other tutorials:

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