Sew Edgy Integrated Belt in Wide-Leg Trousers

I’m continuing my “sew edgy” work wardrobe with some wide-leg trousers that incorporate a cool integrated belt thingy to add a bit of metal and polish.

The pattern is Simplicity 3688, a retro 1940s pattern whose cover model is a dead ringer for ass-kicking Lauren Bacall:


I have made these pants before in black denim. I wear them pretty often, but the pattern was really meant for fabric with more drape. This project is using a dark gray linen-rayon blend.

I wanted to modernize these a bit with an integrated belt copied from some RTW Karen Millen pants:

A built-in belt? Yes please!

This kind of built-in belt is a great option for me, to handle the whole waist-to-hip ratio without the need for an actual belt, which can get bulky and tends to ride up. Here’s how I did it, in case you want to try this at home.

This pattern has a side zip, not a front fly zip, so I wanted to add seams along the front for the belt pieces to sit into. Also, this trouser pattern has a straight, fold-over waistband because it sits high up. If you have a curved waistband or a waistband with a facing, you’ll need to do more tricky changes. (And I have no idea what those might be, sorry.)

Start with the original waistband, all marked with center front and back, side seams, buttonhole and whatnot. Interface it – I used sew-in interfacing because that’s what I had on hand.

Then figure out where you want to add seams for the integrated belt and mark them (straight lines in this picture):

Original waistband

I used the center-front marking to place the belt seams an equal distance away. Cut the waistband along those lines so the waistband is in three pieces.

Waistband cut to add seams

Cut a new center-front waistband panel, 2 inches longer than the original to allow for 1/2 inch seam allowances on either side. I am not adding seam allowances to the other waistband pieces, so the center panel needs to have enough runway on its own. Use your center-front marking to be sure it all lines up.

Add seam allowances and cut a new center front panel

Then make the belts. Because this waistband is a bit skinny, my belt is a bit skinnier than the RTW example. I made two belts – a short one to hold the D-rings and a long one to wrap across the waist, through the rings, and hang down a bit.

I just eyeballed the measurements here, based on the Karen Millen pants. The long belt piece I cut about 16 inches and the short piece about 3 inches, both 2 inches wide, including a 1/4 inch seam allowance, to get a belt about 3/4 inch wide.

I interfaced the belt pieces too, using fusible this time because the pieces are pretty small. I sewed them as two tubes and turned them out. The long one was a bitch to turn out, just FYI.


I put the two D rings in the short loop, folded it over and basted it closed.

Then I sewed up the the waistband with the new center-front panel, with the belt pieces attached in the seams, and pressed the seams open. The belt will sit in the center of the waistband once it’s folded over and sewn onto the trousers. Be sure to check the seam allowances here – this pattern has 5/8 inch where the trousers attach to the trousers and 3/8 inch on the facing side.


Completed in-seam belt

Ta da! Now I just need to finish the pants…

Author: shoes15

I live in Connecticut, USA with my husband and my dog, in an old house outfitted with a sewing room, a garden, an orchard, and a big liquor cabinet.

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