If you’re making the Frida Shirt sewing pattern, you’ll notice a lovely box pleat on the back of the shirt. This is a classic detail on traditional shirts, creating a relaxed silhouette with a little extra room for movement.
In this tutorial, we’ll show you how to sew the Frida shirt box pleat neatly and accurately. It’s a simple step once you understand the folding order, and it makes a big difference to how the back of the shirt sits.
What is a box pleat?
A box pleat is created when two folds of fabric are stitched and pressed toward each other on the wrong side (or inside) of the garment. Not to be confused with an inverted box pleat, where two folds are pressed towards each other on the right side (or outside) of the garment.
On shirts, a box pleat:
- Adds ease across the upper back
- Improves comfort and movement
- Creates a traditional tailored finish
In the below video extract from our online workshop Learn to Sew a Classic Shirt (featuring the Frida shirt sewing pattern), Tilly demonstrates exactly how to fold, press and stitch the pleat so it stays crisp, neat and centred.
Step 1: Mark the pleat lines
Your pattern includes two pairs of pleat lines, marked near the top of the back bodice (along the yoke seam).
Transfer these lines accurately to the wrong side of your fabric. Precision here makes all the difference.
Step 2: Fold and pin the pleats
Working on the wrong side:
- Fold the fabric right sides together to bring one pair of pleat lines together.
- Pin exactly along the marked lines.
- Check both sides to ensure the pin sits precisely on the marked line - adjust if needed.
Repeat for the second pair of pleat lines.
Step 3: Stitch the pleats in place
Take the fabric to your sewing machine.
- Stitch along each short marked line, back tacking at both ends.
- If needed, lower the needle into position using the handwheel before starting.
These short lines anchor the pleats at the top.
Step 4: Press towards the centre
Move to the ironing board.
From the wrong side:
- Press both pleats towards the centre back.
- On the Frida pattern, they won’t reach the exact centre back notch - there should be a gap between them.
- Pin in place if they don’t stay flat after pressing.
Good pressing gives a professional finish - you'll thank yourself later!
Step 5: Tack across the top
To secure the pleats before attaching the yoke:
- Set your machine to a long stitch length (4–5).
- Tack (baste) horizontally across the pleats, about 10mm (3/8in) from the raw edge.
This line of tacking holds everything neatly in place for the next construction step.
And that’s your box pleat complete!
Taking a moment to press the folds carefully will help the pleat sit beautifully on the back of your Frida Shirt, giving the shirt its relaxed shape and showcasing that classic shirtmaking detail.
If you’d like extra guidance while sewing your Frida shirt, our Learn to Sew a Classic Shirt online workshop walks you through every step of the process – from choosing your size and making fitting adjustments, to sewing details like collars, cuffs, plackets and more.
The workshop includes the Frida sewing pattern and step-by-step video lessons, so you can sew along with confidence and build your shirtmaking skills as you go.
