The machine sews forward two stitches, back one, forward two — so every part of the seam line carries three passes of thread. On the dial it is usually drawn as a straight line with a thickened look, sometimes labelled a stretch straight stitch.
What it is for.
Seams under real strain — crotch seams, armholes on workwear, bag handles, anything that takes load rather than just holding two pieces together.
Fabric with a little give, where a plain straight stitch snaps. The back-and-forth motion gives the seam a small amount of elasticity, which is why some manuals call it a stretch stitch.
Heavy topstitching where you want a thicker line without changing to topstitch thread.
The costs, and they are real. It uses three times the thread. It sews slowly. It is very difficult to unpick — you are cutting three passes rather than one, and on fine fabric you will damage the cloth before you get the stitches out. And it builds bulk, so it is wrong on lightweight fabric.
Use it deliberately, not by default. A garment sewn entirely in triple stitch is stiff, heavy and effectively unalterable.
Settings. Length is preset on many machines; where it is adjustable, around 2.5 mm. Use a needle appropriate to the fabric, because the needle passes through the same holes repeatedly and a blunt one will damage them.
Test it first on a scrap, including a test of unpicking it.
Questions people actually ask
Is it the same as a stretch stitch?
Some manuals use the terms interchangeably. The lightning-bolt stretch stitch is a different shape — triple stitch is a reinforced straight line, not a narrow zigzag.
How do I unpick it?
Slowly, cutting from one side only, a few stitches at a time. Which is the argument for testing on a scrap before committing to a garment.
Last reviewed 2026-08-11