15mm. I never knew this tiny measurement would become such a key part of my life. But it’s the standard seam allowance in most sewing patterns and now I can eyeball 15mm with impressive accuracy.
It’s not always clever or wise to eyeball, so sometimes I use measuring tools. Get me! If I don’t have a measuring tool, I use my thumb. From thumb tip to the base of my nail is about 15mm. (That’s how long my thumb is. You should measure first if you want to sew by your own rule of thumb.)
I’ve heard that the tip of a tape measure is the equivalent of 15mm, but not in this house. I checked. That’s the type of detail that could really impact on sizing.
I’d also be cautious around the accurate readings from retractable tape measures. They can stretch.
If you’re lucky, your sewing machine will have seam allowances marked on the throat plate. If yours doesn’t, you can always add a strip of masking tape. Gawd bless masking tape – so many functions. (It’s also great for when you’re pinching out or repairing paper patterns as it can be removed easily and doesn’t melt under an iron.)
Once upon a time, I cared about a 24-inch waist. (I mean, I never had one. I just cared about never having one.)
Now, all I care about is 15mm.