The Upholstery Forum

Hi everyone!
I’m learning how to upholster motorcycle seats, primarily in leather.
I’m stuck on how to account for adding skrim foam when it comes to my leather measurements..
The skrim foam I’m using is 1/2”.
The seat cushion has a U shape to the topside of it. (High front and back w a valley in the centre)
I’ve used a fabric tape to measure 25” for my piece (front to back) but after adding the skrim foam, the piece of leather is too short.
How much do I add to account for the 1/2” skim foam to get the length of leather I need? Is there a formula for this?

Thank you in advance!

Dumb question and don't be insulted but I assume you followed the shape of the seat and didn't measure straight across? Next, since I'm new to sewing, I made up a sample before hand out of some cheap vinyl I had on hand. I found it very helpful in both dimensions and actual sewing. I know leather sews different than vinyl but it should be close enough for testing.

I measured front to back. As mentioned, it is a U shape. The middle panel accounts for the full length (from base: up the front, over the top side, down and through the middle, up the back and down, back to the base). I’m hoping for an experienced seamstress or upholster to weigh in; I’m well versed in sewing, beginner upholster.

Maybe try cutting the foam to size or a bit larger and cut the leather to fit that. Then make a poster board pattern to correct size, add your seam allowance to that.