I'm Drawing a Blank on a Measurement....
 

If I have a 10 1/2" block and I want to sash two sides....One piece of sashing is going to be 10 1/2"...How long is the other, longer piece? (The bottom piece in the picture.)
I've been driving myself crazy with this.

Thanks! Watson

PS...the sashing is 2 1/2"

Depends on how wide the sashing is. Add that width to the length of the last sashing allowing for seam allowance.

12.5” should work

Two and a half inches (sashing width) plus ten and a half inches (block width) makes thirteen inches. Minus a half inch for the seam allowance makes it twelve and a half inches.

I'm going to go with 14.5. The block finishes at 10 and if you add 2.5 to each side (finish at 2) your measurement is now 14.5. It is 10 + 2 + 2 plus .5 for the seams that are not yet sewn (.25 inch on each side).

10.5 and 12.5 (assuming the 10.5" block is not a finished size )

take 1/4" off both the block and the side sash and it should come out at 12.5"....10.5 + 2.5 =13.0 - .5 = 12.5

I go with the 10.5 and 12.5 option with the L shaped sashing... or you could cut both at 12.5 and miter.

12.5" is correct. But you could just sew on the side sashing and then measure.<:)

I'm with Dunster. I would sew it on and cut it off and then measure the side. I tease my friends I don't like the math!!