I am working on a quilt and have decided to use a sashing and an inner boarder. I'm stumped as to the size to cut this sashing and boarder. Is there a ratio to follow? I used a 2-1/2" sashing and boarder for a 12-1/2" block in another quilt I made. Now I'm using a 10-1/2" block and am wondering what size to make this sashing and boarder. Thanks so much!

I will watch this thread also, good ? thanks for asking it, others on here will be able to help with your ?

also can you post a photo of your quilt top so we can see it

On another thread someone mentioned that there is a ratio to follow, but for me I just eyeball it and do what I think looks best .

Yep - eyeball it to what looks good to me - and also how much fabric I have left over to use for borders - sometimes they have to be a bit narrower than I originally planned, bkz I don't have quite enough!

I agree with the eyeballing, but I normally go 2-1/2 for sashing and 3 for borders, depending on the pattern.

Part of it is determined by how big you want the finished product to be.
Depending on the pattern within the block, or a color that you want to accent throughout the rest of the quilt, you could use the measurement of a piece to determine sashing ...
If you consider that a sashing is actually an embellishment, whatever it is you are trying to accomplish by using sashing, that would be what dictates the size.
Try it with 2.5" sashing and see what you think ... <wave>