I need to make a couple blocks to fill in a quilt . I want to make it 12 1/2 inch unfinished dissappearing 9 patch.. What size do I cut the 9 separate blocks for it? I was thinking they need to be 4 1/2 inches each.
Thank you , Elaine

Yes, the blocks need to be 4 1/2

Great , Thanks Terri

Wouldn't you need an extra 1/2" vertically and horizontally to account for the extra seams when you cut them apart? I've never made one, so I don't know, just asking.

wouldn't one cut the corner blocks 4-1/2 x 4-1/2
the center one 5 x 5
the center side ones 4-1/2 x 5

??

I believe you're correct. Once you sew your 9 blocks together to make the 9 patch, then you cut them once vertically and horizontally. Once you've rearranged these new 4 pieces, then, you sew the top two halves together, the bottom two halves, and finally the top and bottom together. (if I remember correctly)