Usually - with most "modern" quilt patterns -
"finished size" is 1/2 inch smaller in both directions than "unfinished size"
Example:
Finished size block: 12 x 12 inches
Unfinished size block: 12-1/2 x 12-1/2 inches
The 1/2 inch disappears into the 1/4 inch seam allowance on each side of the block.
Or - you can lay out your pieces - subtract the seam allowances - and check it out that way