I've always heard that to test the accuracy of your seam allowance, you cut three 2 1/2 inch squares and sew them together and then measure the finished product. It should measure 6 1/2 inches and the center square should be 2 inches wide.
I have a feeling that the thickness of your fabric, thread or both are causing the blocks to come out smaller.
Last edited by cashs_mom; 07-27-2022 at 07:32 PM.