Rhonda K

Re-check your squaring up technique.

I see that the "diagonal line" of the ruler is not going through the first white square (upper right side) at the point.

Tilt the ruler so it on the diagonal throughout the block and then square up.

Another issue may be that you are putting the line "UP" to the fabric and cutting. You want the ruler line to cover the fabric and be "ON" the fabric. It's a few threads but will make a difference.

If you are starching and pressing after sewing the blocks, that can cause shrinkage too.

PS: If you are using two different rulers for cutting & squaring up they could be off on the measurements.