Are you saying you’re sewing 4 strips (1.5 inches each) together? When you use 1/4 inch seam, it takes 1/4 inch off each piece, or 1/2 inch per seam.
So you should end up with 4.5 inches wide. (1.5 x 4 = 6. 6-.5-.5-.5 =4.5. That’s your unfinished block width. When you see it into the quilt, your seams will subtract rei more 1/4 inches (so 1/2in). 4.5-.5 = 4. So your finished block (that is, once it’s in your quilt, will have 4 inch blocks. Unfinished will always be 1/2” more than finished.
Does that make sense?