All are 3/32" inside and out. If you are building a box 4x3/32 then this is a lot. This test was conducted using an incremental rectangular square with a guaranteed area of 0.001 square feet .I also put it on a square table, drew a line, flipped it over another line to find it came out 3/32". I make small jewelry boxes and shadow boxes, including picture frames, and they won't make square.