My first teacher drilled into me the 'scant 1/4 inch'. I can get it perfect if I use the Featherweight, that machine does it without me. The regular 1/4 inch is just that, it can be measured 1/4 inch if you take the ruler to it. But the scant 1/4 is less, noticable to me and to you. It is not an 1/8 for sure, but definitely not a 1/4 inch. This is my best definition: do not sew 1/4 inch but more than 1/8th.