I have a six inch block that I want to set on point and can't remember the measurement you add to make the half-square triangle. Do you add 1 7/8"???? So to make hst block would need to be cut 7 7/8'? I know I have this in a quilting book somewhere but it's easier to ask my friends.

For a 6 inch block: 6 x 1.414 = 8.484 or 8 1/2 inches. Add the 1 1/4 for seam allowances = 9 3/4 inches.

Thanks a million. I had it all wrong. Knew some smart person would know this. I'll print and save in a safer place.

PS. Why 1 1/4" for seam allowances instead of 1/2"?

I don't know. I just googled it and this is the formula.

Thanks for the info.