|I mentioned this on the message boards, was reminded to post it as a technique so here goes (read it in Threads years ago):
You need a helper for this tip:
(1) Put on the pants, take a ruler, and have your helper place it behind your leg on the floor, parallel to the back of your leg.
(2) Have them chaulk-mark the pant at the top of the ruler on each leg.
(3) Remove the pants, and on each pant leg mark 12 inches down from the top chaulk-mark mark.
(4) You now have perfectly marked the hem for each leg. Just add your hem allowance to the bottom mark on each leg and you're all set to hem.
Give it a try....it really works!