I would not be exaggerating to say I have hemmed over 1000 pairs of pants, in my time, — everything from jeans to astoundingly expensive custom made mens wool pants. Some, like jeans and the expensive dress pants, should be taken to a professional – for lots of reasons. But, for the young wife, mom or GUY, you should know how to hem everyday pants, and by extension, skirts and shorts. So here is the quick version.
Put the pants on inside out. Turn the bottom of the pants up to the correct length, just form a cuff around the bottom. Pin this in place at the center back. Pin one leg only, and at this point only. The assumption is that both of your legs are the same length, or reasonably close to the same length, and that the pant legs are the same length to begin with.
Take the pants off; keep them inside out.
Measure the amount you turned up. Remove the pin and turn the pants up, by this amount, all around the pant leg. Press this ‘new hem’ fold.
Open the fold. Remove the previous hem stitching. The easiest way to do this is to use small sharp-tipped scissors and snip the threads on the surface of the hem, on the inside of the pant. Snip every third or fourth stitch. After snipping all the threads on the inside, the outside thread will easily pull away from the pant leg in one long piece.
Open the hem out and iron, being careful not to iron over the new hem fold.
Mark the cut line, from the new hem fold down toward the bottom of the pant leg,1 1/2 inches. Use a fabric marking pencil – or if you are confident, use a pencil and a light hand. Cut the pants off along this line.
Turn the cut raw edge up to meet the new hem fold line and press all around. Be careful not to press the new fold line. Turn the hem up again 3/4 inch. You have created a double hem, 3/4-inch wide. Sew around the pants, close to the folded edge. Done.