How to Hem Pants. Do you have a pair of pants that you can't fit in anymore, or even a new pair that just need a few modifications before they fit perfectly. Whether you're tailoring new clothes or adapting hand-me-downs, you'll want to get the hem right. Here is how you do it.
Select thread that matches the color and thickness of the thread used in the original hem.
Use small scissors or a seam ripper to undo the existing hem carefully.
Try on the pants and fold each pant leg inward to the length that looks correct for the new hem. Pin it in place.
Take off the pants, turn them inside out, and use a tape measure or ruler to determine the length of the fabric folded inward to form the new hem length. Use this measurement as your gauge for folding the pant legs all the way around.
Measure and pin the new hem length into place on both legs according to the measurement that you just made.
Iron the edge of the new hem on both legs to create a good crease. (If you want to hide the unfinished edge of the fabric to prevent fraying, fold it approximately 1/4 inch toward the inside of the pant leg and iron it in place.)
Try on pants with the appropriate shoes and hem accordingly. With lined pants, the lining is typically hemmed slightly shorter than the pants.