How do you sew a hem by hand?

Have the garment worn (inside out) by a person, or use a dressmaker's manikin to establish the correct length for the hem. Mark with chalk or pin with straight pins.

Remove the garment and press the hem. Straighten the hem flat and turn down, a small amount of the "hem" material, and once again press the fabric - this will keep the fabric from fraying. If there is not enough extra fabric to do this step use a commercially available fray-stop liquid.

Fold the hem into place with the extra inside between the hem material and the garment.

Taking needle and thread, (use a colour matching the fabric for the thread), place a knot in the end of the thread. Catch a small amount of the upper edge of the hem with the needle and take a very small vertical stitch into the garment, pull thread through to the knot, move about an inch along the hem and take another stitch and pull the thread through until it is taught, but not so tight as to bunch the fabric. Be sure the hem is laying flat to the garment and continue stitching until you reach the end of your thread or the starting place of the hand work. Secure the thread with a knot and if you have not completed the hem, re-thread the needle and continue.

When you have completed the hem, cut the thread, make sure the work is tidy (no hanging threads etc), turn the garment right side out and you are finished.