To mark a hem without a helper, I stretch a string tautly across a doorway at the desired hem height and tack or tape it to the jamb on both sides. I then dust bath powder onto the string. With the unhemmed garment on, I brush lightly against the powdered string, which transfers a light dusting onto the garment at the correct height. I can then remove the garment and finish the hem, and it will be perfectly parallel to the floor. This works great for skirts, dresses, and coats.
-Bonnie Wheaton, Wheaton, Ill.
That's brilliant!
Thank you for sharing