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You’ll be measuring from the crown of your head, so let down your hair from any high ponytails or braids that might boost your height. Also take off your shoes, which can add several inches to your height depending on the style. If you're wearing thick socks, remove those as well. Your feet should be together and flat on the floor. Your heels should also be flush against the wall. It’s easiest to have another person measure your height, but you can also do this alone.  Do not stand on a carpet or a rug, which will sink a bit when you stand on it and may affect your measurement. Also avoid walls with molding or radiators along the bottom, which will make it impossible for you to stand fully flush against the wall. You can also use another common household item that is flat and firm—for example, a cutting board or a cardboard box. If you have a partner, have them hold the headpiece. If you are measuring alone, it may be easier to use an aerosol can such as a shaving cream can or air freshener. Press the bottom flat against the wall, which will ensure a right angle. Regardless of what item you are using to measure, it should be firmly in contact with the crown of your head. Make sure it stays at a right angle with the wall as you or your partner move it down to touch your head. If you have a partner, they should do this while you’re still standing against the wall. If you’re alone, hold the headpiece in place while you turn and mark the location. Use a pencil so you can erase the mark from the wall when you’re done.

Summary:
Remove your shoes and any hair accessories that might get in the way. Stand with your back against the wall on non-carpeted flooring. Position a book at a right angle with the wall above your head. Slide the headpiece down the wall until it touches your head. Mark where the bottom of the headpiece meets the wall with a pencil.