probably best to measure it in time. that is, a clean shave is length 0, time since last shave estimates length. If you use an electric shaver, the settings on the shaver associate to a known length. If you trim with scissors... that's a bit trickier.
probably best to measure it in time. that is, a clean shave is length 0, time since last shave estimates length. If you use an electric shaver, the settings on the shaver associate to a known length. If you trim with scissors... that's a bit trickier.