What length? You count from the first day of one period to the first day of the next. Most women average 28 days, but some people go longer or shorter. You usually ovulate somewhere at the halfway point. So, if you have a 28 day cycle you start your period, then roughly 14 days later you ovulate, 14 more days you either start your period or you test to see if your prego. I hope that helps?
at 12:47 PM on Nov. 25, 2008