How many days late on your menstrual cycle is normal?

Depends: Some women have a 28 day cycle and some have a 35 day cycle, so being 5 days late for each of those women as an absolute number is going to mean something different. Basic rule of thumb, though, if you're more than 5-7 days late, you're likely late. Could be stress, weight gain/loss, hormones, thyroid or pregnancy. See your doctor if you're worried.