Calculate Length of Menstrual Cycle

Menstrual Cycle Length Calculator

All you need is the date when your last two periods started and you can figure out how long your menstrual cycle is. When you have that magic number, you can plug it into our ovulation calculator and find your most fertile days for getting pregnant.

Date Period started in First Month:
Date Period started in Next Month:
Your cycle length: days.


Now that you know how long your menstrual cycle is, you can use our free online ovulation calculator to find out which days you have the best chance of getting pregnant.