No matter the length of her period, every woman ovulates about 14 days before her next period. So, if you have a 28-day cycle, you’ll ovulate on day 14, and if you have a 32-day cycle, you’ll ovulate on day 18. But, when you have an irregular cycle, identifying an ovulation date isn’t so easy, because without knowing when you’re going to get your period, you don’t know when to count back 14 days from.