Ovulation Calculator
This free ovulation calculator estimates the day you ovulate and your fertile window, the days each cycle when conception is most likely.
Ovulation is also when estrogen and testosterone peak, so even if you are not trying to conceive, knowing this window tells you when your energy, confidence, and libido are naturally highest.
Sync your whole cycle, automatically
PhaseBloom builds your meals, workouts, and skincare around your exact cycle phase, day by day.
How it works
Ovulation usually happens about 14 days before your next period, not 14 days after your last one. That is why cycle length matters for the estimate.
The fertile window spans roughly the 5 days before ovulation plus ovulation day, because sperm can survive several days while the egg lives about 24 hours.
Frequently asked questions
When do I ovulate?
For most people ovulation happens around 14 days before the next period starts. On a 28-day cycle that is about day 14; on a 32-day cycle it is closer to day 18.
Can I use this to avoid pregnancy?
No. Calendar estimates are not reliable contraception because ovulation timing shifts. Use a medically approved method for birth control.