Ovulation Calculator
Estimate ovulation and fertile daysRuns locally · nothing uploaded
Estimates based on general formulas, for information only. Not a substitute for professional medical advice, diagnosis or treatment.
Uses the calendar method (ovulation about 14 days before the next period). It's less accurate for irregular cycles and must not be used as birth control. Use ovulation tests or ask a clinician for certainty.
Also works as:fertile window calculatorovulation date calculatorwhen do I ovulate
How to use
- 1Choose the first day of your last period.
- 2Enter your average cycle and period length.
- 3See your ovulation day, fertile window and calendar.
FAQ
How is ovulation estimated?
In regular cycles ovulation happens about 14 days before the next period. The fertile window is roughly the 5 days before ovulation plus the day after.
Can I use this for contraception?
No. Ovulation can shift with stress or illness, and calendar methods have high failure rates.