Ovulation Calculator
Enter the first day of your last period and your typical cycle length.
Most fertile day
Aug 19, 2026
Estimated ovulation day
- Fertile window starts
- Aug 14, 2026
- Fertile window ends
- Aug 20, 2026
- Next period
- Sep 2, 2026
How it works
Ovulation is typically 14 days before the next period. The fertile window spans 5 days before to 1 day after, since sperm survive up to 5 days.
Formula
Ovulation = LMP + (cycle length − 14)
Worked example
Cycle began Jun 1, length 28: ovulation ≈ Jun 15.
FAQ
- Accuracy?
- Estimate — best when cycles are regular.
- For contraception?
- No — see a doctor for reliable methods.
- When to try?
- Throughout the full fertile window.