Ovulation Calculator

Enter the first day of your last period and cycle length to estimate ovulation day and fertile window.

Notes & Explanation

Ovulation typically occurs about 14 days before your next period. The fertile window includes the 5 days before ovulation and the ovulation day itself. This tool estimates based on the dates you enter — results are approximate.


Example values used:
  • First day: Aug 12, 2025
  • Cycle length: 28 days