Ovulation Calculator
Predict your most fertile days and ovulation window.
Ovulation Date
to-
Plan for Pregnancy with precision
Ovulation typically occurs 14 days before your next period starts. The most fertile days are the 5 days leading up to and including the day of ovulation.
Recommended Tools
Hand-picked utilities you might find useful
Estimating Your Fertile Window and Ovulation Day
Overview
Ovulation is when an ovary releases an egg, and the days around it are the most fertile of the cycle. This calculator estimates your likely ovulation day and fertile window from your last period and cycle length, in your browser. It is a guide, not a contraception or fertility guarantee.
How to Use (Step by Step)
- 1
Enter your last period date
The first day of your most recent period.
- 2
Enter your cycle length
The average number of days from one period to the next.
- 3
Read your fertile window
The tool highlights the estimated ovulation day and surrounding fertile days.
How It Works
Ovulation typically occurs about 14 days before the next period starts, so the tool counts backward from your estimated next period based on cycle length. The fertile window spans roughly the five days before ovulation plus the ovulation day itself, because sperm can survive several days. Cycle variability means these are estimates; ovulation tests or temperature tracking add precision.
When to Use This
Identifying the days most likely for conception. Understanding your cycle for family planning. Tracking your fertile window alongside other signs.
Frequently Asked Questions
Calendar estimates are not reliable contraception because ovulation timing varies. Use a proven contraceptive method if preventing pregnancy is the goal.
Important Notes
Fertility-window predictions are estimates and are not a reliable form of contraception or medical advice. Cycles vary — consult a qualified healthcare provider for family-planning or fertility guidance.