Ovulation Calculator
Enter your last period date and cycle length to find your estimated ovulation day and 6-day fertile window.
Use the Ovulation Calculator
Your Cycle Details
The date your most recent period started.
Cycle Timeline
Calendar View
Medical disclaimer: This calculator provides estimates based on average cycle patterns and is intended for informational purposes only. Actual ovulation timing varies. Consult a healthcare professional for personalized fertility advice or medical decisions.
Enter your cycle details and click Calculate to see your fertile window.
Summary
This ovulation calculator estimates your most fertile days by applying the standard rule: ovulation typically occurs 14 days before the start of your next period. Enter your last menstrual period (LMP) start date and your average cycle length to get an instant estimate of your ovulation date, the 6-day fertile window, and your next expected period. Results are displayed on a visual calendar so you can plan ahead at a glance.
How it works
- Enter the first day of your last menstrual period (LMP).
- Select your average cycle length (typically 21–35 days).
- Click "Calculate" to generate your fertility forecast.
- The tool subtracts 14 days from your next expected period to estimate ovulation.
- Your fertile window spans 5 days before ovulation through ovulation day itself.
- A mini calendar highlights the fertile window and ovulation day in your current cycle.
Use cases
- Planning conception by identifying peak fertility days.
- Tracking your menstrual cycle and predicting the next period.
- Understanding natural family planning (NFP) methods.
- Sharing cycle data with a healthcare provider.
- Identifying irregular cycle patterns over multiple months.
- Preparing for fertility appointments with documented cycle data.