Using the calculator
Enter First day of last period, Average cycle length, Luteal phase length. Estimate ovulation date and fertile window from the first day of the last period and typical cycle length.
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Ovulation Calculator
Estimate ovulation date and fertile window from the first day of the last period and typical cycle length.
Enter your measurements and health details
Use current, consistently measured values for the ovulation calculation. Results update automatically and are intended for education and planning, not diagnosis.
days
days
Estimated ovulation date—
Estimated fertile window starts—
Estimated fertile window ends—
Estimated next period—
Important: Health results are educational screening and planning estimates. They are not a diagnosis and are not a substitute for medical care.
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How to use this calculator
Reading the result
The result shows ovulation date and fertile window from the first day of the last period and typical cycle length.
Results are estimates based on the values entered. Review the Methodology and Calculator Disclaimer for important limitations.