Ovulation Calculator
HealthPredicts the fertile window and ovulation day based on menstrual cycle length.
How to use this calculator
Start with your values, or try a preset.
Enter Average Cycle Length (days) and First Day of Last Period in the units shown.
Read Estimated Ovulation Day, Fertile Window Start, and Fertile Window End in the results panel. Results update as you change the inputs.
Choose a preset to load an example, then adjust the values for your situation.
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