Period Calculator
Predict your next period, ovulation day, and fertile window with precision. Log cycles securely on your device.
Your Cycle Forecast
Next Period Starts
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Estimated Ovulation
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Fertile Window
Fertile Window
Predictions assume a regular menstrual cycle. If your cycles are highly irregular, use these dates as a rough guide. Logging your cycles over 3–6 months will significantly improve accuracy.
Frequently Asked Questions
How accurate is this period calculator?
It's highly accurate for individuals with a regular menstrual cycle (typically 21–35 days). If your cycles are highly irregular, the predictions act as estimates. We recommend tracking consistently over several months for optimal accuracy.
What is a normal menstrual cycle length?
The typical cycle length ranges from 21 to 35 days, with 28 days being the most common average. Variations of a few days from month to month are completely normal.
When exactly do I ovulate?
Ovulation generally happens around 14 days before your next expected period. In a standard 28-day cycle, ovulation typically occurs on day 14 (counting from the first day of bleeding).
Is it possible to get pregnant outside my fertile window?
Pregnancy almost exclusively occurs during the fertile window, which includes the 5 days leading up to ovulation and the day of ovulation itself. This is because sperm can survive in the female reproductive tract for up to 5 days.
What should I do if my cycles are highly irregular?
This calculator provides a baseline estimate. For very irregular cycles, you might want to combine this with tracking basal body temperature, monitoring cervical mucus, or using over-the-counter ovulation predictor kits.
Medical Disclaimer:This calculator provides estimates based on generalized data and is for informational purposes only. It is not intended for use as a primary contraceptive method or medical diagnosis. Please consult a healthcare professional for personalized medical advice.