Health & Fitness Calculators
Period Calculator
Predict your next periods and ovulation.
FreeNo sign-upWorks in your browser
Next period
Sun, August 9, 2026
Following period
Sun, September 6, 2026
Estimated ovulation
Sun, July 26, 2026
About the Period Calculator
Enter the first day of your last period and your average cycle length and the calculator predicts your next two periods and your estimated ovulation date. It's a simple way to plan ahead and understand your cycle — for medical concerns, always consult a healthcare provider.
How to use the Period Calculator
- 1Enter your first day of last period and average cycle length.
- 2Read the result instantly — it recalculates as you type.
- 3Adjust the numbers to model different scenarios.
Frequently asked questions
How is my next period predicted?
By adding your average cycle length to your last period's start date. Track a few cycles for a more accurate average.
Why is my cycle irregular?
Stress, weight changes, and health conditions can shift cycle length. If it's very irregular, consider speaking with a doctor.