📅

Period Calculator

Predict your next 6 periods, ovulation days and fertile windows based on your cycle.

First Day of Last Period

Average Cycle Length (days)

Average Period Duration (days)

Fertile window shown as 3 days before ovulation through 1 day after. For informational purposes only.

Your files are processed securely and automatically deleted after 1 hour. We never store or share your data.

About Period Calculator

Our free Period Calculator helps you run quick, accurate calculations for everyday financial and mathematical needs with just a few inputs. Predict your next 6 periods, ovulation days and fertile windows based on your cycle. Enter your values, and the calculator instantly shows detailed results with breakdowns you can understand. No signup, no ads interrupting your workflow — just accurate, reliable calculations you can trust. Works on any device, saves nothing to our servers.

📖