Period Calculator
Predict your upcoming menstrual cycles, estimate your fertile windows, and plan ahead with our easy-to-use tracker.
Cycle Details
Usually between 21 and 35 days (Average is 28).
Usually between 3 and 7 days.
Enter your cycle details to predict your next periods and fertile windows.
Disclaimer
This calculator provides estimates based on averages. Menstrual cycles can vary significantly from person to person and month to month due to stress, diet, exercise, or medical conditions. Do not use this tool as a form of birth control.
Women's Health Calculators
Related Calculators & Companion Tools
Complementary tools designed to pair with the Period & Menstrual Cycle Calculator. Compare formulas and verify your projections.
Pregnancy Calculator
Calculate your estimated due date based on your last menstrual period and gestational age.
Ovulation Calculator
Estimate your most fertile days, next ovulation date, and fertile window.
BMI Calculator (Men & Women)
Calculate your Body Mass Index (BMI) in lbs/inches or metric with adult Male & Female CDC charts, healthy weight ranges, and athletic adjustments.
Body Fat Calculator
Estimate your body fat percentage, lean body mass, and fat mass using U.S. Navy tape measurements.
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Interactive Google Health Web Stories & Visual Guides
Explore fast, mobile-first visual stories on BMI, Calorie Deficit, TDEE, Macros, Sleep Cycles, and Healthy Habits.
Evidence-Based Clinical Formulations
All biometrics, body composition, and caloric computations adhere to the Mifflin-St Jeor, Harris-Benedict, and U.S. Navy standards referenced by the Centers for Disease Control and Prevention.
Cardiovascular & Nutrition Tips
Target heart rates, daily sodium ceilings, and macronutrient distributions align with the American Heart Association (AHA) and USDA Dietary Guidelines for Americans.
Practical Health Takeaways
Pair your calculation with structured sleep (7-9 hrs), balanced hydration (half body weight in oz), and a 500 kcal sustainable deficit for healthy body composition management.