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Cycle Length Calculator
Track your menstrual cycles to understand patterns, predict future periods, and monitor your reproductive health.
Add Period Data
First day of bleeding (this is what cycle length is measured from)
Last day of bleeding
💡 Tracking Tips
- • Track at least 3 cycles for accurate patterns
- • Record the first and last day of bleeding
- • Include light spotting as part of your period
- • Note any unusual symptoms or changes
How to Use This Calculator
1
Track Your Periods
Enter the start and end dates of your recent periods. Your cycle length is measured from the first day of one period to the first day of the next, so log at least 3 periods.
2
Get Analysis
After adding 3 or more periods, you'll receive detailed analysis including average cycle length, regularity, and health insights.
3
Plan Ahead
Use predictions for your next periods to plan activities, travel, or fertility awareness.
Normal Cycle Information
- • Normal cycle length: 21-35 days
- • Average cycle length: 28 days
- • Menstrual flow: 3-7 days
- • Slight variations month to month are normal
Understanding Menstrual Cycles
Learn about normal cycle patterns and when to seek medical advice.
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Normal Variations
- • Cycle length: 21-35 days
- • Period duration: 3-7 days
- • Monthly variation: ±2-3 days normal
- • First year after menarche: irregular
- • Approaching menopause: may vary
- • Stress can affect timing
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When to See a Doctor
- • Cycles shorter than 21 days
- • Cycles longer than 35 days
- • Missing periods (not pregnant)
- • Extremely heavy bleeding
- • Severe pain or cramping
- • Sudden changes in pattern
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Tracking Benefits
- • Family planning assistance
- • Health pattern monitoring
- • Early problem detection
- • Travel and event planning
- • Medical appointment preparation
- • Symptom correlation tracking