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Calcimator

Menstrual Cycle Tracker Calculator

Track your menstrual cycle, predict ovulation day, fertile window, and next period based on cycle length and variation.

Inputs

days
days
days

Results

Estimated Ovulation (cycle day)

14

Fertile Window Start (cycle day)9
Fertile Window End (cycle day)15
Fertile Window Length7 days
Next Period (est. day of month)29
Follicular Phase Length14 days
Luteal Phase Length14 days
Estimated Lower Fertility Window3 days
Cycle Regularity Score90/100
How to Use This Calculator
  1. Enter Average Cycle Length, Period Duration, and Last Period Start (day of month).
  2. Set Cycle Variation.
  3. Review the Estimated Ovulation (cycle day) result.
  4. Use Fertile Window Start (cycle day) and Fertile Window End (cycle day) to inform your decision.
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