Menstrual Period Calculator

Predict your next menstrual period, ovulation day, and fertile window by entering your details below.

Typically between 21 and 35 days.
Results:

Next Period Start Date: -

Estimated Ovulation Day: -

Fertile Window: -

Menstrual Period Calculator Overview

Inputs:
  • Start Date of Last Period
  • Average Cycle Length (in days)
Outputs:
  • Next Period Start Date
  • Estimated Ovulation Day
  • Fertile Window
Calculation Logic:
  • Next Period Start Date: Last Period Start Date + Cycle Length
  • Ovulation Day: Next Period Start Date - 14 days
  • Fertile Window: Ovulation Day - 5 days to Ovulation Day + 1 day

Note: These are estimates based on average cycle patterns. Individual cycles may vary. Consult a healthcare provider for precise tracking.

Frequently Asked Questions

The Menstrual Period Calculator predicts your cycle by using the start dates of your previous periods and the average length of your cycle (typically 28 days). It estimates future period dates and ovulation windows based on this data, helping you plan for upcoming cycles.

The ovulation window is the time during your cycle when you’re most fertile, typically 5 days before ovulation through 1-2 days after. It’s important for those trying to conceive or avoid pregnancy, as it indicates the best time for conception or when to take extra precautions.

The calculator’s accuracy depends on the regularity of your cycle and the accuracy of the data you provide. If your cycles vary significantly (e.g., more than 8 days difference between cycles), the predictions may be less accurate. It’s best used as a guide, not a definitive prediction.

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