Ovulation Calculator

Estimate ovulation and fertile window from cycle length and last period date.

Scratchpad (not saved)

What This Calculator Does

Estimate ovulation and fertile window from cycle length and last period date.

It combines LMP Year, LMP Month, LMP Day, Cycle Length to estimate Estimated Ovulation Date, Fertile Window Start, Fertile Window End.

Formula & Method

Core equations: Ovulation estimate: D_{ovu}=D_{LMP}+L-14; fertile window commonly [D_{ovu}-5, D_{ovu}+1].

Notation used in the formulas: R = Estimated Ovulation Date; x_{1} = LMP Year; x_{2} = LMP Month; x_{3} = LMP Day; x_{4} = Cycle Length.

Method summary: inputs are normalized to consistent units, core equations are evaluated, then secondary values are derived and rounded for display.

Use this calculator for quick scenario analysis. Start with baseline values, change one driver at a time, and compare how sensitive the results are to each input shown above.

Inputs Used

  • LMP Year: Used directly in the calculation.
  • LMP Month: Used directly in the calculation.
  • LMP Day: Used directly in the calculation.
  • Cycle Length: Used directly in the calculation.

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