Ovulation Calculator

Ovulation Calculator – Quick Cheat Sheet

Inputs: LMP (first day of last period), Cycle length (avg), Luteal (avg).
Next period ≈ LMP + cycle length.
Ovulation ≈ Next period − luteal length (commonly ~14 days).
Fertile window = Ovulation − 5 days → Ovulation day.
Peak days: the day before and the day of ovulation.
Ranges: cycle typically 21–45 days; luteal often 10–16 days.
Note: Estimates only; individual cycles vary. Consider confirming with ovulation tests or professional guidance.

Edge cases & notes

Irregular cycles: try using the most recent average; wide variability reduces accuracy.
Changing luteal length shifts the ovulation date relative to the next period.
All calculations use strict UTC calendar math with YYYY-MM-DD parsing.