Ovulation Cycle Calculator
Identify peak fertility windows based on LMP and cycle lengths. Fast, free, and fully client-side.
Calculator Inputs
Last Period Start Date
Average Cycle Length (days)
Estimated Ovulation Day—
Fertile Window (Range)—
How the Ovulation Cycle Calculator Works
Calculates the estimated ovulation window and fertile days based on menstrual cycle length, assisting individuals in tracking fertility and conception windows.
Formula
Ovulation Day = Cycle Length - 14 Days from Expected Next Period
The luteal phase between ovulation and the next cycle is typically consistent at approximately 14 days.
Calculation Example
In a standard 28-day cycle starting on Day 1, ovulation typically occurs around Day 15, with the fertile window spanning Days 10 to 15.
Frequently Asked Questions
How long does the fertile window last?
Sperm can survive in fertile cervical mucus for up to 5 days, while an egg survives 12 to 24 hours after release, creating a 6-day fertile window.