Ovulation Calculator

Estimate your ovulation day and most fertile window from your cycle.

First day of last period

Average cycle length (days)

Estimates only. Cycles vary — track a few months for accuracy or consult a professional.

Estimated ovulation day

Mon, September 21, 2026

Most fertile: 9/16/2026 – 9/22/2026

Fertile window starts

9/16/2026

Fertile window ends

9/22/2026

Ovulation

9/21/2026

Next period

10/5/2026