Ovulation typically occurs 14 days before the next period. For a 28-day cycle, that is day 14. For a 30-day cycle, it would be around day 16.

What is the fertile window?

The fertile window is the 5–6 days when pregnancy is possible: the 5 days before ovulation and the day of ovulation itself. Sperm can survive up to 5 days in the reproductive tract.

Ovulation Calculator – Fertile Window & Ovulation Date

Ovulation Calculator

Find your fertile window and ovulation date based on your last period and cycle length.

First day of last period (LMP)

Cycle length (days)

Cycles to show

Ovulation date

Thu, May 28

Fertile window

Sat, May 23 – Fri, May 29

Days to ovulation

14

Cycle	Period starts	Fertile window	Ovulation
1	May 14, 2026	May 23, 2026 – May 29, 2026	May 28, 2026
2	Jun 11, 2026	Jun 20, 2026 – Jun 26, 2026	Jun 25, 2026
3	Jul 9, 2026	Jul 18, 2026 – Jul 24, 2026	Jul 23, 2026

Ovulation typically occurs 14 days before the next period. The fertile window is the 5 days before ovulation plus ovulation day. Sperm can survive up to 5 days.

Ovulation Calculator

The Ovulation Calculator predicts your ovulation date and fertile window based on your last menstrual period and cycle length.

How ovulation is calculated

Ovulation = LMP + cycle length − 14 days. The luteal phase (post-ovulation) is nearly always 14 days regardless of cycle length; it is the follicular phase that varies.

Fertile window

The 6-day window ending on ovulation day has the highest pregnancy probability. Days −5 to 0 relative to ovulation are considered fertile.