Ovulation Day for a 31 Day Cycle

For a 31 day cycle, ovulation typically occurs on cycle day 17. Your fertile window is between day 12 and day 18.

How to calculate ovulation for a 31 day cycle? Get your fertile window and exact ovulation day for a cycle length of 31 days.

Ovulation Day

Day 17

Fertile Window

Day 12â€“18

Peak Fertility

Day 16

Calculate your personal ovulation window

Quick Answer: Quick Answer: Ovulation typically occurs approx. 14 days before the next period starts — for a 28-day cycle, that's day 14.

First day of last period *

Cycle length (days)

Typical range: 21–45 days (avg. 28 days)

Period duration (days, optional)

For a more accurate calendar view

Irregular cycle

Shows a wider fertile window with lower confidence

When is ovulation for a 31 day cycle?+

For a 31 day cycle, ovulation typically occurs on day 17 of your cycle, which is 17 days after the start of your last period.

What is the fertile window for a 31 day cycle?+

The fertile window includes days 12 to 18 of your cycle. These are the 6 days during which conception is possible.

Is a 31 day cycle normal?+

Yes, a 31 day cycle is within the normal range. A normal cycle is generally considered to be between 21 and 35 days.