Ovulation Calculator

Estimate ovulation dates from your menstrual cycle.

Your Cycle Details

Enter period start date and cycle length

Last Period Start Date

Average Cycle Length

Next Ovulation Date

3-Cycle Overview

Enter your last period date to predict ovulation.

Step-by-step Solution

About Fertile Window

The fertile window is the 6 days around ovulation: 5 days before + the day of ovulation.

Ovulation typically occurs 14 days before the next period, regardless of cycle length.

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About This Calculator

Estimate ovulation dates from your menstrual cycle.

Everything is worked out in your browser as you type, so your figures never leave your device.

Pro Tips

Results update as you type — change any field to see the effect immediately.

Check that every value uses the same unit before comparing results.

Use the copy button to paste the ovulation figures into a note or spreadsheet.

Nothing is sent to a server, so you can use this with private figures.