Ovulation Calculator

Calculate your ovulation date and fertile window based on your menstrual cycle. Plan for conception with a visual fertility calendar showing upcoming cycles.

First Day of Last Period *

Average Cycle Length

21-40 days (default: 28)

Average Period Length

2-10 days (default: 5)

Luteal Phase Length

10-16 days (default: 14)

How to Use Ovulation Calculator

1Enter the first day of your last period.
2Set your average cycle length.
3View your estimated ovulation date.
4See your full fertility window.

Frequently Asked Questions

When do I ovulate?▾

Ovulation typically occurs 14 days before your next period. For a 28-day cycle, that's around day 14. For a 30-day cycle, around day 16.

What is the fertile window?▾

The fertile window is about 6 days: the 5 days before ovulation plus the day of ovulation. Sperm can survive up to 5 days, and the egg lives for 12-24 hours after release.

How accurate are ovulation calculators?▾

Ovulation calculators provide estimates based on average cycles. For more accuracy, combine with ovulation predictor kits (OPKs), basal body temperature tracking, or cervical mucus monitoring.

About Ovulation Calculator

Calculate your ovulation date and fertile window based on your menstrual cycle. Plan for conception with a visual fertility calendar showing upcoming cycles.

NexTool's Ovulation Calculator is completely free to use with no sign-up required. Your data is processed directly in your browser and never sent to our servers, ensuring complete privacy and instant results.