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Ovulation Calculator

Calculate your ovulation date and fertile window to help plan for pregnancy or understand your cycle.

Ovulation Calendar

Calculate your fertile window and ovulation date

How to Use This Calculator

  1. 1

    Enter last period date

    Input the first day of your last menstrual period.

  2. 2

    Enter cycle length

    Input your average menstrual cycle length (typically 21-40 days).

  3. 3

    Enter period length

    Input how many days your period typically lasts.

  4. 4

    View your fertile window

    See your ovulation date, fertile window, and cycle calendar.

Frequently Asked Questions

When do I ovulate?

Ovulation typically occurs 14 days before your next period. For a 28-day cycle, this is around day 14. Our calculator adjusts for your specific cycle length.

What is the fertile window?

The fertile window is typically 5 days before ovulation and 1 day after. Sperm can survive up to 5 days, while an egg is viable for 12-24 hours after release.

How accurate is this calculator?

This calculator provides estimates based on average cycle patterns. For more accuracy, consider tracking basal body temperature, cervical mucus, or using ovulation predictor kits.