Ovulation Calculator

About the Ovulation Calculator

Knowing your ovulation date helps identify your most fertile window, which is useful whether you're trying to conceive or simply tracking your cycle.

Formula Used

Ovulation Date = LMP + (Cycle Length - 14) days

How It Works

This calculator estimates ovulation as 14 days before your next expected period, based on the start of your last period and your average cycle length.

Step by Step

  1. Enter the first day of your last period.
  2. Select your average cycle length in days.
  3. Ovulation is estimated 14 days before your next expected period.

Worked Example

Example: LMP on 1 January, 28-day cycle:

Ovulation = 1 January + (28-14) = 1 January + 14 = 15 January

Frequently Asked Questions

How long is the fertile window?

The fertile window typically spans about 5 days before ovulation through the day of ovulation itself, since sperm can survive for several days.

Does ovulation always happen on day 14?

Not necessarily - day 14 is typical for a 28-day cycle, but ovulation timing shifts with your actual cycle length.

Can stress affect ovulation timing?

Yes, stress, illness, and lifestyle changes can shift ovulation earlier or later than predicted.