Ovulation Calculator

Worth Knowing

This estimates ovulation as roughly 14 days before your next expected period, since the luteal phase (ovulation to period) is fairly consistent while the follicular phase varies. The fertile window spans the five days before ovulation plus the day itself, because sperm can survive several days in the reproductive tract while the egg lives only about 24 hours. Calendar estimates are approximate — ovulation timing shifts with stress, illness, and cycle irregularity — so pair them with ovulation tests or temperature tracking if timing matters.

How to Use

1. Enter Last menstrual period into the first field of the Ovulation Calculator.
2. Fill in the rest: Cycle length.
3. Your result appears instantly as you type — there's no submit button or page reload.

Frequently Asked Questions