◑ HEALTH Updated July 25, 2026

Ovulation Calculator

Fertile window and ovulation day estimate.

First day of last period
Cycle length (days)
Result
Ad space · belowTool · horizontal

How it works

Ovulation is estimated 14 days before the next expected period, and the fertile window covers the five days before ovulation plus the day itself.

Related tools

◕BMR Calculator◈Calorie Calculator▣Body Fat Calculator

Frequently asked questions

How long does sperm survive?

Up to five days in fertile cervical mucus, which is why the fertile window starts before ovulation.

Is this reliable for contraception?

No. Calendar methods are not a reliable form of birth control.

Comments

Comments aren't enabled yet. When you're ready, this is where a service like Giscus, Disqus, or a custom form would go — the slot is already reserved on every tool page.