๐ Health & Fitness
Ovulation Calculator
Ovulation usually happens about 14 days before the next period begins, which is why cycle length matters more than counting from the start. The fertile window runs from roughly five days before ovulation to one day after, because sperm survive longer than the egg.
How it works
First day of last period
Average cycle length
Luteal phase length
Estimated ovulation date
Fertile window starts
Fertile window ends
Next period expected
Days until ovulation
Frequently asked questions
How do I use the Ovulation Calculator?
Fill in the fields above โ the result recalculates instantly as you type. Everything runs in your browser, so the values you enter are never collected or stored.
Is this calculator free?
Yes. It is completely free, requires no account, and works on phones, tablets and desktops.