Ovulation Calculator

When does ovulation happen?

Ovulation is the release of an egg from the ovary, once per cycle. In a regular cycle it usually happens about 14 days before the next period (the length of the luteal phase) — not always mid-cycle as many believe. In a 28-day cycle that's around day 14; in a 32-day cycle, around day 18.

What is the fertile window?

An egg survives only 12–24 hours after release, but sperm can live up to 5 days in the female body. The fertile window therefore spans about six days: the five days before ovulation plus ovulation day itself. Chances of conception are highest in the two days before ovulation and on the day itself.

How to use it

1. Enter the first day of your last period (first day of bleeding).
2. Enter your average cycle length — days from the start of one period to the start of the next.
3. Leave the luteal phase at 14 days unless your doctor told you otherwise.
4. See your next three cycles with fertile days, ovulation day and next period.

Signs of ovulation

• Clear, stretchy cervical mucus resembling raw egg white.
• A slight rise (0.2–0.5 °C) in basal body temperature after ovulation.
• Mild one-sided lower abdominal pain for some women.
• A positive home ovulation (LH) test 1–2 days before ovulation.

Tips to improve your chances

• Focus on the fertile window, especially the two days before ovulation.
• Use ovulation test strips for more precision if your cycles vary.
• Maintain a healthy weight, sleep well and take folic acid before conceiving.
• Once pregnant, find your due date with the Pregnancy Calculator.

⚕️ Results are estimates that assume a regular cycle and must not be used as contraception. If you haven't conceived after a year of trying (or six months over age 35), see a doctor.

Frequently Asked Questions

Last updated: 2026-10-20