Ovulation Calculator

Find your ovulation day, fertile days and peak fertility. Free, private and instant.

How to use the Ovulation Calculator

  1. Pick first day of your last period.
  2. Enter average cycle length (days).
  3. Choose luteal phase (ovulation to next period): 10 days, 11 days, 12 days, 13 days and more.
  4. Press Calculate to get an instant result with a colour scale, chart and plain-English explanation.

About the Ovulation Calculator

The ovulation calculator estimates the day you are most likely to ovulate from your last period date and cycle length. Ovulation happens about 14 days before your next period, and your most fertile days are the 2 days before and the day of ovulation.

Also known as: ovulation date calculator, when do I ovulate, ovulation tracker, fertility calculator, most fertile days calculator.

Worked example

Dates in this example are worked out as if today were 5 Nov 2026.

Ovulation is expected: today (Ovulation 5 Nov 2026). Based on a 28-day cycle, you are likely to ovulate on Thu, 5 Nov 2026. Your most fertile days are 3 Nov - 5 Nov 2026.

Formula and cut-offs

Ovulation day = cycle length - luteal phase (usually 14 days), counted from day 1. Fertile window = ovulation day - 5 to ovulation day + 1. Chance of pregnancy per day (approx.): -5: 10%, -4: 16%, -3: 14%, -2: 27%, -1: 31%, ovulation day: 33%.

Frequently asked questions

When do I ovulate in a 28-day cycle?

Usually around day 14, counting the first day of your period as day 1. With a 32-day cycle it is around day 18.

What are the signs of ovulation?

Clear stretchy cervical mucus, a mild one-sided pain, a slight rise in basal temperature and a positive LH test.

How long does the egg live?

About 12 to 24 hours, but sperm can survive up to 5 days, so sex before ovulation can lead to pregnancy.

When will I ovulate if my last period started on 22 Oct 2026 and my cycle is 28 days?

Based on a 28-day cycle, you are likely to ovulate on Thu, 5 Nov 2026. Your most fertile days are 3 Nov - 5 Nov 2026. This example treats 5 Nov 2026 as today. Enter your own dates above for a personal result.

Sources and references

Written and checked by the MediHub editorial team against the sources above. Read how we build and review our calculators.

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Last updated . This calculator is for education only and is not medical advice. See the medical disclaimer.