How to Find Your Ovulation Date (2026)

Ovulation — the release of an egg from the ovary — typically happens once per cycle and marks the brief window in which conception is possible. Knowing when it occurs lets you time intercourse to maximise the chance of pregnancy, or track your cycle for any other reason. The Ovulation Calculator estimates your fertile window instantly from your last period date and average cycle length.

How to Calculate Your Ovulation Date

Ovulation does not happen on a fixed calendar day — it happens a consistent number of days before your next period. For most women, the luteal phase (from ovulation to the next period) is 14 days, give or take a day. That means you can estimate ovulation by working backwards from your expected next period date.

The formula is straightforward:

Estimated ovulation date = First day of last period + (Cycle length − 14)

For example, if your last period started on 1 June and your average cycle is 28 days, your next period is due around 29 June. Counting back 14 days gives an estimated ovulation date of approximately 15 June.

Ovulation Day and Fertile Window by Cycle Length

Sperm can survive in the reproductive tract for up to five days, so the fertile window extends a few days before ovulation as well as on the day itself. The table below shows estimated ovulation and fertile window ranges for common cycle lengths, assuming a luteal phase of 14 days. Cycle day 1 is always the first day of your period.

If your cycle length varies month to month, use your average over the last three to six cycles for a more reliable estimate.

Signs That Confirm Ovulation Is Approaching

Calendar estimates are a good starting point, but physical signs sharpen the prediction. Cervical mucus typically becomes clear, slippery, and stretchy — often described as similar to raw egg white — in the one to three days before ovulation. Basal body temperature (BBT) rises by about 0.2–0.5 °C immediately after ovulation and stays elevated for the rest of the cycle; tracking BBT each morning before getting up confirms ovulation has occurred, though it lags by a day. Ovulation predictor kits (OPKs) detect the LH surge that precedes egg release by 24–36 hours, making them the most actionable real-time indicator. Irregular cycles make calendar predictions less reliable, so combining at least two methods improves precision.

Use the Ovulation Calculator to get your estimated ovulation date and fertile window based on your last period and typical cycle length — no account required, all calculations happen in your browser.