Quick answer: With a period starting on 6 November 2026 and a 28-day cycle, ovulation is likely on 20 November and the fertile window runs from 15 to 20 November 2026; the most fertile days are 18 to 20 November.
How it's calculated
Ovulation usually happens about 14 days before the next period, because the phase after ovulation (the luteal phase) is fairly constant. So the likely ovulation day is the first day of the last period + cycle length − 14: 14 days after the period starts in a 28-day cycle (cycle day 15), 18 days after in a 32-day cycle.
You can conceive from intercourse on the day of ovulation or in the five days before it, since sperm survive up to five days and the egg about one day. Wilcox and colleagues (1995) found the chance of conception rises from about 10% five days before ovulation to about 33% on the day itself, so the last three days are the most fertile. Some calculators show a wider window, up to two days after the predicted ovulation, to allow for ovulation coming a little late.
The dates assume a regular cycle. If your cycles vary, the window moves with them; ovulation predictor kits, cervical mucus and basal body temperature show your own pattern. A home pregnancy test is most reliable from the day your next period is due.
Worked examples
- Period 6 November 2026, 28-day cycle: ovulation 20 Nov, window 15–20 Nov
- Period 6 November 2026, 32-day cycle: ovulation 24 Nov, window 19–24 Nov
Frequently asked questions
When am I most fertile?
In the two days before ovulation and on ovulation day. In a regular 28-day cycle that is about days 13 to 15, counting the first day of the period as day 1.
How long should we try before seeing a doctor?
Most couples conceive within a year. Doctors usually suggest a check-up after 12 months of trying, or after 6 months if the woman is 35 or older, or sooner if periods are very irregular.
Does this work with irregular cycles?
Only roughly. Use your shortest and longest recent cycles to see the range of possible fertile days, or use ovulation tests to find the day each cycle.
How long can sperm and the egg survive?
Sperm can live up to about 5 days in the body, while the egg lasts only 12 to 24 hours after ovulation. That is why the fertile window starts before ovulation.
Does this work after stopping the pill?
It may be less accurate at first, because cycles can take a few months to settle. Track a few periods and enter your average cycle length.
When can I take a pregnancy test?
Home tests are most reliable from the first day of your missed period, about two weeks after ovulation. Testing earlier can give a false negative.