How to find your ovulation day
- Enter the first day of your last period.
- Enter your average cycle length (28 days if you're not sure).
- See your fertile window and ovulation day for the next three cycles.
How ovulation is estimated
Ovulation usually happens about 14 days before the next period. The calculator subtracts 14 days from your cycle length to estimate ovulation day.
The fertile window
You are most likely to conceive in the five days before ovulation and on the day itself. Having sex every one to two days in this window gives the best chance.
More precise methods
Ovulation test kits detect the hormone surge 24β36 hours before ovulation, and basal body temperature rises after it. Combining methods improves accuracy.
Frequently asked questions
When do I ovulate?
Usually about 14 days before your next period. In a 28-day cycle that is around day 14; in a 32-day cycle, around day 18.
What is the fertile window?
The five days before ovulation and the day of ovulation. Sperm can live up to five days, and the egg about one day.
What if my cycles are irregular?
Use your average cycle length, but the estimate will be less reliable. Ovulation tests can help pinpoint it.
Is my data stored?
No. Everything is calculated in your browser and nothing is saved or sent.