Fertility & ovulation tools
Estimate when ovulation and the fertile window are most likely to occur. These are calendar-based estimates, not confirmation that ovulation happened.
Fertility calculators
Use both views together: one focuses on the ovulation date, the other on the wider fertile window.
How calendar estimates work
The calculators estimate ovulation as about 14 days before the next expected period. The fertile window is shown as the five days before ovulation through the day after. This reflects general biology: sperm can survive for several days in the reproductive tract, while an egg is viable for roughly 12–24 hours.
These estimates work best for people with fairly regular cycles. Ovulation can happen earlier or later than predicted, and it can vary from cycle to cycle even when periods are regular. Calendar estimates do not confirm that ovulation occurred.
If you are trying to conceive
Tracking several cycles, noticing cervical mucus changes, or using ovulation tests may give you more information. If you have been trying to conceive for 12 months without success — or 6 months if you are 35 or older — consider talking with a healthcare professional. They can assess factors that a calculator cannot.
For a closer look at body signs and test limitations, read ovulation signs and your fertile window.
Not a contraceptive method
Do not use calendar-based predictions to prevent pregnancy. They cannot reliably identify the days when conception is impossible, and they do not account for cycle variation. Talk with a healthcare professional about contraception that fits your needs.