How it works
Ovulation usually happens about 14 days before the next period. Since sperm can live up to 5 days, the fertile window runs from 5 days before to 1 day after ovulation.
Example
Period on October 1 with a 28-day cycle: ovulation around October 15 and a fertile window of October 10 to 16.
This is an estimate and not a birth control method. Talk to your doctor if you are trying to conceive or avoid pregnancy.
Frequently asked questions
What if my cycle is irregular?
Use the average of your last 6 cycles; predictions will be less accurate.
See also
Results are estimates for information only and are not financial, legal or medical advice. Rates, taxes and fees vary — confirm with a professional or your lender.