Typical cycle
Fertile window of opportunity: April 16, 2026 to April 22, 2026
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Fertility window calculator
Calculate the fertile window around ovulation as a date range within the cycle.
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Calculator
Related guide: Understanding pregnancy weeks, ovulation and fertile days
Examples
Typical calculations
Longer cycle
Fertile window of opportunity: April 13, 2026 to April 19, 2026
Load this exampleShorter cycle
Fertile window of opportunity: April 16, 2026 to April 22, 2026
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Frequently asked questions
What are fertile days?
This is the time window around ovulation when pregnancy may be more likely.
Why does the window start before ovulation?
Sperm can survive in the body for several days.
Why does the window after ovulation end?
The egg cell can only be fertilized for a short time, so a short follow-up period is often taken into account.
Is the estimate equally good for all cycles?
No. If the cycle length fluctuates, the estimate becomes more uncertain.
Is the calculator suitable for contraception?
No. It is not safe enough for this and is only used for orientation.
What are the chances of getting pregnant on fertile days?
For healthy couples, the probability per cycle is roughly 20 to 30 percent, with the highest value on the two days before ovulation.
How many fertile days does a woman have per cycle?
Realistically, it's about five to six days: the days before ovulation plus the day of ovulation itself, because sperm survive for several days.
Does the estimate become more accurate with cycle observation?
Yes. Anyone who observes several cycles with basal temperature and cervical mucus can narrow down the fertile window much more precisely than with pure calendar calculation.
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Sources and notes
Rule status and context
- methodology
- Fertile window = approximately 5 days before to 1 day after ovulation.