What this tool does
An ovulation calculator estimates the days in your cycle when you are most likely to be fertile, based on your last period and average cycle length. It is widely used by people trying to conceive, as well as those who simply want to understand their cycle better.
How to use this tool
- Enter the first day of your last period.
- Enter your average cycle length.
- Read your estimated ovulation day and fertile window.
- Track across several cycles for better accuracy.
Why it matters
Understanding your fertile window can help with family planning. Because cycles vary naturally, this calculator gives an estimate rather than a guarantee, and it is best used alongside other methods and guidance from a health professional. This tool is not medical advice.