Calculate your fertile window and most likely conception dates.
Note: This calculator provides estimates only. Consult with your healthcare provider for medical advice.
Based on your cycle information
Your highest chance of conception
Most likely day of ovulation
Enter your menstrual cycle details and click "Calculate Fertile Window" to see results.
Use our Conception Calculator to estimate the likely date of conception based on the first day of your last menstrual period or your estimated due date.
A Conception Calculator helps estimate when conception likely occurred. While not an exact science, it provides a useful approximation for expecting parents or those tracking fertility.
Conception typically occurs about 11 to 21 days after the first day of the last menstrual period. If your menstrual cycle is regular (28 days), conception is most likely around day 14.
Estimated Conception Date = LMP + 14 days
OR
Estimated Conception Date = Due Date - 266 days
If your last period started on January 1st, your estimated conception date would be around January 15th.
The actual date of conception can vary depending on ovulation timing and other factors. This tool provides a general estimate and should not replace medical advice.