Conception Date Calculator
Calculate possible conception dates and fertile window based on due date or pregnancy timing
About this calculator
The Conception Date Calculator helps determine when conception likely occurred based on your due date or current pregnancy stage. This tool calculates your fertile window and possible conception dates by working backwards from pregnancy milestones. It's particularly useful for family planning, medical appointments, or understanding your pregnancy timeline. The calculator uses standard pregnancy duration of 280 days from last menstrual period to provide accurate estimates for conception timing and your most fertile days.
How to use
Enter your due date or current pregnancy week into the calculator. The tool will automatically calculate and display your estimated conception date range and fertile window. You can also input your last menstrual period date for more precise results and conception timing estimates.
Frequently asked questions
How accurate is the conception date calculator?
The calculator provides estimates within a 2-3 day range. Actual conception can vary due to individual cycle differences and sperm survival time.
Can I use this if I have irregular periods?
Yes, but results may be less precise. The calculator works best with regular 28-day cycles but still provides helpful estimates.
What's the difference between conception date and due date?
Conception date is when fertilization occurred, typically 2 weeks after your last period. Due date is 40 weeks from your last menstrual period.