Back to Tools
Conception Calculator
About the Conception Calculator
Estimate the likely date of conception from a due date or from the first day of your last period.
How to use the Conception Calculator
- Choose the Method: Known Due Date or Last Period (LMP).
- Enter the Given Date.
- Press Estimate Date.
Formula and method
Conception usually happens about 14 days after the last period starts (in a 28-day cycle), which is about 266 days before the due date.
Tips
- The result is an estimate. Ovulation timing varies from cycle to cycle.
Frequently Asked Questions
It gives a window of a few days. Only an early ultrasound can date a pregnancy more precisely.