Conception Date Calculator
Estimate the most likely date of conception from your last period and cycle length.
Show solution steps
What is the Conception Date Calculator?
A conception date calculator estimates when conception most likely occurred, based on the fact that ovulation — and therefore the most fertile window — typically falls around the middle of a menstrual cycle, roughly 14 days before the next period is due. It's an estimate for personal reference, not a medical or legal determination, since actual ovulation timing varies between individuals and even cycle to cycle for the same person.
How to Calculate
Enter the first day of your last menstrual period and your average cycle length. The calculator estimates the likely conception date as your last period date plus (cycle length minus 14) days, with the realistic range spanning a few days on either side given natural cycle variation.
Formula
Conception ≈ LMP + (cycle length − 14) days
How to Use
- Enter your details in the fields above.
- The result updates instantly as you type.
- Use Copy, Print or Download PDF to save your result.