Pregnancy Calculator
Estimate pregnancy from the last period date and cycle length. Use this free pregnancy calculator for fast, clear results with no signup required.
Pregnancy Calculator guide
What it is for
The Pregnancy Calculator provides a planning estimate from the information entered.
How it is calculated
Add 280 calendar days to the first day of the last menstrual period. The entered cycle length is not used in this due-date model.
Assumptions
It assumes the date and cycle length are known; real cycles and dates vary.
Example
For a last menstrual period beginning January 1, 2026, this model estimates October 8, 2026. A clinician may revise dating using examination or ultrasound.
Limitations
This is an educational estimate, not a diagnosis, treatment, or dosing instruction. Consult a licensed healthcare professional, particularly during pregnancy, with symptoms, or before changing health behavior.
Public source: ACOG: Due Date Calculator