How to use Pregnancy Due Date Calculator
- Choose whether you know your last period or the conception date.
- Enter the date (and your cycle length if it is not 28 days).
- Read the due date and gestational age.
About this tool
Naegele's rule estimates the due date as 280 days (40 weeks) after the first day of the last menstrual period, adjusted when your cycle is longer or shorter than 28 days. From a conception date, the due date is 266 days later. Only about 5% of babies arrive on the exact due date, and anywhere from 37 to 42 weeks is considered normal.
An ultrasound in early pregnancy gives a more accurate date than any calculation. This calculator gives general estimates from standard formulas and is not medical advice. Talk to a doctor or dietitian about your own health.
Frequently Asked Questions
- How many weeks is a full-term pregnancy?
- Full term is 39 to 40 weeks, and births from 37 to 42 weeks are considered term.
- Why might my doctor give a different date?
- Doctors may adjust the date using an early ultrasound measurement.
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