Due Date Calculator

Calculate your pregnancy due date based on last menstrual period or conception date with week-by-week milestones.

Free to use
12,500+ users
Updated January 2025
Instant results

Due Date Calculator

Pregnancy tracker & planner

Calculate Your Due Date

Choose a calculation method and enter your date. Your due date is an estimate - only 5% of babies arrive exactly on their due date!

Calculation Method

Enter Date

The first day of your last menstrual period

Trimester Guide

About Pregnancy Dating

Why 40 weeks?

Pregnancy is measured from the first day of your last period, even though conception occurs about 2 weeks later. This is why pregnancy is 40 weeks (280 days) instead of 38 weeks from conception.

Due Date Accuracy:

Only about 5% of babies are born exactly on their due date. Most babies arrive between 37-42 weeks. Your healthcare provider may adjust your due date based on early ultrasound measurements.

Full Term Definitions:

  • • Early term: 37-38 weeks
  • • Full term: 39-40 weeks
  • • Late term: 41 weeks
  • • Post term: 42+ weeks