Pregnancy Due Date Calculator

First Day of Last Period

Estimated Due Date

Based on standard 40-week calculation (Naegele's rule).

What is a Pregnancy Due Date Calculator?

A Pregnancy Due Date Calculator estimates your baby's expected delivery date based on the first day of your last menstrual period (LMP). This tool uses Naegele's rule, the standard method used by healthcare providers worldwide.

The calculation is based on:

40-Week Pregnancy: Standard pregnancy duration from LMP
Naegele's Rule: Add 7 days to LMP, then subtract 3 months
Estimated Date: Provides an approximate delivery window

It's important to note that only about 5% of babies are born exactly on their due date. Most babies are born within two weeks before or after the estimated due date. This calculator provides an estimate, but your healthcare provider will use ultrasound measurements and other factors to determine a more precise due date during your prenatal care.

Frequently Asked Questions

The due date is an estimate. Only about 5% of babies are born exactly on their due date. Most are born within two weeks before or after.

If you're unsure, your healthcare provider can use an ultrasound to estimate your due date based on the baby's size and development.

The calculator works best with regular 28-day cycles. If you have irregular periods, consult your healthcare provider for a more accurate estimate using ultrasound.