Due Date Calculator

Estimate Your Baby's Arrival Date

Based on Naegele's rule, a standard method used by healthcare professionals, this calculator provides an estimated due date for a pregnancy. Simply enter the first day of your last menstrual period (LMP), and the tool will add 280 days (40 weeks) to estimate the delivery date.

The Formula Explained

Naegele's rule is a simple calculation: Estimated Due Date = First Day of LMP + 9 Months + 7 Days An even more straightforward way to think about it is: Estimated Due Date = First Day of LMP + 280 Days This assumes a regular 28-day menstrual cycle.

How to Use the Calculator

1. Last Period Date: Use the date picker to select the first day of your last menstrual period.
2. Calculate: The calculator will instantly display your estimated due date.

Real-World Example

A woman's last menstrual period started on June 10, 2024.

• Adding 280 days to this date results in an estimated due date of March 17, 2025.

Frequently Asked Questions (FAQ)

• How accurate is this calculator? This provides an estimate, not a guarantee. Only a small percentage of babies are born on their exact due date. An early ultrasound performed by a healthcare provider can often provide a more accurate dating.
• What if my cycle is longer or shorter than 28 days? If your cycle is consistently different from 28 days, the accuracy of this calculator decreases. Your doctor can provide a more precise estimate.
• Is this the same as the Pregnancy Calculator? Yes, this is a simplified version of our main Pregnancy Calculator, which also provides information about your current trimester and weeks of gestation.