Pregnancy Due Date Calculator
Enter the first day of your last menstrual period (LMP) to calculate your estimated due date, how far along you are, and your trimester.
This calculator uses Naegele’s rule (LMP + 280 days). Your doctor may adjust your due date based on ultrasound measurements in the first trimester.
Everything runs in your browser — nothing is sent to any server. All free tools
Frequently Asked Questions
How accurate is a due date based on LMP?
Due dates from LMP are estimates. Only about 5% of babies are born on their exact due date. Ultrasound dating in the first trimester (especially 8-12 weeks) is more accurate.
What if my cycles are irregular?
Naegele’s rule assumes a 28-day cycle. If your cycles are shorter or longer, your doctor will adjust using ultrasound measurements.