Health

Due Date by Ultrasound Calculator

Free online due date ultrasound calculator. Calculate accurate results instantly with our easy-to-use tool.

Ultrasound Date

Weeks Gestation

Days Gestation

Estimated Due Date

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Method

How this calculator works

Due Date = Ultrasound Date + (280 days - Gestational Age in days)

Enter the exact date you had your ultrasound.
Enter the Gestational Age (weeks and days) you were given at that ultrasound.
The calculator projects exactly when you will reach 40 weeks (280 days).

Examples

Worked examples

Real numbers, end-to-end results.

Ultrasound Date: Feb 1, Gestation: 8 Weeks 2 Days

Due Date: Sep 12

Based on 40 weeks (280 days) total.

Use cases

When to use it

Get a more accurate due date after your dating scan.
Recalculate your due date if your doctor adjusts it based on an ultrasound.

Disclaimer: This calculator provides estimates for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider for decisions affecting your health. Results depend on the accuracy of inputs provided.

FAQ

Frequently asked questions

Why is ultrasound dating more accurate?

Early ultrasounds (first trimester) measure the Crown-Rump Length (CRL) of the fetus, which grows at a very predictable rate, making it more accurate than dating by Last Menstrual Period (LMP).

What does Gestational Age mean?

Gestational age is the age of the pregnancy, measured in weeks and days. A full-term pregnancy is typically 40 weeks.