Gestational Age by Ultrasound

Summary

Enter one or more ultrasound biometry measurements to instantly estimate gestational age in weeks and days, plus your estimated due date.

How it works

1. Select the ultrasound measurement type: CRL (Crown-Rump Length), BPD (Biparietal Diameter), FL (Femur Length), or HC (Head Circumference).
2. Enter the measurement value in millimeters.
3. Optionally set the ultrasound exam date and click "Calculate Gestational Age".
4. View the estimated due date (EDD), computed from your exam date plus the remaining gestational days.
5. Switch between measurement types to compare estimates from different biometry parameters.
6. Note the trimester range to confirm the selected measurement type is appropriate.

Use cases

• Confirm gestational age when last menstrual period is uncertain.
• Cross-check LMP-based dating against ultrasound biometry.
• Estimate due date from first-trimester CRL measurements.
• Calculate gestational age from second or third trimester BPD, FL, or HC.
• Support clinical documentation for obstetric care records.
• Educate patients about what their ultrasound measurements mean.
• Use as a quick reference tool in prenatal appointments.

Frequently Asked Questions