Estimated Fetal Weight (Hadlock)
Ultrasound-based fetal weight estimate.
What is Estimated Fetal Weight (Hadlock)?
Ultrasound-based fetal weight estimate. Estimated Fetal Weight is intended for use in: Pregnant patients undergoing obstetric ultrasound.
How to Use the Estimated Fetal Weight Calculator
- Enter Biparietal diameter (BPD) in cm.
- Enter Head circumference (HC) in cm.
- Enter Abdominal circumference (AC) in cm.
- Enter Femur length (FL) in cm.
- Click Calculate to see your result and interpretation.
Formula & Version
This calculator uses formula version 1.0, last reviewed September 2026.
Clinical Considerations & Limitations
- Ultrasound-estimated fetal weight carries a typical error margin of ±15-20% — treat as an estimate, not a precise weight.
- The regression coefficients used here should be independently verified against the primary publication before clinical use.
References
- Hadlock FP et al., Radiology 1985;151:333-337
Frequently Asked Questions
What is Estimated Fetal Weight (Hadlock)?
Ultrasound-based fetal weight estimate.
Who is Estimated Fetal Weight intended for?
Pregnant patients undergoing obstetric ultrasound. Always confirm applicability to your specific patient before use.
What are the limitations of Estimated Fetal Weight?
Ultrasound-estimated fetal weight carries a typical error margin of ±15-20% — treat as an estimate, not a precise weight. The regression coefficients used here should be independently verified against the primary publication before clinical use.
What formula or reference does Estimated Fetal Weight use?
Hadlock FP et al., Radiology 1985;151:333-337
Is Estimated Fetal Weight a diagnosis?
No. Estimated Fetal Weight produces a score or estimate to support clinical decision-making — it is not a diagnosis and should be interpreted alongside full clinical judgement.
