Estimated Fetal Weight Calculator

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Health Updated 14 Jun 2026

Estimated Fetal Weight Calculator is a health and wellness calculator that helps you calculate weight values or weight conversions between unit systems. The formula used is: Hadlock (1985): log₁₀(EFW) = 1.3596 − 0.00386·AC·FL + 0.0064·HC + 0.00061·BPD·AC + 0.0424·AC + 0.174·FL. Enter values using the units shown next to each input field (e.g. kg, cm, years).

Rates and fees change frequently. Always confirm the current figures with the official authority before relying on this result.
  • For information only — clinical assessment should be done by your sonographer.

Formula

Hadlock (1985): log₁₀(EFW) = 1.3596 − 0.00386·AC·FL + 0.0064·HC + 0.00061·BPD·AC + 0.0424·AC + 0.174·FL
  • Estimated Fetal Weight Calculator gives you a fast estimate using your inputs and updates instantly when you change any value.
  • Formula: Hadlock (1985): log₁₀(EFW) = 1.3596 − 0.00386·AC·FL + 0.0064·HC + 0.00061·BPD·AC + 0.0424·AC + 0.174·FL
  • Input definitions: • Biparietal Diameter (BPD): the numeric biparietal diameter (bpd) used in the calculation • Head Circumference (HC): the numeric head circumference (hc) used in the calculation • Abdominal Circumference (AC): the numeric abdominal circumference (ac) used in the calculation • Femur Length (FL): the numeric femur length (fl) used in the calculation
  • Manual method: write down each input, apply the formula step by step, then compare your manual result with the calculator output.
  • Enter values using the units shown next to each input field (e.g. kg, cm, years).
  • This calculator uses widely accepted health formulas and returns screening estimates only. It does not replace a diagnosis from a qualified healthcare professional.
  • Compare your result with published reference ranges. Values outside the normal range warrant a conversation with your doctor.
  • Practical tip: test a low, medium, and high scenario to understand sensitivity before making decisions.

Example Calculation

Inputs
  • Biparietal Diameter (BPD): 8.5 cm
  • Head Circumference (HC): 30 cm
  • Abdominal Circumference (AC): 30 cm
  • Femur Length (FL): 6.5 cm

Suppose you enter: Biparietal Diameter (BPD) = 8.5, Head Circumference (HC) = 30, Abdominal Circumference (AC) = 30, Femur Length (FL) = 6.5. The calculator applies the formula (Hadlock (1985): log₁₀(EFW) = 1.3596 − 0.00386·AC·FL + 0.0064·HC + 0.00061·BPD·AC + 0.0424·AC + 0.174·FL) and shows all output values below. Change any input field to immediately see how the result changes.

Frequently asked questions

What is the Estimated Fetal Weight?
The Estimated Fetal Weight Calculator is a health and wellness calculator that helps you calculate weight values or weight conversions between unit systems. Enter values using the units shown next to each input field (e.g. kg, cm, years).
When should I use this calculator?
Use this calculator whenever you need a quick, accurate result for weight values or weight conversions between unit systems without working through the arithmetic manually.
What units should I enter?
Enter values using the units shown next to each input field (e.g. kg, cm, years).
How accurate are the results?
This calculator uses widely accepted health formulas and returns screening estimates only. It does not replace a diagnosis from a qualified healthcare professional.
How do I interpret the result?
Compare your result with published reference ranges. Values outside the normal range warrant a conversation with your doctor.
How can I verify the calculation manually?
Use the displayed formula and work through the numbers step by step. If your manual result differs slightly, check rounding and unit conversions first.
Can I use this for planning and budgeting?
Yes. Run best-case, expected, and worst-case inputs to compare outcomes and make safer planning decisions.

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