Estimated Gestational Age and Fetal Weight Calculator
Enter fetal biometry (BPD, AC, HC, FL). The calculator outputs:
EFW using Hadlock 1–4 equations (log10 weight), and
GA (Menstrual Age, MA) using Hadlock 1984 equations that work with
single parameters or any available parameter combination.
Units can be entered in cm or mm; calculations internally use cm.
Outputs: EFW (g • kg • lb:oz) + GA (w+d)
Inputs
Biometry
EFW equations used (Hadlock; log10 weight)
Hadlock 1: log10(weight) = 1.304 + 0.05281*AC + 0.1938*FL - 0.004*(AC*FL)
Hadlock 2: log10(weight) = 1.335 - 0.0034*(AC*FL) + 0.0316*BPD + 0.0457*AC + 0.1623*FL
Hadlock 3: log10(weight) = 1.326 - 0.00326*(AC*FL) + 0.0107*HC + 0.0438*AC + 0.158*FL
Hadlock 4: log10(weight) = 1.3596 - 0.00386*(AC*FL) + 0.0064*HC + 0.00061*(BPD*AC) + 0.0424*AC + 0.174*FL
Hadlock 2: log10(weight) = 1.335 - 0.0034*(AC*FL) + 0.0316*BPD + 0.0457*AC + 0.1623*FL
Hadlock 3: log10(weight) = 1.326 - 0.00326*(AC*FL) + 0.0107*HC + 0.0438*AC + 0.158*FL
Hadlock 4: log10(weight) = 1.3596 - 0.00386*(AC*FL) + 0.0064*HC + 0.00061*(BPD*AC) + 0.0424*AC + 0.174*FL
Notes: Inputs are converted to cm before calculation. Weight is returned in grams (10log10).
GA equations used (Hadlock 1984 Table 1; Menstrual Age, MA in weeks)
BPD: MA = 9.54 + 1.482*(BPD) + 0.1676*(BPD^2)
HC: MA = 8.96 + 0.540*(HC) + 0.0003*(HC^3)
AC: MA = 8.14 + 0.753*(AC) + 0.0036*(AC^2)
FL: MA = 10.35 + 2.460*(FL) + 0.170*(FL^2)
BPD, AC: MA = 9.57 + 0.524*(AC) + 0.1220*(BPD^2)
BPD, HC: MA = 10.32 + 0.009*(HC^2) + 1.3200*(BPD) + 0.00012*(HC^3)
BPD, FL: MA = 10.50 + 0.197*(BPD*FL) + 0.9500*(FL) + 0.7300*(BPD)
HC, AC: MA = 10.31 + 0.012*(HC^2) + 0.3850*(AC)
HC, FL: MA = 11.19 + 0.070*(HC*FL) + 0.2630*(HC)
AC, FL: MA = 10.47 + 0.442*(AC) + 0.3140*(FL^2) - 0.0121*(FL^3)
BPD, AC, FL: MA = 10.61 + 0.175*(BPD*FL) + 0.2970*(AC) + 0.7100*(FL)
HC, BPD, FL: MA = 11.38 + 0.070*(HC*FL) + 0.9800*(BPD)
HC, AC, FL: MA = 10.33 + 0.031*(HC*FL) + 0.3610*(HC) + 0.0298*(AC*FL)
HC, AC, BPD: MA = 10.58 + 0.005*(HC^2) + 0.3635*(AC) + 0.02864*(BPD*AC)
BPD, HC, AC, FL: MA = 10.85 + 0.060*(HC*FL) + 0.6700*(BPD) + 0.1680*(AC)
HC: MA = 8.96 + 0.540*(HC) + 0.0003*(HC^3)
AC: MA = 8.14 + 0.753*(AC) + 0.0036*(AC^2)
FL: MA = 10.35 + 2.460*(FL) + 0.170*(FL^2)
BPD, AC: MA = 9.57 + 0.524*(AC) + 0.1220*(BPD^2)
BPD, HC: MA = 10.32 + 0.009*(HC^2) + 1.3200*(BPD) + 0.00012*(HC^3)
BPD, FL: MA = 10.50 + 0.197*(BPD*FL) + 0.9500*(FL) + 0.7300*(BPD)
HC, AC: MA = 10.31 + 0.012*(HC^2) + 0.3850*(AC)
HC, FL: MA = 11.19 + 0.070*(HC*FL) + 0.2630*(HC)
AC, FL: MA = 10.47 + 0.442*(AC) + 0.3140*(FL^2) - 0.0121*(FL^3)
BPD, AC, FL: MA = 10.61 + 0.175*(BPD*FL) + 0.2970*(AC) + 0.7100*(FL)
HC, BPD, FL: MA = 11.38 + 0.070*(HC*FL) + 0.9800*(BPD)
HC, AC, FL: MA = 10.33 + 0.031*(HC*FL) + 0.3610*(HC) + 0.0298*(AC*FL)
HC, AC, BPD: MA = 10.58 + 0.005*(HC^2) + 0.3635*(AC) + 0.02864*(BPD*AC)
BPD, HC, AC, FL: MA = 10.85 + 0.060*(HC*FL) + 0.6700*(BPD) + 0.1680*(AC)
Notes: GA/MA outputs are shown as weeks + days. Inputs are converted to cm.
“Best GA” uses the computed Hadlock MA equation with the lowest SEE available for your entered parameters.
Results
Enter measurements and click Calculate
Mean of available EFW equations
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Range: —
Best GA (Hadlock MA; lowest SEE available)
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—
BPD —, AC —, HC —, FL —
| Equation | Inputs needed | GA for this equation (w+d) | log10(weight) | EFW (g) | EFW (kg) | EFW (lb:oz) |
|---|---|---|---|---|---|---|
| No calculations yet. | ||||||
GA by available parameter combinations (Hadlock 1984)
| Combination | Inputs needed | MA (w+d) | SEE (weeks) |
|---|---|---|---|
| No GA calculations yet. | |||
“Best GA” selects the lowest SEE among computed equations.
Clinical caveats
- Ultrasound EFW has intrinsic error; interpret with the full clinical picture.
- Biometry-based GA is an estimate; accuracy varies with gestational age and measurement technique.
- This tool is for education/clinical support and does not replace clinical judgment.
References
Hadlock FP et al. Sonographic estimation of fetal weight. The value of femur length in addition to head and abdomen measurements. Radiology. 1984;150(2):535–540.
Hadlock FP, Deter RL, Harrist RB, Park SK. Estimating fetal age: Computer-assisted analysis of multiple fetal growth parameters. Radiology. 1984;152:497–501.
Hadlock FP, Deter RL, Harrist RB, Park SK. Estimating fetal age: Computer-assisted analysis of multiple fetal growth parameters. Radiology. 1984;152:497–501.