Statistical
Devine weight, an adjusted-weight example and predicted body weight
Compare distinct weight equations with explicit units and assumptions; demonstrate why similarly named estimates should not be substituted blindly.
Separate the model from the clinical decision
The Devine equation uses a baseline of 50 kg for the M equation or 45.5 kg for the F equation, plus 2.3 kg per inch above 60 inches. This adult teaching worksheet supports heights of at least 60 inches only; shorter inputs return Outside example scope instead of silently clamping height to five feet. M/F select the historical equation coefficients, and unknown codes must not default to F.
An adjusted-weight calculation adds a chosen fraction of the difference between actual and calculated weight. The 0.4 factor in B6 is an illustrative input, not a recommendation for all medicines or people with obesity. This example applies only when actual weight is at least the calculated Devine weight. Selection of a dosing weight depends on the specific drug and protocol.
Predicted body weight for ventilation is calculated separately here using the centimetre coefficient 0.91 and baseline height 152.4 cm. This is close to, but not numerically identical to, 2.3 kg per inch. The 6 mL/kg multiplication is an arithmetic illustration, not a ventilator prescription or a complete ARDS protocol; actual settings require clinical assessment and monitoring. These estimates are not personal healthy-weight targets.
| Calculation | M equation at 70 inches, actual 110 kg | F equation at 64 inches |
|---|---|---|
| Devine weight | 73.0 kg | 54.7 kg |
| Adjusted example with factor 0.4 | 87.8 kg | Requires actual weight |
| PBW using 0.91 kg/cm | 73.114 kg before rounding | 54.7456 kg before rounding |
| Illustrative 6 mL/kg of unrounded PBW | 439 mL rounded | 328 mL rounded |
Devine equation in kilograms
Height is in inches. The supported example domain begins at 60 inches; this guard is an explicit limitation, not a modified Devine formula.
=IF(OR(NOT(ISTEXT(B2)),AND(UPPER(B2)<>"M",UPPER(B2)<>"F"),NOT(ISNUMBER(B3))),"Invalid inputs",IF(B3<60,"Outside example scope",ROUND(IF(UPPER(B2)="M",50,45.5)+2.3*(B3-60),1)))Adjusted weight with an explicit factor
The formula uses the unrounded Devine expression internally and validates the chosen factor between zero and one. Actual weight below that estimate is outside this example; no dosing decision is made.
=IF(OR(NOT(ISTEXT(B2)),AND(UPPER(B2)<>"M",UPPER(B2)<>"F"),NOT(ISNUMBER(B3))),"Invalid inputs",IF(B3<60,"Outside example scope",IF(OR(OR(NOT(ISTEXT(B2)),AND(UPPER(B2)<>"M",UPPER(B2)<>"F"),NOT(ISNUMBER(B3))),COUNT(B4,B6)<>2),"Invalid inputs",IF(OR(B4<=0,B6<0,B6>1),"Invalid inputs",IF(B4<(IF(UPPER(B2)="M",50,45.5)+2.3*(B3-60)),"Outside example scope",ROUND((IF(UPPER(B2)="M",50,45.5)+2.3*(B3-60))+B6*(B4-(IF(UPPER(B2)="M",50,45.5)+2.3*(B3-60))),1))))))Predicted body weight using the centimetre convention
Convert inches to centimetres with 2.54 and retain the unrounded result in B7. Different rounded coefficients can give small differences from the Devine result.
=IF(OR(NOT(ISTEXT(B2)),AND(UPPER(B2)<>"M",UPPER(B2)<>"F"),NOT(ISNUMBER(B3))),"Invalid inputs",IF(B3<60,"Outside example scope",IF(UPPER(B2)="M",50,45.5)+0.91*(B3*2.54-152.4)))Illustrative volume multiplication
Multiply the unrounded PBW by 6 mL/kg and round the result to whole millilitres. This does not configure a ventilator.
=IF(COUNT(B7)<>1,"Invalid inputs",ROUND(6*B7,0))Try the example
Use the original values or change them to test your understanding.