Clinical calculator

Body Weight Reference Calculator

A transparent adult calculation aid for ideal body weight, percent IBW, BMI, and adjusted/nutritional body weight when selected criteria are met.

Inputs

Height
Actual body weight
Optional weight historyAdd previous/usual weight only when available.

Leave blank to omit Weight History from results and chart-note draft.

Unit

Percent weight change is a calculation aid and does not diagnose malnutrition. Interpret with intake, NFPE, fluid status, disease context, and institutional criteria.

Results

Enter valid inputs to calculate

Required adult inputs must pass entry guardrails before RDCalc shows body weight reference outputs.

Using Devine · 0.25 factor · BMI ≥30 or ≥130% IBW trigger

Chart-note draft

Draft text is provided for RD review and should be edited before use in clinical documentation.

Enter valid inputs to generate draft chart-note text.

Formula details

Show the math

These are the formulas and display rules used for the current result. Calculations are rounded only for displayed outputs and chart-note text.

Selected method formula

Devine

  • Male: 50 kg + 2.3 kg × inches over 5 ft.
  • Female: 45.5 kg + 2.3 kg × inches over 5 ft.
  • Below 5 ft: subtract 2.3 kg per inch below 5 ft.

Reference outputs

Percent IBW and BMI

  • %IBW = actual body weight ÷ selected IBW/reference weight × 100.
  • BMI = actual body weight ÷ height(m)².
  • BMI is contextual and does not assess body composition or fluid status.

Rounding

Display behavior

  • Weights display to 1 decimal kg and 1 decimal lb.
  • BMI displays to 1 decimal.
  • Percent IBW displays to the nearest whole percent.

Comparison formulas

Pro comparison rows use the implemented adult reference formulas below when available.

  • Hamwi: male 106 lb + 6 lb/in over 5 ft; female 100 lb + 5 lb/in over 5 ft.
  • Robinson: male 52 kg + 1.9 kg/in over 5 ft; female 49 kg + 1.7 kg/in over 5 ft.
  • Miller: male 56.2 kg + 1.41 kg/in over 5 ft; female 53.1 kg + 1.36 kg/in over 5 ft.
  • Lemmens/BMI 22: 22 × height(m)².
  • BMI target weights: target BMI × height(m)² for fixed targets 18.5, 22, 25, and 30.
  • Peterson target BMI: 2.2 × target BMI + 3.5 × target BMI × (height m − 1.5).
  • Configurable target BMI: target BMI × height(m)² using exact BMI algebra.

BMI target weights are reference/target weights only, not recommendations. For adult heights below 5 ft, linear methods use negative inches-over-5-ft; verify appropriateness against clinical judgment and local policy.

Adjusted/Nutritional Body Weight

selected IBW/reference weight + correction factor × (actual weight − selected IBW/reference weight)

Selected correction factor
—
Selected trigger
—

Current visibility reason

Valid inputs are needed before adjusted/nutritional body weight criteria can be evaluated.

Transparency

Sources & assumptions

Review the formula basis, configurable assumptions, and professional-scope limits before using outputs in documentation.

Available body weight reference methods

  • Devine remains the free/default method.
  • Hamwi, Robinson, Miller, Lemmens/BMI 22, fixed BMI target weights, Peterson target BMI, and configurable target BMI are available as Pro methods when access is active.
  • Peterson target BMI uses the Peterson et al. AJCN 2016 universal body-weight equation and is distinct from exact BMI target calculations.
  • Configurable target BMI uses exact BMI algebra: target BMI × height(m)².
  • Height may be entered as ft/in or cm; cm is converted using 1 inch = 2.54 cm.
  • BMI target weights are reference/target weights only and are not recommendations or prescriptions.
  • For adult heights below 5 ft, Hamwi, Robinson, and Miller use negative inches-over-5-ft; verify appropriateness against clinical judgment and local policy.

Adjusted/nutritional body weight basis

  • Formula: selected IBW/reference weight + correction factor × (actual body weight − selected IBW/reference weight).
  • 0.25 is the nutrition-focused default correction factor used by this calculator.
  • 0.4 is available as an alternate/common clinical factor; verify appropriateness against local protocol.
  • Trigger settings and correction factors may vary by institution.

Adult clinical scope

This calculator is intended for adult clinical nutrition use. It is not designed for:

  • Pediatrics
  • Pregnancy
  • Amputations
  • Major fluid shifts, edema, or ascites where actual weight may be clinically misleading
  • Cases requiring institution-specific protocols not represented in the calculator

Calculation caveats

  • Formula selection, adjustment factors, thresholds, and rounding practices may vary by institution.
  • BMI is provided as a contextual reference and does not distinguish between lean mass, fat mass, fluid status, or body composition.

Optional Weight History

  • Percent weight change = (current actual weight − previous/usual weight) ÷ previous/usual weight × 100.
  • Previous/usual weight uses the same adult entry guardrail as actual weight: 50–1000 lb or 22.7–453.6 kg.
  • Weight-history calculations are documentation aids and do not diagnose malnutrition.
  • Percent weight change should be interpreted with intake history, NFPE findings, fluid status, disease context, and institutional criteria.

Professional-use notes

Professional-use caution

For use by qualified healthcare professionals. This calculator is a calculation aid and does not replace clinical judgment.

This is not a nutrition prescription or treatment recommendation.

Verify results against local policy and clinical judgment before using outputs in clinical documentation.