- Enter weight in kg and height in cm. BMI, BSA, ideal body weight, and adjusted body weight all recompute live as you type.
- Choose sex — this sets the waist-circumference risk target and the Devine ideal-body-weight base (50 kg for men, 45.5 kg for women).
- Optionally enter waist circumference for central-adiposity context, and a target BMI (or use the quick-set buttons: 22, 23, or 25) to see the corresponding goal weight and how far it is from current weight.
- Use the cutoff toggle to read BMI against Asian-Pacific bands, Western WHO bands, or both side by side. The BMI number is identical; only the risk category changes.
- Read the Ideal & Adjusted Body Weight panel for the Devine (Western) and BMI-22 (Asian-Pacific) estimates, the % of IBW, and adjusted body weight for patients above ideal weight — the figures used for protein and drug dosing.
All computation runs in your browser; no values are stored or transmitted.
When to Use
Use this tool whenever a single set of anthropometric numbers is needed for a clinical decision: estimating body mass index against the correct cutoff for an Asian-Pacific patient, deriving body surface area for drug or chemotherapy dosing, or obtaining ideal and adjusted body weight to drive a protein prescription or weight-based medication dose. It is especially relevant in CKD, where protein targets (g/kg) and many drug doses are normalized to a body weight that should usually be the ideal or adjusted weight rather than the actual weight in an over- or underweight patient.
Appropriate population
Adults of Asian-Pacific ancestry (including Filipinos) for whom BMI risk categories are shifted lower than the Western WHO bands, and any adult needing BSA for dosing or IBW/AdjBW for nutrition and pharmacologic calculations. Particularly useful in CKD when setting g/kg protein and energy targets, since these should be referenced to ideal or adjusted body weight.
When NOT to rely on it
BMI does not distinguish muscle from fat and overestimates adiposity in very muscular people while underestimating it in sarcopenic or fluid-overloaded patients — use waist circumference and clinical judgment alongside it. In significant edema, ascites, or amputation, weight-based outputs (BMI, IBW %, AdjBW) are distorted; use dry weight where available. Devine IBW is undefined below 152 cm (5 ft) and is an estimate, not a measured value. These are educational aids, not a substitute for individualized assessment.
Pearls & Pitfalls
Use the right weight as your denominator
Protein targets in CKD (g/kg) and many weight-based drug doses should reference ideal or adjusted body weight, not actual weight, in obese patients — otherwise the prescription is systematically too high. Adjusted body weight is the usual compromise above ideal weight.
The cutoff changes the conversation
A Filipino patient with a BMI of 24 reads "normal" on a Western chart but "overweight" on the Asia-Pacific scale. Pair BMI with waist circumference (central adiposity) for a fuller risk picture rather than relying on the BMI number alone.
Pitfalls
(1) BMI mislabels very muscular and sarcopenic patients — it measures mass, not body composition. (2) Edema, ascites, and fluid overload inflate weight-based outputs; use dry weight in dialysis. (3) Devine IBW is an estimate and is undefined below 152 cm; treat it as a starting point, not a measured truth. (4) BSA-based dosing still requires checking the drug's own renal-adjustment rules in CKD.
Why Use It
In Asian-Pacific populations, the metabolic and cardiovascular risk that Western charts assign at BMI 25 and 30 appears roughly two units earlier, so the same number that reads "normal" by the Western WHO scale can already mean "overweight" or "obese" by the WHO Asia-Pacific scale. Choosing the right cutoff changes the conversation about weight for a Filipino patient. At the same time, body surface area underpins safe drug and chemotherapy dosing, and ideal/adjusted body weight is the correct denominator for protein and many weight-based medication doses in CKD — using actual weight in an obese patient overestimates the dose. Computing all four metrics from one set of inputs keeps these linked decisions internally consistent.
BMI, BSA & Body Weight Calculator
Enter your measurements once — BMI, Body Surface Area, Ideal Body Weight, and Adjusted Body Weight all calculate together. Uses WHO Asia-Pacific cutoffs for Filipinos.
Enter weight and height above to see IBW and AdjBW.
For education only. Discuss your numbers and any weight-loss plan with your nephrologist before changing diet, medications, or activity, especially if you are on dialysis or have advanced CKD. IBW and AdjBW guide protein prescriptions and drug dosing — confirm with your nephrologist or dietitian.
Next Steps
Use the result to support — not replace — clinical judgment.
- Interpret the value against the targets shown in the calculator and the Evidence section below, in the context of the full clinical picture.
- Trend serial measurements rather than acting on a single result; confirm abnormal or unexpected values before changing management.
- Apply the relevant KDIGO / specialty-guideline threshold and document the indication.
- Escalate or refer to nephrology when results are out of range, rapidly changing, or discordant with the clinical picture — and discuss the implications with the patient.
Evidence & References
Formula & Equations
| Quantity | Equation |
|---|---|
| Body mass index (kg/m²) | Weight (kg) ÷ [Height (m)]² |
| Body surface area — Mosteller (m²) | √[ Height (cm) × Weight (kg) ÷ 3600 ] |
| Ideal body weight — Devine, men (kg) | 50 + 2.3 × (height in inches − 60) |
| Ideal body weight — Devine, women (kg) | 45.5 + 2.3 × (height in inches − 60) |
| Ideal body weight — Asian-Pacific (kg) | 22 × [Height (m)]² (BMI-22 target weight) |
| Adjusted body weight (kg) | IBW + 0.4 × (actual weight − IBW), applied when actual weight > IBW |
| % of ideal body weight | (Actual weight ÷ IBW) × 100 |
| Target weight for a goal BMI (kg) | Target BMI × [Height (m)]² |
BMI risk cutoffs
| Category | Asian-Pacific (WHO WPRO) | Western (WHO) |
|---|---|---|
| Normal | 18.5–22.9 kg/m² | 18.5–24.9 kg/m² |
| Overweight | 23.0–24.9 kg/m² | 25.0–29.9 kg/m² |
| Obese | ≥ 25.0 kg/m² | ≥ 30.0 kg/m² |
Devine height in inches = height (cm) ÷ 2.54. The Devine equation is defined for heights ≥ 60 inches (152 cm); below that it returns its base value. Adjusted body weight uses a 0.4 correction factor and is intended for over-ideal-weight patients when dosing drugs and protein.
Evidence & References
The Asian-Pacific BMI cutoffs follow the WHO Expert Consultation, which concluded that many Asian populations carry elevated cardiometabolic risk at BMI values below the conventional Western thresholds. Body surface area uses the Mosteller equation, a simplified square-root formula validated against earlier BSA methods. Ideal body weight uses the Devine formula, originally derived for weight-based aminoglycoside dosing and still the most widely used IBW estimate; adjusted body weight applies a correction factor for patients above ideal weight.
- WHO Expert Consultation. Appropriate body-mass index for Asian populations and its implications for policy and intervention strategies. Lancet. 2004;363(9403):157–163.
- Mosteller RD. Simplified calculation of body-surface area. N Engl J Med. 1987;317(17):1098.
- Devine BJ. Gentamicin therapy. Drug Intell Clin Pharm. 1974;8:650–655. (Origin of the Devine ideal body weight formula.)
