Calculadora de Peso Corporal Ajustado
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
PCA = PI + 0,4 × (real − ideal)
About this calculator
The Adjusted Body Weight Calculator helps healthcare professionals determine the adjusted weight for obese patients. The formula used is ABW = IBW + 0.4 × (actual_weight − IBW), where IBW is the estimated ideal body weight. This tool is especially useful for calculating correct medication dosages in obese individuals, preventing both underdosing and overdosing.
The adjusted weight calculation is based on the principle that adipose tissue does not metabolize drugs the same way as lean tissue. By using the formula, only 40% of the excess weight (difference between actual and ideal weight) is added to the ideal weight. This results in an intermediate value between ideal and actual weight, more appropriate for dose adjustments.
When to use this calculator? It is recommended for patients with a BMI above 30 kg/m² who require medications with a narrow therapeutic window, such as anesthetics, antibiotics, or chemotherapeutics. It is also useful in intensive care units and parenteral nutrition. Note that the formula does not apply to children, pregnant women, or athletes with high muscle mass.
Important precautions: the ideal weight must be calculated correctly, usually by the Devine formula (men: 50 kg + 2.3 kg per inch over 1.52 m; women: 45.5 kg + 2.3 kg per inch over 1.52 m). In patients with edema or ascites, the actual weight may be overestimated. Always consult a pharmacist or physician before adjusting doses based on adjusted weight.
Frequently asked questions
What is the difference between ideal body weight, actual weight, and adjusted body weight?
Ideal body weight is an estimate based on height and sex. Actual weight is the measured weight. Adjusted body weight is an intermediate value used for drug dosing in obese patients, accounting for different metabolism in adipose tissue.
When should I not use adjusted body weight?
Do not use in children, pregnant women, athletes with high muscle mass, or patients with significant edema/ascites. Also avoid for drugs that do not depend on body weight, such as some anticoagulants.
How do I calculate ideal body weight for the formula?
The most common formula is Devine: for men, 50 kg + 2.3 kg per inch over 1.52 m; for women, 45.5 kg + 2.3 kg per inch over 1.52 m. Other formulas like Hamwi also exist.
Can adjusted body weight be used for any medication?
No. It is mainly indicated for drugs with limited distribution into adipose tissue, such as anesthetics, some antibiotics, and chemotherapeutics. Consult the drug literature or a pharmacist.
What if the patient has a BMI below 30?
In that case, adjusted body weight is usually not needed. Use actual weight or ideal weight, depending on the drug and clinical recommendation.