Body measurements Health Calculators

Adjusted Body Weight Calculator

The adjusted body weight calculator is a tool that helps estimate the weight of active lean body tissue, allowing for precise weight measurements and accurate estimation of nutritional needs.

Adjusted Body Weight Calculator

Ideal Body Weight (IBW) and Adjusted Body Weight (IjBW) are frequently used clinically to adjust drug dosing, help estimate renal function and the pharmacokinetics in morbidly obese patients. The most common IBW equation used is the Devine formula.

Actual body weight (ABW), body weight (BW), or simply standardised as weight in the literature, is defined as the measurement taken when the subject is able to stand unassisted using a calibrated scale. The subject should wear minimal clothing, and should also remove shoes and socks. Before starting, the scale should be zeroed and then the subject must stand in the centre of the scale, without support and with equal distribution of weight between both feet. Measurements should be taken to the nearest 0.1 kilogram (kg). To account for diurnal variation, the most accurate measurement is taken in the morning after voiding. When measured correctly, ABW can be used to compare with other anthropometric measurements, for example with height to calculate body mass index (BMI = weight/height2).

Adjusted body weight

Adjusted body weight (sometimes abbreviated to AjBW) is a measure used for calculating a person’s nutritional needs, popular among dietitians when they are tasked with setting up a weight loss program. It is especially useful when the patient is overweight or obese. As adipose tissue is less metabolically active than lean tissue, using actual body weight for calculating one’s energy requirements might result in some overestimations for people above their healthy BMI. Hence, it’s often recommended to use AjBW instead.

How to use the adjusted body weight calculator?

The adjusted body weight calculator will use your sex, height and weight to figure out your ideal weight, which is a component of the adjusted body weight formula. Please note that there are several accepted equations used for calculating ideal weight, based on slightly different scientific theories. However, the differences in results are practically negligible, so you shouldn’t worry about them. In this calculator, we use the Robinson formula.

To use our calculator, follow these instructions:

  • Provide the calculator with your sex.
  • Input your height.
  • Input your actual body weight.
  • The calculator will use the values you provided to calculate your AjBW and display it to you in the bottom-most field.

Estimated Ideal Body Weight (IBW) Formula

Male: 50 kilogram (kg) + 2.3 kg for each inch over 5 feet.

Female: 45.5 kg + 2.3 kg for each inch over 5 feet.

This formula only applies to persons 60 inches (152 cm) or taller.

Estimated Adjusted Body Weight (ABW) Formula

0.4 × (actual weight – IBW) + IBW

Examples

1. Calculate the IBW of a man who is 81 ½” (inches) tall and weighs 209 pounds (lb). If this man is obese (> IBW + 30%), calculate the ABW.

Male IBW = 45.5 kg + 2.3 × each inch over 60″
209 lb ÷ 2.2 = 95 kg
81.5″ – 60″ = 21.5″
50 kg + 21.5 x 2.3″
IBW = 99.45 kg
The man’s actual weight is less than IBW + 30% so it is not necessary to calculate the ABW.

2. Calculate the IBW of a man who is 64″ tall and weighs 70 kg. If this man is obese (> IBW + 30%), calculate the ABW.

Male IBW = 45.5 kg + 2.3 × each inch over 60″
64″ – 60″ = 4″
50 kg + 2.3 x 4″
IBW = 59.2 kg
The man’s actual weight is less than IBW + 30% so it is not necessary to calculate the ABW.

3. Calculate the ideal body weight (IBW) of a woman who is 64″ tall and weighs 80 kg. If this woman is obese (> IBW + 30%), calculate the ABW.

Female IBW = 45.5 kg + 2.3 × each inch over 60″
64″ – 60″ = 4″
45.5 kg + 2.3 x 4″
IBW = 54.7 kg
The woman’s actual weight is greater than the IBW + 30%, so calculate the ABW

ABW = 0.4 × (actual weight – IBW) + IBW
0.4 ×( 80kg – 54.7 kg) + 54.7 kg
ABW = 64.82 kg

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