Comprehensive Calculator Guide
This calculator works out two weights dietitians and pharmacists use: ideal body weight by the Devine formula and the adjusted body weight used with excess weight. A man 175 cm tall weighing 110 kg has an ideal weight of 70.5 kg and an adjusted weight of 86.3 kg, as he’s at 156% of ideal. It’s for information; doses and diet plans are for professionals.
Why adjust, and where Devine comes from
Many drugs distribute mainly in muscle and water, and fat burns less energy than muscle, so actual weight can overstate needs in obesity while ideal weight can understate them. Adjusted weight adds only 40% of the excess to ideal weight, typically used above 120–125% of ideal.
Ben Devine published his formula in 1974 for gentamicin dosing: 50 kg for men, 45.5 kg for women, plus 2.3 kg per inch over 5 feet. It isn’t a health target weight.
How to Use
- Choose sex and enter height.
- Enter actual weight.
- Press “Calculate” to see ideal weight, adjusted weight and your share of ideal.
Formula Used
IBW = 50 (men) or 45.5 (women) + 2.3 × (height in inches − 60) | AdjBW = IBW + 0.4 × (actual − IBW)
Practical Examples
- Example 1
- Man, 175 cm, 110 kg: IBW 70.5 kg, AdjBW 86.3 kg, 156% of ideal.
- Example 2
- Woman, 160 cm, 95 kg: IBW 52.4 kg, AdjBW 69.4 kg, 181% of ideal.
Important Tips
- Each drug has its own protocol for which weight to use.
Common Mistakes to Avoid
- Using adjusted weight as a weight-loss goal.
Frequently Asked Questions
- What is adjusted body weight?
- Ideal weight plus 40% of the excess above it, used in clinical nutrition and some doses.
- How is Devine ideal weight calculated?
- 50 kg (men) or 45.5 kg (women) plus 2.3 kg per inch over 152.4 cm.
- When is adjusted weight used?
- Usually when actual weight exceeds 120–125% of ideal, depending on the protocol.