Adjusted Body Weight Calculator
Ideal, actual and adjusted weight for dosing.
Set by the drug's distribution into fat. Follow the specific agent's guidance.
This is arithmetic, not a prescribing decision. Dosing also depends on renal and hepatic function, the agent, the indication and monitoring.
Adjusted body weight
70.3 kg
Actual weight is at or below ideal, so adjusted body weight is not normally used — dose on actual weight unless the protocol says otherwise.
How the Adjusted Body Weight Calculator works
Some drugs distribute into fat tissue and some do not, so neither actual weight nor ideal weight is the right dosing basis for every medication in obesity. Adjusted body weight splits the difference, adding a fraction of the excess weight to the ideal figure.
Not medical advice. This calculator gives a general estimate, not medical advice. It cannot account for your individual health, medical history, or medication. Talk to a qualified healthcare professional before acting on any result.
Frequently asked questions
How is adjusted body weight calculated?
AdjBW = ideal body weight + 0.4 × (actual body weight − ideal body weight). The 0.4 factor is the most common, though 0.3 and 0.5 appear in some protocols depending on the drug's distribution into adipose tissue.
When is adjusted body weight used instead of actual weight?
For drugs that distribute only partially into fat — aminoglycosides are the classic example. Hydrophilic drugs are often dosed on ideal body weight, and highly lipophilic ones on actual weight. Always follow the specific drug's guidance rather than a general rule.
How is ideal body weight calculated here?
By the Devine formula: 50 kg + 2.3 kg per inch over 5 feet for men, and 45.5 kg + 2.3 kg per inch over 5 feet for women. It was devised in 1974 for exactly this purpose, drug dosing, rather than as a health target.
Is this calculator a substitute for clinical judgement?
No. Dosing depends on renal and hepatic function, the specific agent, the indication and monitoring, none of which a weight formula captures. This gives the arithmetic; the prescribing decision belongs to a qualified clinician.