Ideal Weight Calculator — 4 Formulas & Healthy Range

How this calculator works

The Devine formula, originally developed for medication dosing, is one of the most commonly cited reference formulas for ideal body weight. Each formula starts from a base weight at 5 feet (152.4 cm) and adds a fixed amount per inch above that:

• Devine (1974): men 50 kg + 2.3 kg per inch over 5 ft · women 45.5 kg + 2.3 kg per inch
• Robinson (1983): men 52 kg + 1.9 kg per inch · women 49 kg + 1.7 kg per inch
• Miller (1983): men 56.2 kg + 1.41 kg per inch · women 53.1 kg + 1.36 kg per inch
• Hamwi (1964): men 48 kg + 2.7 kg per inch · women 45.5 kg + 2.2 kg per inch

The frame option applies the common ±10% convention (originally used with the Hamwi method). This is a population reference, not a personal target — body composition and frame size vary widely.

By Suhaib Hassan · Reviewed 28 September 2026 against the original published formulas · How CalculatePilot verifies formulas →

Limitations of ideal weight formulas

These formulas don't account for muscle mass, bone structure, or individual body composition, so they're best treated as a general reference point rather than a personal goal. They were designed for adults around 5 ft and taller; below that they are less reliable.

A worked example

A man who is 180 cm tall: that's about 70.9 inches, or 10.9 inches over 5 feet. Using the Devine formula: 50 plus (2.3 times 10.9) equals about 75.0 kg, about 165 lb.

For a woman at the same height: 45.5 plus (2.3 times 10.9) equals about 70.5 kg, about 155 lb — illustrating the roughly 10 lb (4.5 kg) difference the formula applies between sexes at the same height.

Ideal weight in clinical use

Clinicians use ideal body weight — usually the Devine formula — for some medication doses and ventilator settings. When someone's actual weight is well above their ideal weight, an adjusted body weight (ideal weight + 0.4 × (actual − ideal)) is sometimes used instead. Medical information, not medical advice: dosing decisions are made by your healthcare team.

Sources

• Devine BJ. Gentamicin therapy. Drug Intell Clin Pharm 1974;8:650–655.
• Robinson JD, Lupkiewicz SM, Palenik L, et al. Determination of ideal body weight for drug dosage calculations. Am J Hosp Pharm 1983;40:1016–1019.
• Miller DR, Carlson JD, Loyd BJ, Day BJ. Determining ideal body weight. Drug Intell Clin Pharm 1983;17:673.
• Hamwi GJ. Therapy: changing dietary concepts. In: Diabetes Mellitus: Diagnosis and Treatment. American Diabetes Association, 1964.
• CDC — Adult BMI categories

Frequently asked questions

Is this formula still considered accurate?expand_more

It's a commonly used clinical reference, particularly for medication dosing, but it's a population average and doesn't account for individual differences in build or muscle mass.

Why do different ideal weight formulas give different results?expand_more

Each formula (Devine, Robinson, Miller, Hamwi) was derived from different population data and uses slightly different constants, so results typically vary by a few kilograms between formulas for the same height. None is definitively 'correct' — treat them as general reference points rather than precise targets.

Is BMI or ideal weight formula more useful?expand_more

Both have similar limitations — neither accounts for muscle mass or individual body composition, so pairing either with other measures like body fat percentage gives a fuller picture.

How does body frame size change ideal weight?expand_more

A common convention subtracts 10% for a small frame and adds 10% for a large frame. You can estimate your frame from your wrist circumference and height with the body frame size calculator.