Ideal Weight Calculator guide
See what the four classic ideal body weight formulas say for your height, how far apart they are, and the healthy BMI range that gives a more realistic target.
Four formulas, side by side
"Ideal body weight" (IBW) formulas all follow the same shape: a base weight at 5 feet tall, plus a fixed amount for every inch above that. They differ only in the numbers.
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/in; women 49 kg + 1.7 kg/in. Miller (1983): men 56.2 kg + 1.41 kg/in; women 53.1 kg + 1.36 kg/in. Hamwi (1964), originally in pounds: men 106 lb + 6 lb/in; women 100 lb + 5 lb/in.
The calculator runs all four, averages them, and adds the weight range that gives a BMI of 18.5-24.9, the healthy range used by the CDC and WHO. Seeing them together is the point: at the same height they can disagree by 10 lb or more, which tells you how rough any single "ideal" number is.
What these formulas were actually built for
None of them was designed as a personal weight goal. Hamwi's rule was a quick bedside estimate for dietitians. Devine published his in 1974 to calculate doses of the antibiotic gentamicin, and it is still used today to dose some drugs and to set ventilator volumes in intensive care (as "predicted body weight"). Robinson and Miller were 1983 attempts to refit Devine's shape to life-insurance weight tables.
A 2020 comparison in the Journal of the Intensive Care Society (Patel et al.) tabulated the formulas across heights and showed how far apart they drift, especially for tall men, where Hamwi runs heaviest and Miller lightest. None accounts for muscle mass, frame size, age, or ethnicity.
Worked example
A man 5'10" (70 inches) is 10 inches over 5 feet. Devine: 50 + 2.3 × 10 = 73.0 kg (160.9 lb). Robinson: 52 + 19 = 71.0 kg (156.5 lb). Miller: 56.2 + 14.1 = 70.3 kg (155.0 lb). Hamwi: 106 + 60 = 166 lb (75.3 kg). The spread is 155-166 lb. His healthy BMI range is about 129-174 lb, much wider than any formula suggests.
A woman 5'5" (65 inches): Devine 57.0 kg (125.7 lb), Robinson 57.5 kg (126.8 lb), Miller 59.9 kg (132.1 lb), Hamwi 125 lb. Healthy BMI range: about 111-150 lb.
Common mistakes
Treating the result as a target you must hit. A formula is a population average from half a century ago. Your healthy weight is a range that depends on muscle, health markers, and how you feel.
Applying it to muscular people. Athletes and lifters routinely weigh 15-25% above IBW with low body fat. Body fat percentage or waist-to-height ratio tells you more.
Using it below 5 feet. The formulas start at 5 ft (152 cm). Below that they subtract per inch and produce numbers that can be unrealistically low. The calculator warns you; rely on the BMI range instead.
Using it for children or during pregnancy. These are adult formulas. Children need growth charts; pregnancy needs weight gain guidance based on pre-pregnancy BMI.
Mixing units. The formulas count inches over 5 feet, so 5'10" is 10, not 5.10 or 70.
A better way to think about weight
Health risk tracks body fat distribution and fitness more than any scale number. A waist smaller than half your height, regular activity, and normal blood pressure, blood sugar, and cholesterol matter more than landing on a formula's output. If you are working toward a weight, the healthy BMI range gives you a wide, realistic target, and the TDEE and calorie deficit calculators help plan a sustainable pace.
If thinking about weight causes distress, or you find yourself restricting food heavily, please talk to a doctor or a registered dietitian. Your primary care provider can refer you to eating disorder specialists.
How we calculate: sources
Frequently asked questions
What is my ideal weight?
There is no single ideal weight. Classic formulas give a number within about 5-10 lb of each other, and the healthy BMI range (18.5-24.9) gives a wider, more realistic span for your height.
What is the Devine formula?
Men: 50 kg + 2.3 kg per inch over 5 feet. Women: 45.5 kg + 2.3 kg per inch over 5 feet. It was published in 1974 for drug dosing and is still used in hospitals.
Why do the formulas give different results?
Each was fit to different data in different decades: Hamwi (1964), Devine (1974), Robinson and Miller (1983). At the same height they can differ by 10 lb or more.
Do ideal weight formulas account for muscle?
No. They use only height and sex. Muscular people often weigh well above their formula result while having low body fat.
Can I use this if I am under 5 feet tall?
The formulas were designed for adults 5 feet (152 cm) and taller. Below that they extrapolate poorly, so rely on the healthy BMI range instead.
Is ideal body weight the same as healthy weight?
No. Ideal body weight is a clinical estimate for dosing and nutrition. Healthy weight is a range that depends on body composition, fat distribution, and health markers.
Is my data uploaded?
Everything runs in your browser. Nothing you enter is uploaded to a server or stored by us.
Which ideal weight formula is most accurate?
None is clearly best for individuals. Devine is the most used in medicine because of drug dosing history; the average of all four plus the healthy BMI range gives a more realistic picture.
What is the ideal weight for a 5'4" woman?
The four formulas give about 120-129 lb (Hamwi 120, Devine 121, Robinson 123, Miller 129). The healthy BMI range at that height is about 108-145 lb.