Ideal Weight Calculator
An ideal weight calculator estimates a healthy body weight range from your height and sex using four classic clinical formulas: Devine (1974), Robinson (1983), Miller (1983), and Hamwi (1964). All four share the same structure — a base weight for a height of 5 feet (152.4 cm) plus a fixed increment per additional inch — but differ in their coefficients, which is why they produce slightly different results for the same person.
These formulas were originally developed for medication dosing rather than aesthetics, and the Devine formula is still widely used in pharmacology today. Because they ignore muscle mass, bone density, and body composition, the results should be read as a reference range, not a target. Comparing the four estimates alongside the WHO healthy BMI range of 18.5-24.9 kg/m² gives a more complete picture of where a healthy weight lies for your height.
How it works
Each formula starts from a base weight at 152.4 cm (5 ft) and adds a fixed amount per inch (2.54 cm) above that. Devine: men 50 kg + 2.3 kg/inch, women 45.5 kg + 2.3 kg/inch. Robinson: men 52 kg + 1.9 kg/inch, women 49 kg + 1.7 kg/inch. Miller: men 56.2 kg + 1.41 kg/inch, women 53.1 kg + 1.36 kg/inch. Hamwi: men 48 kg + 2.7 kg/inch, women 45.5 kg + 2.2 kg/inch. For a 175 cm man, Devine gives 50 + 2.3 × 8.9 ≈ 70.5 kg.
Use cases
- Getting a science-based reference weight range before starting a diet or training plan
- Comparing Devine, Robinson, Miller, and Hamwi estimates to see how formulas differ for your height
- Cross-checking your goal weight against the WHO healthy BMI range of 18.5-24.9
- Understanding the ideal body weight figure used in clinical drug-dosing calculations
Frequently asked questions
How is ideal weight calculated by height?
The most common method is the Devine formula: 50 kg (men) or 45.5 kg (women) plus 2.3 kg for every inch of height above 5 feet (152.4 cm). A 170 cm woman would have an ideal weight of about 45.5 + 2.3 × 6.9 ≈ 61.4 kg. Robinson, Miller, and Hamwi use the same structure with different coefficients.
Which ideal weight formula is the most accurate?
No single formula is definitively best because none accounts for body composition. Devine is the standard in clinical medication dosing, Robinson tends to give values closest to the middle of the healthy BMI range, and Miller yields the highest estimates for short people. Health professionals usually treat the four results together as a plausible range.
Is ideal weight the same as a healthy BMI?
Not exactly, but they overlap. The WHO defines a healthy BMI as 18.5-24.9 kg/m², which for a 175 cm person spans roughly 57-76 kg — a range that contains most formula results. The formulas give a single point estimate, while BMI defines the boundaries of the healthy interval.
Why is my ideal weight different from what I weigh even though I'm fit?
The formulas only use height and sex, so they cannot distinguish muscle from fat. Athletes with high muscle mass often weigh more than their formula-based ideal weight while having low body fat. Measures like body fat percentage, waist circumference, or a DEXA scan describe body composition far better than any height-based formula.
What were the Devine and Hamwi formulas created for?
They were created for clinical use, not aesthetics. Hamwi published his rule in 1964 for quick bedside estimates, and Devine proposed his formula in 1974 to standardize drug dosing, since many medications are dosed by ideal rather than actual body weight. Both remain in use in pharmacology and nutrition today.