Ideal weight
calculator

Your "ideal" body weight from height and sex, by the four formulas people actually cite — Devine, Robinson, Miller, and Hamwi — side by side. Plus two things most ideal-weight calculators leave out: where three of these formulas came from, and the BMI healthy range they all sit inside. Imperial or metric.

There is no single "ideal weight." What this calculator gives you is four height-and-sex estimates — Devine, Robinson, Miller, and Hamwi — that a lot of clinical and fitness tools quote, shown together with the range they span, and overlaid on the WHO healthy-weight band for your height. For a 5'10" (178 cm) man the four formulas land between 155.0 and 166.0 lb (70.3–75.3 kg); the BMI-normal band for that height runs 128.9 to 174.2 lb (58.5–79.0 kg). The four "ideal" numbers are four points inside a band roughly four times as wide, which is the honest way to read them.

How the math works

Each formula anchors at 5 feet (60 inches) and adds a fixed amount of weight per inch above that. They differ only in the starting weight and the per-inch increment, and each has a separate line for men and women. Written out:

Hamwi is the odd one out: it was written in pounds (106 lb plus 6 lb per inch for men), so the calculator converts it with the exact 1 lb = 0.45359237 kg factor rather than a rounded coefficient. Below 5 feet all four extrapolate downward, subtracting per inch, and lose the validity they were built for — they were derived for adults at or above 5 feet.

Here is the part most calculators skip. Devine (1974) came out of a paper on gentamicin antibiotic dosing; Robinson (1983) and Miller (1983) were published in a hospital-pharmacy journal, Miller's specifically for digoxin dosing. They exist because many drugs are dosed against lean body mass, and a quick height-based proxy was needed at the bedside. "Ideal" here is a pharmacology term of art — the weight the dose math assumes — not a verdict on how a person should look. Only Hamwi (1964) came from nutrition, in a diabetes-management textbook chapter. That a 2026 fitness page still presents antibiotic-dosing math as your goal weight says more about how rarely these tools get revisited than about the formulas.

The four formulas at a glance

Worked example

Take a 5'10" (178 cm; 70 inches) man. Height over 5 feet is 10 inches, so each formula adds ten increments to its base:

• Devine: 50.0 + 2.3 × 10 = 73.0 kg (160.9 lb)
• Robinson: 52.0 + 1.9 × 10 = 71.0 kg (156.5 lb)
• Miller: 56.2 + 1.41 × 10 = 70.3 kg (155.0 lb)
• Hamwi: 106 + 6 × 10 = 166 lb (75.3 kg)
• Range across the four: 155.0–166.0 lb (70.3–75.3 kg); a spread of 11 lb (5.0 kg).

The WHO-normal weight band for that height — the weights at BMI 18.5 and 25 — is 128.9 to 174.2 lb (58.5–79.0 kg). All four "ideal" points sit comfortably inside it, clustered near the middle. Run a 5'5" (165 cm) woman and the pattern holds: Devine 125.7 lb, Robinson 126.8 lb, Miller 132.1 lb, Hamwi 125.0 lb (56.7–59.9 kg), inside a BMI band of 111.2–150.2 lb (50.4–68.1 kg). The formulas agree on a narrow number; the healthy range is much wider.

When this calculator is wrong

The same limit that breaks BMI breaks every formula here, and it's whole categories, not a rounding error: none of them can tell muscle from fat, because none of them take weight as an input at all — only height and sex. A 6'0" (183 cm) man gets the same "ideal" from Devine whether he is a sedentary office worker or a 200 lb (90.7 kg) lifter at 12% body fat — the formula never sees his weight. Run that muscular case through BMI and it reads 27.1 — "overweight" (25.0–29.9, WHO) — while that 12% body fat sits squarely in the athlete range (6–13%, ACE). Height-based "ideal weight" makes the same mistake one step earlier: it prescribes a number that a muscular build will and should exceed.

The counter-case is the general, non-athletic adult, which is exactly who BMI and these formulas were validated to screen. If you don't carry unusual muscle, the four-formula range and the BMI band both track your healthy weight well enough to be a useful reference — a first pass, not a target to chase to the pound. The misclassification bites at the edges: the heavily muscled read high, and people who've lost muscle can hit an "ideal" number while carrying too much fat for their frame. If the formula and the mirror disagree, measure body composition and trust that.

What to do with the result

Read the output as a range, not a goal weight. The four formulas give you a band and the BMI overlay gives you a wider one; a sensible reference weight for a general adult is somewhere in the overlap, adjusted for how much muscle you carry. If you're lean and muscular, expect to sit above the formula numbers and be fine. If you're setting an actual target, anchor it to something you can measure — body-fat percentage, waist circumference, how your lifts and energy hold up — rather than to a single line from a 1974 dosing equation.

Then, if a change is the point, that's a calorie-balance question, not an ideal-weight one. Use the range here to sanity-check the destination, then run your maintenance calories and a deficit or surplus to get there at a rate you can hold. Recompute the ideal-weight range only when your height reading changes — it doesn't move with your weight, which is the tell that it was never measuring your body composition in the first place.

Common questions

How do I calculate my ideal body weight?

Pick a formula, start from its 5-foot base weight, and add its per-inch increment for every inch you are over 5 feet. Devine for men is 50 kg plus 2.3 kg per inch: a 5'10" man is 50 + 2.3 × 10 = 73.0 kg (160.9 lb). Robinson, Miller, and Hamwi use the same shape with different numbers, which is why this calculator shows all four and the range they span.

Which ideal weight formula is most accurate?

None is "accurate" in the sense of measuring your body — they're height-and-sex estimates with no body-composition input. Devine (1974) is the most widely used because it became the clinical default for drug dosing, not because it's the most correct. The useful move is to read the four as a range and overlay the BMI healthy band, rather than trusting one number.

Why do the formulas give different answers?

They were derived by different authors for different purposes, so their base weights and per-inch increments differ. For a 5'10" man they spread from 155.0 lb (Miller) to 166.0 lb (Hamwi) — about 11 lb (5.0 kg). The spread is the point: it shows how much "ideal weight" depends on which equation you happen to use.

Is ideal body weight the same as a healthy weight?

Not quite. "Ideal body weight" is a single formula output; a healthy weight is a range. For a 5'10" man the four formulas cluster around 155–166 lb, but the WHO-normal band runs 128.9–174.2 lb (58.5–79.0 kg). Plenty of healthy weights sit outside the formula numbers, especially for muscular or larger-framed people.

Where do these formulas come from?

Three of the four are clinical-pharmacy equations for dosing drugs against lean body mass: Devine (1974) from gentamicin dosing, Robinson (1983) and Miller (1983) from a hospital-pharmacy journal, Miller's for digoxin. Hamwi (1964) is from a diabetes-management textbook. None was built as a body-image or fitness target — that use came later.

What should I use instead of ideal body weight?

For body composition, a body-fat estimate (tape, calipers, or DEXA) tells you the muscle-vs-fat split these formulas can't see. For a weight goal, work from maintenance calories and a rate you can sustain. The four-formula range is a fine sanity check on the destination; it's a poor target on its own.