Four classic ideal-weight formulas side by side, the healthy BMI band around them, and the honest history of where these numbers came from.
Your numbers
cm
Ideal weight — average of four formulas
70kg
at 175 cm — but read it as a range, not a target
Formula spread
68.7–72kg
lowest to highest formula
Healthy BMI range
56.7–76.6kg
BMI 18.5–25 at your height
Average as BMI
22.9kg/m²
where the formulas land
Four formulas at your heightHover a bar for its value. The healthy BMI range for your height spans 57–77 kg — every formula lands inside it.
Ideal weight vs height — with the healthy BMI envelope
BMI 25BMI 18.5DevineRobinsonMillerHamwi
The dashed gray lines are the edges of the healthy BMI range (18.5 and 25). The four formulas run through the middle of that band at every height — hover to compare.
All four formulas were built for drug dosing and clinical charts, not aesthetics. Frame size, muscle and age move a genuinely healthy weight by several kilograms in either direction.
Where “ideal weight” formulas come from
None of the four formulas in this calculator began as health advice. The oldest, Hamwi (1964), was a quick rule of thumb for clinicians estimating target weights in diabetic patients. The most famous, Devine (1974), was proposed for drug dosing— Dr. B.J. Devine needed a lean-body-size proxy to dose gentamicin safely, and formalized the folklore rule of “100 lb plus 5 lb per inch” into metric. Robinson and Miller both published revisions in 1983 after actuarial data suggested Devine ran heavy at some heights and light at others. Pharmacists still use Devine every day; diet culture adopted it for a purpose it was never validated for.
Devine (1974) Men: 50.0 + 2.3 kg/in over 5 ft Women: 45.5 + 2.3
Robinson (1983) Men: 52.0 + 1.9 kg/in over 5 ft Women: 49.0 + 1.7
Miller (1983) Men: 56.2 + 1.41 kg/in over 5 ft Women: 53.1 + 1.36
Hamwi (1964) Men: 48.0 + 2.7 kg/in over 5 ft Women: 45.5 + 2.2
Read the structure: a base weight at five feet, plus a fixed increment per inch. That linearity is the formulas’ deepest flaw — real healthy weight scales with the square of height (which is exactly what BMI encodes), so linear formulas drift light for tall people and heavy for short ones. It is also why they are undefined below five feet: at 152 cm they simply return their base value.
How the four compare
Formula
Built for
Tendency
Devine
Drug dosing (gentamicin, digoxin)
The clinical standard; middle of the pack
Robinson
Revision of Devine vs actuarial tables
Reads lightest for tall men
Miller
Same revision effort, different fit
Highest base, flattest slope — heaviest for short people
Hamwi
Bedside estimation, 1964
Steepest slope — heaviest for tall people
At most heights the four land within 4–8 kg of one another, and — as the chart above shows — all of them run through the middle of the healthy BMI band. That is the fairest way to read them: four opinions about the center of a range that modern evidence defines directly.
Frame size: the missing variable
The formulas assume an average skeleton. Real bone structure varies enough that two equally lean people of identical height can weigh 5–10 kg apart. Older clinical charts handled this with a ±10% adjustment for small or large frames, typically judged by wrist circumference: roughly, a wrist over 19 cm (7.5 in) in men or 16.5 cm (6.5 in) in women suggests a large frame, and the formula output should be read toward the top of its range. Muscle adds further spread on top — a formula cannot see whether your kilograms squat.
“Ideal” is a range, and always was
The strongest evidence we have does not identify an ideal weight at all — it identifies a band. Mortality and disease risk are lowest and roughly flat across a BMI of about 18.5 to 25, rising gradually outside it. For your height that band spans some 20+ kilograms; every formula on this page is just a point inside it. The healthy weight calculator shows the full band and where your current weight sits in it, and the BMI calculator covers the index behind it, including its limits for muscular and older people.
If you want a target with actual information in it, skip the formulas entirely and work from composition: a body fat percentage in a healthy range at a weight you can maintain beats any number a 1974 dosing equation can produce. Use the formula average the way a clinician does — as a rough center of gravity, not a verdict.
Frequently asked questions
What is my ideal weight for my height?+
By the classic formulas, roughly 2.3 kg (5 lb) per inch over 5 feet, on a base of 45–56 kg depending on formula and sex — about 68–75 kg (150–165 lb) for a 5'10" man, or 55–62 kg (121–137 lb) for a 5'5" woman. But the honest answer is a range: anything that puts your BMI between 18.5 and 25 counts as healthy, and where you personally belong inside it depends on frame and muscle.
Which ideal weight formula is most accurate?+
None of them is 'accurate' in a medical sense, because none was validated against health outcomes — Devine's was created for calculating drug doses. Robinson and Miller are gentler revisions of it; Hamwi is the oldest and heaviest-handed. Their average is as good a single number as any, and the healthy BMI range is the better-evidenced reference around it.
Why was the Devine formula invented?+
In 1974 Dr. B.J. Devine proposed it to estimate ideal body weight for dosing medications like gentamicin, whose safe dose scales with lean body size rather than total weight. It was never designed as a health or appearance target — it escaped into diet culture later. Clinical pharmacology still uses it daily for exactly its original purpose.
Does frame size change my ideal weight?+
Yes, meaningfully. Bone structure alone varies enough that two equally lean people of the same height can differ by 5–10 kg. Traditional charts adjusted the formula weight by roughly ±10% for small or large frames, often judged by wrist circumference or elbow breadth. This is one of the main reasons a single ideal number is fiction.
Why do the formulas differ for men and women?+
Women carry more essential fat and less muscle per unit height on average, so every formula uses a lower base weight and, in most cases, a smaller per-inch increment for women. Note the differences between formulas for women are larger than for men — evidence of how little solid data the originals were built on.
Should I try to reach my ideal weight?+
Treat it as a compass heading, not a finish line. If you are far above the healthy range, moving toward it has real, measurable health benefits — most of which arrive with the first 5–10% of weight lost. Chasing the last few kilograms to hit a formula's exact output has no evidence behind it, especially if you carry meaningful muscle.