Updated September 2026 See your ideal weight range based on four published scientific formulas and a healthy BMI range.
About ideal weight formulas
The four formulas shown here were developed between the 1960s and 1980s, primarily for use in pharmacology to calculate drug doses based on lean body mass. They were not designed to prescribe aesthetic weight goals.
The Robinson (1983) formula is generally considered the most updated. The Devine formula (1974) is still widely used in clinical settings for medication dosing. The BMI range of 18.5–24.9 from the World Health Organization may be more practically relevant for health outcomes, though BMI doesn’t account for muscle mass or body composition.
Use these numbers as context, not targets. Two people at the same height can have different healthy weights based on frame size, muscularity, and genetics.
Where “ideal weight” formulas came from
This is the calculator that deserves the most caution, because its history explains its limits. The four formulas here all descend from a single 1974 paper by Dr B J Devine, who proposed an equation for calculating drug dosages — specifically, for estimating the volume of distribution of medications in patients whose weight was unknown. It was never intended to describe a healthy or desirable bodyweight.
Everything since has been a refinement of that pharmacological shortcut. Robinson, Miller and Hamwi each adjusted the coefficients against different reference populations, which is why they disagree with one another by several kilograms on the same person.
| Formula | Men | Women | Origin |
|---|---|---|---|
| Hamwi (1964) | 48.0 kg + 2.7 kg per inch over 5 ft | 45.5 kg + 2.2 kg per inch over 5 ft | Clinical nutrition, insulin dosing |
| Devine (1974) | 50.0 kg + 2.3 kg per inch over 5 ft | 45.5 kg + 2.3 kg per inch over 5 ft | Drug dosage estimation |
| Robinson (1983) | 52.0 kg + 1.9 kg per inch over 5 ft | 49.0 kg + 1.7 kg per inch over 5 ft | Revision of Devine against actuarial data |
| Miller (1983) | 56.2 kg + 1.41 kg per inch over 5 ft | 53.1 kg + 1.36 kg per inch over 5 ft | Alternative revision, flattest height response |
A worked comparison
A man of 178 cm (5 ft 10 in, so 10 inches over five feet):
Devine: 50.0 + (2.3 × 10) = 73.0 kg
Robinson: 52.0 + (1.9 × 10) = 71.0 kg
Miller: 56.2 + (1.41 × 10) = 70.3 kg
A spread of nearly five kilograms, from four equally published formulas, for the same man. That spread is the most useful thing this calculator tells you: there is no single ideal weight, and any site presenting one number to two decimal places is overstating what the arithmetic can support.
What these formulas cannot see
- Body composition. The central omission. Height and sex are the only inputs, so a muscular 178 cm man at 88 kg and 10 percent body fat is told he is 15 kg “overweight” while being leaner than nearly everyone he knows.
- Frame size. Skeletal width varies substantially between people of identical height, and none of these equations has a term for it.
- Age. Body composition shifts across decades at unchanged weight. A stable number can hide a real change.
- Ethnicity. All four were derived from largely Western reference populations, and healthy weight ranges differ across ancestries.
- What you actually want. “Ideal” here means statistically typical, not healthiest, strongest, or best for you.
Better questions to ask
If you want a target that means something, replace the question “what should I weigh?” with one of these:
- What is my waist-to-height ratio? Keep your waist under half your height. This captures central adiposity, which is the fat that carries cardiometabolic risk — and it classifies the muscular athlete and the low-muscle case correctly, which no weight-based formula can. More on this in why BMI fails and what to use instead.
- What is my body fat percentage? Pick a composition target, estimate your lean mass with our body fat calculator, and work out what you would weigh at your goal body fat. That figure is personal rather than population-derived.
- What weight can I actually maintain? The most practical question of the three. A weight you can hold while eating enough, sleeping well and training consistently beats a lower one you reach and lose.
How to use this page honestly
Read the four results as a range, not a target — roughly the weight band where a person of your height with average body composition tends to fall. If you sit above it and carry little muscle, it is a reasonable prompt to look at your calorie intake. If you sit above it and lift heavily, the formulas are simply describing someone who is not you.
Ideal weight — FAQ
Not necessarily. Ideal weight formulas represent statistical averages for a given height — they don’t account for your individual body composition, frame size, or athletic background. A competitive powerlifter, for example, might be well above the “ideal weight” for their height but have excellent health markers. Focus on body composition (body fat %) and health biomarkers rather than chasing a specific number on the scale.
Each formula was derived from a different study population and era. They agree closely for average heights but diverge at extremes. Rather than picking one “correct” answer, looking at the range across all formulas gives you a practical window. The overlap between formulas and the healthy BMI range is the most meaningful zone to target.
Because each was fitted against a different reference population for a different purpose — Devine for drug dosing, Hamwi for clinical nutrition, Robinson and Miller as later revisions. A four to five kilogram spread on the same person is normal and is the best evidence that no single ideal weight exists.
No. These formulas describe a statistically typical weight for your height and sex, with no information about body composition, frame size or health. A muscular person can be well above their “ideal” weight and considerably healthier than someone at it.
Waist-to-height ratio is the best single replacement — keep your waist under half your height. Pair it with a body fat estimate and a target weight derived from your own lean mass rather than a population average.
Yes, and none of these formulas account for it. Skeletal width varies meaningfully between people of the same height, which is one reason two people at identical heights can both be healthy several kilograms apart.