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Ideal Body Weight Calculator
Every “ideal weight” formula thinks muscle is a mistake — here's what they say, and what actually matters.
Add it to see where you sit in each range. It never changes the formula numbers.
Enter your height to see what the five classic formulas say your “ideal weight” is — and a healthy range that actually accounts for muscle.
Free. No signup. The tool's own usage events never include your exact height or weight; a share link encodes them into its URL.
These formulas are fitness-education estimates, not medical advice. “Ideal weight” varies with build, muscle, and individual health — talk to a professional for anything clinical.
Where these formulas come from
Almost none of these numbers were built to describe a healthy body. The formula most people quote as “ideal body weight” is Devine, published in 1974 — and it was created to standardise gentamicin antibiotic dosing by body size. It was a pharmacology convenience that got adopted as a general “ideal weight” almost by accident, and it was never derived from studying which weight is healthiest.
The others are cut from similar cloth. Robinson (1983) and Miller (1983) are refits of Devine against other reference data — same drug-dosing lineage, slightly different numbers. Hamwi (1964) is older still and started life as a 1960s bedside estimate of desirable body weight for diabetic patients. All four use only your height and sex, and all four trace back to clinical convenience, not health outcomes.
The one modern exception is Peterson (2016). It has no sex term and is derived to land you at a target BMI of 22 at any height — an actual body-composition anchor rather than a dosing table. It's the most defensible of the five, which is exactly why we flag it. But even Peterson is a height-only estimate, and no height-only formula can see how much muscle you carry.
The five formulas
All five run off your height (and, for four of them, your sex). Enter your height in the calculator above to put a real number next to each. Here's where each one actually came from.
| Formula | Year | What it was actually built for |
|---|---|---|
| Hamwi | 1964 | A 1960s bedside estimate of desirable body weight for diabetic patients — not from any study of healthy weight. |
| Devine | 1974 | Created to standardise gentamicin antibiotic dosing by body size. It became the default clinical IBW almost by accident; it was never a health target. |
| Robinson | 1983 | A refinement of Devine's dosing formula, refit to a reference dataset. Same drug-dosing lineage, slightly lower numbers. |
| Miller | 1983 | Another Devine refit from the same era, with a higher base and a gentler per-inch slope. Also a dosing tool at heart. |
| Peterson | 2016 | The modern one: derived to hit a target BMI of 22 at any height, with no sex term. The most defensible of the five because it's anchored to a real body-composition reference rather than a dosing table. |
Why they fail lifters
Take a real example: a man at 178 cm (5′10″) weighing 88 kg (194 lb) at 12% body fat. By any reasonable standard that's an athletic, lean, healthy body composition — 12% body fat is genuinely fit. Now run him through the tools everyone uses.
His BMI is about 27.8, which lands him in the “overweight” band. Every one of the five ideal-weight formulas puts his “ideal” between roughly 70 and 75 kg — so he's 13 to 18 kg “over ideal” by all of them. On paper, three different height-based methods agree he needs to lose a sixth of his bodyweight. In reality, he'd have to strip off most of the muscle he built to get there.
Nothing is wrong with the man; the tools are wrong for him. Every one of them works from height and weight alone and treats a kilogram of muscle exactly like a kilogram of fat. Muscle is denser and heavier for its size, so the more you train, the more these methods over-count your “excess” weight. For a lifter, being above “ideal” is usually a sign the method is broken, not the body.
A better frame: composition, not scale weight
The fix isn't a better single number — it's to stop asking for one. A healthy weight is a range, which is why the calculator shows the standard healthy-BMI band (18.5–24.9) next to the formulas. But no weight-for-height band, BMI or otherwise, can see how much of you is muscle — so widening the band wouldn't fix the real problem, it would just move the blind spot.
The question worth actually answering is what your weight is made of. A muscle-aware read doesn't come from a wider window on the scale — it comes from your body-fat percentage and your lean mass. Those tell you whether being “above ideal” means you're muscular or you have fat to lose, and those two situations call for opposite plans. From the calculator you can hand your height and sex straight to the Lean Body Mass Calculator or the Body Fat Calculator to measure composition directly.
Common mistakes with ideal weight
- Treating one formula's number as a target. These are rough, height-only estimates that disagree with each other by kilograms. Chasing any single one to the decimal is chasing false precision.
- Assuming “above ideal” means fat. If you lift, the extra weight over a formula's number is often muscle. The formula can't tell — only a composition measurement can.
- Cutting muscle to hit the scale number. Dieting down to a 1970s dosing formula's output, when you're already lean, usually means losing hard-won muscle for no health benefit.
- Trusting BMI and IBW to be different answers. They're the same height-and-weight logic run two ways, and they share the same blind spot to body composition.
- Ignoring build and frame. Bone structure and limb proportions vary; a broad, heavy-framed person and a slight one at the same height have different healthy weights, and a single formula can't capture that.
Methodology
The calculator renders all five classic formulas exactly as published. The four inch-based formulas (Devine, Robinson, Miller, Hamwi) take a base weight at 5 feet and add a fixed amount per inch above it; below 5 feet they lose their footing, so we floor the per-inch term at zero and say so rather than extrapolate into nonsense. Peterson (2016) is BMI-based and sex-free, derived to hit a target BMI of 22 at any height. Heights convert between centimetres and inches with the exact 2.54 factor so the outputs match the published reference values.
The healthy BMI range uses the standard 18.5–24.9 band applied to your height. We deliberately don't widen that band for lifters: no weight-for-height range can distinguish muscle from fat, so a muscle-aware read has to come from body composition — your body-fat percentage and lean mass — rather than a bigger window on the scale. This is a fitness-education tool, not medical advice; for anything clinical, talk to a qualified professional.
Everything runs in your browser. The tool's own usage events only ever send coarse buckets — your unit, sex, a bucketed height, and whether you entered a weight — never your exact height or weight. If you use the share button, your inputs are encoded into that link so the page can rebuild your result; that link then sits in your address bar like any other URL.
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What is ideal body weight?
Ideal body weight (IBW) is an estimate of a “healthy” weight for your height, from a formula that uses only height and sex. The catch: the classic formulas were built in the 1960s–1980s as clinical tools — mostly for standardising drug doses — not as health targets. They give one number, but a real healthy weight is a range that depends on your build and muscle.
Why do the formulas give different numbers?
They were fit to different datasets for different jobs. Devine (1974) was for antibiotic dosing; Robinson and Miller (1983) refit it; Hamwi (1964) began as a bedside estimate of desirable weight for diabetic patients; Peterson (2016) targets a BMI of 22. Each has its own base and per-inch slope, so they can differ by several kilos at the same height — a good reminder that none is “the” right answer.
Am I overweight if I'm above my 'ideal' weight?
Not necessarily — and if you lift, probably not. The formulas and BMI use height and weight alone, so they can't tell muscle from fat. Muscle is dense: a lifter reads “over ideal” while carrying a lean, healthy composition. Being above the number only matters if the extra weight is fat — so measure your composition, not the scale.
Which formula is the best one to use?
If you must pick one, Peterson (2016) is the most defensible: it's the only sex-free formula and it's anchored to a target BMI of 22 rather than a drug-dosing table. The older four are useful as context and a rough spread, but weren't built from health outcomes. Better yet, drop the single-number chase and use a healthy range plus your body composition.
Do these formulas work for athletes and lifters?
Poorly — which is the point of this tool. They were derived on general clinical populations, so they under-predict a healthy weight for anyone with trained muscle. A strength athlete can be above every formula's “ideal” and above the normal BMI band while lean and healthy — because every one of these methods is blind to muscle. Judge yourself on composition and performance, not a height-only estimate.
Should I cut down to hit my ideal weight?
No — not as a goal in itself. Cutting to force the scale onto a formula's number can cost you hard-won muscle, especially if you're already lean. Pick a body-composition goal instead — a target body-fat % or a lean-mass number to protect — and let your weight land where it lands. If you lose fat, do it slowly and keep training hard.
What's the difference between BMI and ideal body weight?
They're the same idea from two directions. BMI takes your weight and height and returns an index with bands; ideal body weight takes your height and returns the weight that lands in a healthy zone. Both use only height and weight, so neither sees composition. We show a BMI-based healthy range next to the formulas because a range is more honest than a single point — and both still need a composition check for a lifter.
Is it true these formulas came from drug dosing?
Yes, for most of them. Devine (1974) — the default clinical IBW — was published to standardise gentamicin dosing by body size; Robinson and Miller are refits of it; Hamwi began as a bedside estimate of desirable weight for diabetic patients. None of the four was derived from studying which weight is healthiest — they were clinical conveniences that drifted into fitness culture. Only Peterson (2016) used a body-composition reference. That origin is the best reason not to treat any of them as a personal target.
Chase composition, not a 1974 number
An 'ideal weight' formula can't see your muscle. Stronger tracks your lifts and lean progress so you build the body composition that actually matters — and watch the right numbers move.
