Ideal Body Weight Calculator
Calculate ideal body weight using the Devine, Hamwi and Robinson formulas — alongside the healthy BMI range, which is what clinicians actually use for individuals.
E.g., 5'10" = 70 inches
Healthy Weight Range
128.9 lbs – 173.5 lbs
BMI 18.5–24.9 for your height
26.5
Your BMI
160.9 lbs
Devine Formula
166.0 lbs
Hamwi Formula
156.5 lbs
Robinson Formula
A healthy weight for your height spans 128.9 lbs to 173.5 lbs — a range, not a target. You are 11.5 lbs above the top of that range. The three formulas average 161.2 lbs, which is 23.8 lbs below your current weight. Those formulas were built for drug dosing rather than health targets, so treat them as reference points, not goals.
Analysis & insights
Across the four standard formulas, your ideal weight averages 161.1552181333333 lbs (Devine 160.9374498, Hamwi 166, Robinson 0). That's 23.844781866666693 lbs above your current weight. These formulas give a starting point but don't account for muscle, frame size, or body composition — combine with BMI, waist circumference, and overall health markers for the complete picture.
Modest gap from ideal
23.844781866666693 lbs above ideal. Achievable through ~6-12 months of moderate habit changes.
Risk & benchmark gauge
Current band
Modest gap
+23.844781866666693 lbs from ideal
Industry benchmarks
- Average of formulas161.1552181333333 lbs
- Devine (medical)160.9374498 lbs
- Hamwi (1964)166 lbs
- Robinson (1983)0 lbs
- Gap from current+23.844781866666693 lbs
Key insights
"Ideal" formulas are guidelines
Devine, Hamwi, Robinson, and Miller formulas were developed for medical drug-dosing in the 1960s-80s. They give a reasonable target range but don't account for muscle mass, frame size, or ethnicity.
BMI is often a better screen
For most adults, "healthy weight" = BMI 18.5-24.9. The ideal-weight formulas give a single number; BMI gives a range. Both have limits for muscular or larger-framed people.
Body composition trumps the scale
A 175-lb person at 12% BF is healthier than a 165-lb person at 28% BF — even though the lighter person is closer to "ideal" weight. Track waist circumference and lean mass alongside scale weight.
Recommended actions(2)
Resistance train 2-3x per week
Medium priorityLifting preserves (during loss) or builds (during gain) muscle mass — the metabolically active tissue that keeps your maintenance calorie needs high.
Hit 0.7-1g protein per lb bodyweight
Medium priorityCritical for muscle preservation during weight loss and muscle gain during a surplus.
Related Calculators
This tool is for informational purposes only and does not constitute medical advice. Consult a healthcare professional for advice specific to your situation.
What is Ideal Body Weight?
The phrase "ideal body weight" is doing a lot of unearned work. The formulas that produce it — Devine, Hamwi, Robinson — were not designed to tell you what to weigh. They were built to standardise clinical calculations, principally drug dosing, where a single reproducible number is more useful than an accurate one.
B.J. Devine published his in 1974 for aminoglycoside antibiotic dosing. It has no published derivation from health outcomes at all; he proposed it, it was convenient, and it stuck.
They remain useful as reference points, and they are genuinely used in medicine — ventilator tidal volumes are still set from predicted body weight. As a personal target they are much weaker than the healthy BMI range, which is why this page leads with the range.
The most important thing any of these numbers omits is body composition. Two people of the same height and weight can have very different amounts of muscle and fat, and that difference matters more to health than the number on the scale.
The formula — how to calculate Ideal Body Weight
- over 5 ft
- = all three are anchored at 60 inches and extended upward — none is valid below it
- Frame adjustment
- = ±10% for small or large frame; this comes from Hamwi and is not part of the other two
The BMI range gives a span of roughly 30 to 40 pounds for a typical adult height. That width is not imprecision — it is the honest answer, because a single healthy weight does not exist.
Step-by-step example
- 01A 5'10" (70-inch) man.
- 02Devine: 50 + 2.3 × 10 = 73 kg, or 161 lb.
- 03Hamwi: 106 + 6 × 10 = 166 lb.
- 04Robinson: 52 + 1.9 × 10 = 71 kg, or 156.5 lb.
- 05Average: about 161 lb.
- 06Healthy BMI range for the same height: 18.5 to 24.9 works out at 129 to 174 lb.
- 07So the formulas land near the upper-middle of a 45-pound healthy range. Someone at 172 lb is inside the healthy range and 11 lb "over" their Devine weight — which tells you how little the word "ideal" means here.
What these formulas are actually for
They exist because some clinical calculations need a weight that does not vary with body fat.
Drug dosing is the main one. Many medications distribute through lean tissue rather than fat, so dosing a very heavy patient on actual weight risks toxicity. Using a predicted weight from height gives a consistent, reproducible basis.
Ventilator settings are the other well-known use. Lung volume scales with height, not with weight, so tidal volume is set from predicted body weight — a practice that came out of trials showing lower volumes reduce lung injury.
In both cases the point is standardisation, not health. Nobody claims a patient should weigh their Devine weight. The formula just has to give the same answer every time for the same height.
That history is worth knowing because it explains why the formulas look the way they do: a flat base at 5 feet plus a linear term per inch. Real human body mass does not scale linearly with height — it scales closer to the square, which is exactly what BMI captures and these formulas do not.
Below 5 feet these formulas break down
All three are anchored at 60 inches and extended upward only. Applied below that, the per-inch term goes negative and the results become nonsense — Devine returns about 49 lb for a 4-foot adult. If you are under 5 feet, ignore the formulas entirely and use the BMI range, which is valid at any height.
Why a range beats a target
The healthy BMI band of 18.5 to 24.9 spans roughly 30 to 45 pounds depending on height. People often read that width as vagueness. It is the opposite — it is precision about the actual state of the evidence.
Mortality and morbidity data show a broad flat region rather than a single optimum. Within the healthy range, moving a few pounds either way is not associated with meaningfully different outcomes. The curve only starts to bend well outside it.
A single "ideal" number invites a precision that the underlying biology does not support, and it converts a wide zone of perfectly good outcomes into a target you are either hitting or failing.
The other reason to prefer a range: it accommodates the variation these formulas cannot see. Frame size, muscle mass, bone density and the distribution of fat all shift where in the range an individual sits healthily.
Where BMI itself falls short
BMI is better than the IBW formulas for this purpose, and it is still a blunt instrument. It was devised by Adolphe Quetelet in the 1830s as a population statistic, and he explicitly said it was not for assessing individuals.
It cannot distinguish muscle from fat. A well-trained athlete frequently registers as overweight or obese by BMI while carrying very little fat. This is the most cited criticism and the most straightforward.
It says nothing about fat distribution, which matters considerably. Visceral fat around the organs carries substantially more metabolic risk than subcutaneous fat, and two people with identical BMI can differ sharply on that.
It also performs differently across populations. Risk thresholds for people of South Asian descent, for instance, are commonly set lower — several health bodies use 23 rather than 25 as the overweight threshold — because cardiometabolic risk rises at a lower BMI.
And it is a poor guide in older adults, where a slightly higher BMI is often associated with better outcomes, partly because unintended weight loss signals illness.
- Waist circumference —
- a better single indicator of metabolic risk than either BMI or IBW. Commonly cited thresholds are above 40 inches for men and 35 for women, with lower cut-offs for some populations.
- Waist-to-height ratio —
- keeping your waist under half your height is a simple and surprisingly robust screen that works across heights and populations.
- Body fat percentage —
- measures what actually matters, but accurate measurement needs DEXA or hydrostatic weighing; consumer scales using bioelectrical impedance are unreliable enough to be misleading.
- Adjusted body weight —
- a clinical variant, IBW + 0.4 × (actual − IBW), used for dosing certain drugs in patients with obesity. Another sign these are dosing tools rather than health targets.
What to do with the number
Use the BMI range as a rough orientation, and treat anything inside it as fine.
If you are outside it, the direction and the size of the gap matter more than the exact figure. Being a few pounds over the top of the range is not the same kind of information as being fifty pounds over it.
Waist measurement is worth taking alongside weight, because it captures the fat distribution that weight alone misses and needs nothing more than a tape measure.
Trends matter more than snapshots. Weight fluctuates by several pounds across a day and a week from hydration, food volume and hormonal cycles. A weekly average tells you far more than any single morning.
And if the goal is changing body composition rather than weight, the scale will actively mislead you. Gaining muscle while losing fat can leave weight flat for months while everything that matters improves.
Common mistakes to avoid
- Treating an ideal body weight formula as a health target. It was built for drug dosing.
- Applying the formulas below 5 feet, where they are not defined.
- Reading the healthy BMI range as imprecision rather than as the honest answer.
- Using BMI alone for a muscular athlete, where it systematically misclassifies.
- Ignoring waist circumference, which captures risk that weight does not.
- Weighing daily and reacting to normal fluctuation instead of tracking a weekly average.
- Chasing a number on the scale when the actual goal is body composition.
Frequently asked questions
Sources & references
Written and fact-checked by the CalcProLabs Editorial Team. Read our calculation methodology and editorial policy.
Last updated