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Ask four different clinicians what a 5-foot-8 man "should" weigh and you might get four different answers — and that's not because anyone's wrong, it's because there are several respected formulas, each built for a slightly different purpose. This Ideal Weight Calculator runs your height through all of them at once. For that 5-foot-8 man, the Devine formula suggests about 154 pounds, Robinson lands near 149, Miller around 152, and Hamwi close to 160 — a spread of roughly 11 pounds that shows there's no single magic number, only a sensible range.
All four share a design: a base weight for the first 5 feet of height, plus a fixed increment for every inch above that. The Devine formula, created in 1974 to help dose medications, starts men at 50 kilograms and adds 2.3 kilograms per inch over 5 feet, with women starting at 45.5 kilograms. Robinson's 1983 revision nudged the base and increments slightly lower to better fit observed data. Miller's version, also from 1983, uses smaller per-inch additions. Hamwi, the oldest at 1964, was built for quick bedside estimates and tends to give the highest figures. Because they use different constants, they diverge more the taller you are.
Consider a woman who is 5 feet 4 inches tall — that's 4 inches over the 5-foot base. Under Devine, her ideal weight is 45.5 kilograms plus 4 times 2.3 (9.2 kilograms), totaling 54.7 kilograms or about 121 pounds. Robinson gives her 49 kilograms plus 4 times 1.7, landing near 56 kilograms or 123 pounds. Miller's smaller increment produces roughly 122 pounds, while Hamwi's larger step yields about 130. The four results cluster between 121 and 130 pounds, and any weight inside that band is reasonable — which is exactly how these formulas are meant to be read, as a corridor rather than a target.
Enter your height and sex and the tool displays all four estimates side by side, plus a healthy-weight range derived from BMI for comparison. Don't fixate on a single formula; look at where the numbers overlap and treat that overlap as your practical range. These equations were originally built around medium frames, so if you have a notably small or large bone structure, expect your comfortable weight to sit toward the low or high end. To ground the result in your actual body, compare it with a body fat percentage reading and your BMI score, since two people at the same "ideal weight" can carry very different amounts of muscle.
These formulas were never meant to define a beauty standard or a hard goal. They exist mainly because clinicians need a quick reference for medication dosing, ventilator settings, and nutritional planning, and the clinical literature on ideal body weight treats them as estimates, not prescriptions. If your weight sits above the calculated range but your body fat is low and your bloodwork is healthy, the formula is simply failing to account for your muscle. Use the range as one input among several — activity level, how you feel, and objective health markers all count for more than matching a 60-year-old equation to the pound.
There's no single winner. Devine is the most widely used in medicine because of its dosing history, but Robinson and Miller often track modern data a bit better. The smartest move is to read all four as a range rather than crowning one.
They were built from height alone, decades before body-composition testing was common. That's their biggest limitation, and it's why a lifter can weigh well above the "ideal" figure while being extremely lean and healthy.
They lose accuracy at the extremes because the per-inch increments were calibrated on average heights. Someone 6 feet 6 inches or 4 feet 10 inches should treat the output as a loose ballpark and lean on other markers.
It's easy to dismiss a 1974 formula as obsolete, but the Devine equation quietly runs through modern hospital care every day. Many drug doses — particularly for anesthesia, chemotherapy, and antibiotics that distribute mainly through lean tissue — are calculated against ideal body weight rather than actual weight, because dosing a very heavy patient by their scale weight could deliver a toxic amount. Ventilator tidal volumes are set the same way, since lung size tracks height, not girth. That's the real reason these equations survive: they were built to answer a narrow clinical question — how much lean mass would a person of this height typically carry — and for that job they remain good enough that swapping them out would disrupt decades of established protocols. Understanding that origin story reframes your result. It was designed for a pharmacist's bench, not a bathroom mirror, which is exactly why you should read it as a reference point rather than an aspiration.
Once you've got your four-figure corridor, the practical question is what to do with it. Start by locating where you sit now relative to the range, then set a realistic pace rather than a deadline. Losing or gaining half a pound to a pound a week is sustainable and preserves muscle; anything faster tends to strip lean tissue or pile on fat. If you're 20 pounds above your corridor, that's a five- to ten-month project, not a crash diet — and framing it that way is what keeps people from quitting in week three. Weigh the range against how you feel and perform, too. If reaching the low end would leave you constantly hungry and weak in the gym, the high end of the corridor is probably the smarter home for your body. The formulas point you toward a neighborhood; your energy, strength, and health markers pick the house.
A healthy weight is a range you live in, not a number you hit once. Cross-reference this result with our calorie calculator to plan how to reach or hold it, browse the rest of our health calculators, or return to the full calculator directory for the complete toolkit.
Medical disclaimer: This ideal weight tool is for informational and educational purposes only and is not medical advice. The Devine, Robinson, Miller, and Hamwi formulas are historical clinical estimates that ignore muscle mass and frame size. Consult a licensed healthcare provider before setting a weight target or making changes to your diet or exercise. See our full Disclaimer.