The ideal weight calculator below runs your height and gender through four different clinical formulas β Devine, Robinson, Miller, and Hamwi β plus the standard healthy-BMI weight range, so you can see how much these "ideal weight" numbers actually agree with each other. Spoiler: they don't agree by much.
Arb Digital built this as a free, no-signup tool. There's no perfect single number for your ideal weight, but comparing several respected formulas side by side gives you a far more honest picture than any one of them alone.
What This Ideal Weight Calculator Does
It takes your height, gender, and frame size and runs four separate formulas that were each originally developed for different clinical purposes β mostly to estimate safe medication dosing in hospitals, not to define beauty or fitness standards. It also calculates the weight range that corresponds to a "normal" Body Mass Index (18.5 to 24.9), the range used by health agencies worldwide. The result is a spread of numbers, not one β because that's a more accurate representation of reality than a single figure ever could be.
How to Use It
- Choose your units. Toggle between inches and centimeters.
- Enter your height. Stand straight, without shoes, for the most accurate reading.
- Select your gender. Each formula uses a different baseline and per-inch adjustment for men versus women.
- Pick your frame size. If you're not sure, a rough guide is wrist circumference relative to height β a smaller wrist relative to height typically means a smaller frame.
- Read the range. The big number shows a combined target range; the grid breaks out each individual formula plus the healthy-BMI weight range.
The Formulas Behind the Numbers
The Devine formula, published in 1974, was originally created to help clinicians calculate drug dosages. For men it's 50 kg plus 2.3 kg for every inch over 5 feet; for women it's 45.5 kg plus 2.3 kg per inch over 5 feet. The Robinson formula (1983) adjusted those constants slightly: 52 kg plus 1.9 kg per inch for men, 49 kg plus 1.7 kg per inch for women. The Miller formula (1983) uses yet another set of constants β 56.2 kg plus 1.41 kg per inch for men, 53.1 kg plus 1.36 kg per inch for women. The Hamwi formula, developed in 1964 for quick bedside estimates, uses 106 lb plus 6 lb per inch over 5 feet for men, and 100 lb plus 5 lb per inch over 5 feet for women. All four are well documented in clinical nutrition literature and referenced by resources like the National Library of Medicine. The healthy-BMI range comes straight from CDC guidance on adult BMI categories.
Why These Formulas Disagree by 10-15 Pounds
Here's the part most ideal-weight calculators don't tell you: these formulas were built decades apart, on different patient populations, for different clinical purposes, and they routinely land 10 to 15 pounds apart from each other for the exact same height and gender. Devine tends to run leaner. Miller tends to run heavier. Robinson and Hamwi usually fall somewhere in between. None of them account for muscle mass, bone density, or where on your body you carry weight β variables that matter enormously for how healthy and functional a given body weight actually is.
That spread isn't a flaw in the calculator β it's the honest truth about "ideal weight" as a concept. These are 1970s-era clinical shortcuts, not modern precision science. A 6-foot, heavily muscled man could weigh 220 lbs and be lean and athletic, or a sedentary 6-foot man could weigh 220 lbs and carry significant excess fat. The Devine formula gives both men the same "ideal weight" target, which obviously misses something important about their actual health.
There Is No Single "Right" Number
Because of that disagreement between formulas, the most useful way to read this tool is as a range, not a verdict. If your current weight falls somewhere between the lowest and highest formula result β or within the healthy-BMI range β you're almost certainly in a reasonable zone. If you're well outside all four numbers on the high or low end, that's worth a conversation with a doctor, not because a formula from 1974 said so, but because extreme deviation from a broad four-formula range is a more meaningful signal than any single equation.
It's also worth remembering that none of these formulas were designed with athletes, older adults, or people carrying significant muscle mass in mind. If that's you, a body composition measurement β body fat percentage, waist circumference, or lean body mass β tells you far more about your actual health than where you land on a 50-year-old chart.
Body Composition Matters More Than the Scale
Two people can share the exact same height, weight, and "ideal weight" formula result and be in completely different health situations, because the formulas only measure total body weight β they have no idea how much of that weight is muscle versus fat. A person with 15% body fat and a person with 35% body fat at the identical weight and height are not equally healthy, even though every formula on this page would score them the same.
That's why we built this as one tool in a set. Pairing your ideal weight range with an actual body fat percentage or lean body mass figure gives you the fuller picture that the scale alone can't provide.
Pair your ideal weight range with a lean body mass or body fat estimate for a more complete view. Arb Digital builds fast, high-converting websites and content β explore our free tools while you're here.
Lean Body Mass Calculator All Free ToolsWhere These Formulas Came From
It's worth understanding the backstory, because it explains a lot about why these numbers should be treated as rough guides rather than targets to chase. The Hamwi formula was created by Dr. George Hamwi in 1964 as a quick mental-math method for clinicians to estimate a patient's weight at the bedside β long before body composition scanning existed. The Devine formula followed a decade later, built specifically to standardize drug dosing calculations, particularly for medications where dosing by total body weight could be dangerously inaccurate in people carrying a lot of fat mass. Robinson and Miller each refined the constants slightly based on newer population data available in the early 1980s. None of the four were ever intended as fitness or aesthetic benchmarks β that's a use case they've simply been adapted for over time, well outside their original clinical purpose.
Knowing this history matters because it reframes what these numbers can and can't tell you. They were built to get a reasonably safe weight estimate for a general hospital population, not to define what a healthy or attractive body should weigh. Using them as a rough sanity check is reasonable. Using them as a strict target to hit is putting more weight on 50-year-old bedside math than it was ever designed to carry.
How to Use Your Result Alongside Other Health Markers
The most useful way to apply this calculator is as one data point among several, not the final word. Combine your ideal weight range with how your clothes fit, your energy levels, your strength and endurance in the gym, your resting heart rate, and if available, routine bloodwork like cholesterol and blood sugar markers from a doctor. A person who falls slightly outside the calculated range but has strong energy, good bloodwork, and solid strength numbers is very likely in better health than someone who falls neatly inside the range but is sedentary and metabolically unhealthy. The number on this page is a starting conversation, not a diagnosis.
Common Mistakes to Avoid
- Treating one formula as gospel. Always look at the full spread, not just the first number you see.
- Ignoring muscle mass. Athletes and lifters will often sit above these ranges while being perfectly healthy.
- Chasing an exact number. A range is more honest than a single target weight.
- Guessing frame size randomly. Use wrist circumference relative to height as a simple sanity check.
- Using it for children or teens. These formulas are built for adults; pediatric growth charts are a completely different tool.
- Ignoring other health markers. Bloodwork, energy levels, and fitness matter as much as, or more than, where you fall in this range.
Related Free Tools From Arb Digital
Check your BMI calculator results alongside this range, estimate your lean body mass, calculate your BMR, or work out your daily macros for a specific goal. You can also check your body fat percentage. Browse our full free online tools hub for more.
Frequently Asked Questions
An ideal weight calculator estimates a healthy weight range for your height and gender using several established clinical formulas, rather than one single "correct" number.
Each formula was developed decades apart on different patient groups for different clinical purposes, so they use different constants and routinely land 10-15 pounds apart from each other.
None is definitively "most accurate" for everyone β they're all rough clinical estimates. Looking at the full range across formulas is more informative than picking one.
Frame size adjusts the estimate by about 10% up or down to roughly account for bone structure, but it's an approximation, not a precise measurement.
Athletes and people with significant muscle mass will often weigh more than these formulas suggest while still being very healthy, so body composition tools are more useful for that group.
Not exactly β the healthy-BMI range is a broader, population-level guideline, while "ideal weight" formulas were designed for narrower clinical uses like medication dosing.
This tool provides general estimates for educational purposes only and is not medical advice. Individual needs vary β consult a doctor or registered dietitian before making health, nutrition, or fitness decisions.
