Ideal Weight Calculator
How to find your ideal weight
Three quick steps from your height to a target weight backed by four clinical formulas.
Pick your gender and unit system. Gender changes the base weight in every formula, and you can work in US, metric or stones — the form converts as you switch.
Enter your height, then your current weight (optional) so the tool can show the gap to your target. You can also pick a body frame to nudge the result up or down.
See your ideal weight averaged across four formulas, the healthy weight range for your height, the difference from your current weight, and a per-formula breakdown — then save a PDF.
Ideal Weight Calculator — A Target Backed by Four Formulas
Ideal body weight is a height- and sex-based estimate of a sensible target weight. The idea began with the Metropolitan Life insurance tables of the 1940s, which linked height and frame to longevity, and was later distilled into simple equations that clinicians, pharmacists and dietitians still use every day for drug dosing, ventilator settings and nutrition planning. This calculator runs four of the most established formulas — Devine, Hamwi, Robinson and Miller — reports each one, and averages them so you get a realistic target band rather than a single rigid figure. It works in US, metric and UK units, entirely in your browser.
The four ideal weight formulas explained
Every formula shares the same shape: a base weight at five feet of height, plus a fixed increment for each inch above that. The Devine formula (1974) — 50 kg for men, 45.5 kg for women, plus 2.3 kg per inch — is the most widely cited in medicine. The Hamwi formula (1964) is the oldest bedside method and gives men the steepest increment. The Robinson and Miller formulas (both 1983) refined Devine using insurance data, producing slightly lower targets with gentler per-inch increases. Because each was built on a different population, no one of them is "correct" — averaging them is the sensible approach, which is exactly what this tool highlights.
Ideal weight versus a healthy weight range
An ideal weight formula gives a single convenient number, but health is better described by a range. Alongside the formulas, this calculator shows your healthy weight range — the span of weights that keeps your BMI between 18.5 and 24.9 at your height. The formula figure usually lands near the middle of that band. Seeing both side by side stops you fixating on one number: the range tells you where the safe zone is, and the formula gives you a memorable mid-point to aim for. A spread of several pounds on either side is completely normal and healthy.
Body frame and why it matters
The single biggest factor the formulas leave out is skeletal frame. Two people of identical height can have noticeably different healthy weights simply because one has broader bones. A practical gauge is wrist circumference or elbow breadth: narrow joints suggest a small frame, broad joints a large one. As a rule of thumb, a small frame shifts a realistic target down by around ten percent and a large frame up by the same amount. That is why this tool offers an optional frame adjustment — it moves the target within a sensible band rather than pretending one number fits every build.
Weight management and realistic goals
Knowing your ideal weight is only useful if it leads to a realistic plan. If your current weight sits outside the healthy range, the calculator shows how far the nearest edge is, which keeps expectations grounded. Sustainable change — roughly half a kilogram to a kilogram a week — almost always outperforms aggressive crash diets, which tend to cost muscle and rebound. Pairing a gradual calorie adjustment with resistance training protects lean tissue, so the weight you lose is fat rather than muscle. The target is a direction, not a deadline.
Healthy lifestyle planning beyond the number
An ideal weight figure is a starting point, not a verdict on your health. Body composition, fitness, sleep, blood pressure and family history all shape wellbeing far more precisely than any single target weight. A muscular, active person can sit above their formula weight and be in excellent condition, while someone at their "ideal" number can still be unfit. Use this result to orient yourself, then build habits — regular movement, balanced meals, good sleep and stress management — that you can keep for life. Everything here is computed locally; your height and weight are never uploaded or stored.
Why use this ideal weight calculator?
Four trusted formulas, a healthy range and a clear target difference — all at once.
Devine, Hamwi, Robinson and Miller side by side, plus their average — so you see a target range, not one arbitrary number.
See the full band of weights that keeps your BMI in the healthy 18.5–24.9 zone for your height, shown on a clear visual scale.
Enter your weight and instantly see how far you are from the target and the nearest edge of the healthy range.
An optional frame adjustment shifts your target up or down by about ten percent, so the result fits your build, not an average one.
Switch between US (ft-in/lbs), metric (cm/kg) and UK (stones & pounds) in one tap, with values carried across automatically.
Download a clean, branded report with your ideal weight, healthy range and formula comparison — easy to keep or share.
The four ideal weight formulas compared
Each uses a base weight at 5 ft of height plus a per-inch increment. Here is how they differ.
| Formula | Men (base + per inch) | Women (base + per inch) | Year |
|---|---|---|---|
| Devine | 50.0 kg + 2.3 kg | 45.5 kg + 2.3 kg | 1974 |
| Hamwi | 48.0 kg + 2.7 kg | 45.5 kg + 2.2 kg | 1964 |
| Robinson | 52.0 kg + 1.9 kg | 49.0 kg + 1.7 kg | 1983 |
| Miller | 56.2 kg + 1.41 kg | 53.1 kg + 1.36 kg | 1983 |
Why the results differ
Hamwi gives men the steepest climb per inch, so it tends to read highest for tall men. Miller has the most generous base but the smallest increment, favouring shorter people. Devine sits in the middle and is the clinical default. Because each was fitted to a different population, averaging them — as this tool does — smooths out their individual quirks into a sensible target.
Ideal weight vs healthy range
The formulas give one tidy number, but a healthy weight is really a band. This calculator pairs the formula average with the BMI-based healthy range (18.5–24.9) for your height, so you can see both the mid-point target and the wider safe zone around it. Aiming for the range is more forgiving and more realistic than chasing a single figure.
Body frame and weight management
Frame size and lifestyle shift what a realistic target looks like for you.
| Body frame | Wrist (men) | Wrist (women) | Target adjustment |
|---|---|---|---|
| Small | Under 16.5 cm | Under 14 cm | About 10% lower |
| Medium | 16.5–19 cm | 14–16 cm | Formula target |
| Large | Over 19 cm | Over 16 cm | About 10% higher |
How to estimate your frame
Wrap a tape around your wrist just below the bony bump. Narrow joints point to a small frame and a lower target; broad joints to a large frame and a higher one. Frame matters because bone and connective tissue add real, healthy weight that the formulas — built only on height — cannot see.
Setting a healthy weight goal
Treat your ideal weight as the centre of a band, not a finish line. Aim for gradual change of about 0.5–1 kg per week, pair a modest calorie adjustment with resistance training to protect muscle, and judge progress over months. Sustainable habits keep the weight off far better than rapid diets.
Related health calculators
An ideal weight is one piece of the picture — combine it with these for the full view.
Frequently asked questions
Short, practical answers to the questions people ask most about ideal body weight.
Ideal body weight (IBW) is a height- and sex-based estimate of a healthy target weight, originally created for medical dosing. This tool uses four established formulas — Devine, Hamwi, Robinson and Miller. Each takes a base weight at 5 feet of height and adds a set amount per inch above that, with different coefficients. We show all four plus their average, so you get a target range rather than a single rigid number.
No single formula is universally correct. The Devine formula (1974) is the most widely used in clinical practice and a good default. Robinson and Miller are refinements based on insurance data, and Hamwi gives the highest values for men. Because they were built from Western population samples and ignore muscle and frame, clinicians often average them — which is why this calculator reports the mean alongside each formula.
Frame size — the width of your skeleton — shifts a realistic target by roughly ten percent in each direction. People with a small frame sit toward the lower end of the healthy range, and those with a large frame toward the upper end. You can gauge frame size from wrist circumference or elbow breadth. Treat the formula result as the centre of a band rather than an exact figure, and use the optional frame setting to adjust it.
An ideal weight formula gives a single target figure for your height and sex. A healthy weight range is the band of weights that keeps your BMI between 18.5 and 24.9 at your height. The range is broader and more forgiving, while the formula gives a convenient mid-point. This calculator shows both so you can aim for a realistic span rather than one precise number. For the BMI side of the picture, see our BMI calculator.
Not reliably. The formulas ignore muscle mass, so a muscular athlete can sit well above their formula weight while being lean and healthy — a body fat measurement is more useful there. They are also validated for adults aged 18 and over, not children or teenagers, whose targets follow age- and sex-specific growth charts. Use the result as general guidance alongside professional advice.
Treat the figure as the centre of a sensible band — about five pounds either side is normal — rather than a fixed target. If your current weight sits outside the healthy range, the calculator shows how far the nearest edge is so you can plan realistic, gradual change. Sustainable habits beat rapid swings, and a dietitian or doctor can tailor a target to your frame, muscle and health history.