Ideal Weight Calculator

What weight should you actually aim for? Compare the four classic clinical formulas — Devine, Robinson, Miller and Hamwi — side by side, plus the healthy BMI range for your height. No single magic number: a sensible target band.

What Is “Ideal Weight”?

Ideal body weight (IBW) is a reference number originally created for clinical work — drug dosing, anaesthesia, and nutrition planning — not for setting personal fitness goals. Four formulas dominate, all built on the same structure: a base weight for someone five feet tall, plus a fixed amount for every inch above that. They differ only in their two constants, yet they return noticeably different answers for the same person.

That disagreement is the point. There is no single agreed “ideal” weight for a given height. The honest answer is a band, and the spread between the formulas shows you how wide it is. Treat the average as a reference and the healthy BMI range as your outer guardrails.

The Four Formulas

Worked example: a man who is 5 ft 10 in (70 inches, 10 inches over five feet). Devine gives 50 + 2.3 × 10 = 73.0 kg. Robinson gives 52 + 1.9 × 10 = 71.0 kg. Miller gives 56.2 + 1.41 × 10 = 70.3 kg. Hamwi gives 48 + 2.7 × 10 = 75.0 kg. The four answers span 70.3–75.0 kg, averaging 72.3 kg — and the healthy BMI range at that height (1.78 m) is wider still, 58.6–78.9 kg.

Why the Formulas Disagree

• Different origins: Devine was devised for drug dosing in 1974; Robinson and Miller (1983) were fitted to life-insurance mortality data; Hamwi (1964) came from diabetes nutrition planning. None was designed as a personal beauty standard.
• Different slopes: Hamwi adds 2.7 kg per inch, Miller only 1.41 kg. The taller you are, the wider the gap between them.
• Missing variables: no formula includes age, frame size, muscle mass, or ethnicity. A muscular person and a sedentary person of the same height get the same answer, which cannot be right for both.
• Below five feet: the increment runs in reverse, and none of the authors validated the formulas for very short or very tall people. Treat those results as rough guidance only.

The World Health Organization frames healthy weight as a BMI band rather than a point, which is the more defensible view. The National Heart, Lung, and Blood Institute similarly emphasises ranges and overall risk factors over single numbers.

How to Use Your Result

Start with the four-formula average as a reference point, then adjust for reality. If you carry a lot of muscle, the top of the healthy BMI range — or even slightly above it — may be right for you; check your body fat percentage to decide. If you are older or sedentary, the lower half of the range may suit you better. Your BMI tells you where you sit today relative to the band.

Once you pick a target, the practical tools take over: your BMR gives your resting burn, the calorie calculator turns it into a daily target, and the TDEE calculator adds cutting and bulking options. Don’t forget hydration while you change your routine — see your daily water intake.

Tips for Setting a Realistic Target

• Think in bands, not points. A 5 kg target zone is realistic; a single kilogram is noise.
• Revisit quarterly. Muscle gain, ageing, and lifestyle changes all move the right answer over time.
• Don’t chase the lowest number. The bottom of the BMI range is not healthier than the middle — risk is lowest across the middle of the band.
• Pair weight with composition. Losing 5 kg of fat while gaining 2 kg of muscle looks like “only” 3 kg on the scale but is a big health win.
• Talk to a professional for extremes. If your current weight is far outside the band in either direction, a doctor or dietitian should guide the plan.

Ideal Weight Lookup by Height

Instead of running each formula by hand, use this lookup table. It shows the Devine result — the most widely quoted clinical formula — for men and women, next to the healthy BMI range for the same height, so you can see the point estimate and the sensible band side by side:

Notice how wide the BMI band is compared with the single Devine number — at 5 ft 10 in, the band spans 20 kg. That width is honest: it reflects real differences in frame, muscle, and build. If your current weight sits inside the band, chasing the exact Devine figure is rarely worth the effort.

A Brief History of Ideal Weight

The idea of an ideal weight did not start in fitness culture. It started in life insurance. In the 1940s and 1950s, the Metropolitan Life Insurance Company published “desirable weight” tables built from mortality data on millions of policyholders: the weights at which people lived longest. Those tables, based on small, medium, and large frames, became the public’s first picture of a correct weight.

The formulas came later, and each had a clinical job, not a cosmetic one. Hamwi (1964) was developed for diabetes nutrition planning. Devine (1974) was devised to estimate drug doses and creatinine clearance in hospitals. Robinson and Miller (1983) were fitted to the same insurance mortality data. None of their authors claimed to have found the weight every person of a given height should aim for — yet that is exactly how the numbers came to be used, once calculators put them a click away from everyone.

Two People, Same Height, Different Targets

Take two men, both 5 ft 10 in. The Devine formula gives both of them 73.0 kg. The first is a sedentary office worker who never trains; at 73 kg with 30% body fat, he carries 21.9 kg of fat and 51.1 kg of lean tissue, and his metabolic health is mediocre despite hitting the “ideal” number exactly. The second is a rugby player at 95 kg with 15% body fat: 14.3 kg of fat and 80.7 kg of lean tissue. He is 22 kg over his ideal weight and far healthier by every measure that matters — blood pressure, blood sugar, strength, and fitness.

The lesson is not that the formulas are useless; it is that they answer a narrow question (what does the average person of this height weigh at a reference point?) while you are asking a broader one (what weight is healthy for me?). Answer the broader question with a body fat percentage check and your BMI band, and use the formula result only as a starting reference.

Frame Size: The Missing Adjustment

One variable the classic formulas ignore is frame size — the size of your skeleton. Two people of the same height can differ by several kilograms of bone and structural tissue. A rough way to estimate frame is wrist circumference: measure your wrist just below the hand bones. As a rule of thumb, a man under 175 cm tall with a wrist under 16.5 cm has a small frame, 16.5 to 19 cm is medium, and over 19 cm is large; for women under 160 cm, the bands are roughly under 14 cm, 14 to 16.5 cm, and over 16.5 cm.

Some older charts adjusted ideal weight by plus or minus 10% for large and small frames. That adjustment is crude and was never validated the way the formulas were, but it points in the right direction: a large-framed person should treat the top of the BMI band as their zone, and a small-framed person the lower half. If your frame is notably large or small, let that shift your target by a few kilograms rather than chasing a number built for an average skeleton.

How to Calculate Ideal Weight by Hand

Every formula on this page follows the same recipe: start from a base weight at five feet tall, then add a fixed amount for each inch above five feet. Once you know the two constants for a formula, you can work it out on paper in under a minute. Follow the steps below, then check your answer against the calculator above.

1. Measure your height barefoot and convert it to feet and inches.
2. Subtract 60 inches (five feet) from your height in inches — this is the number of inches over five feet.
3. Multiply those inches by the formula’s per-inch amount (2.3 kg for Devine, for example).
4. Add the result to the formula’s base weight (50 kg for men, 45.5 kg for women under Devine).
5. Repeat for the other three formulas and average the four answers for your reference weight.

Worked example: a woman who is 5 ft 6 in tall is 6 inches over five feet. Devine gives 45.5 + 2.3 × 6 = 59.3 kg. Robinson gives 49 + 1.7 × 6 = 59.2 kg. Miller gives 53.1 + 1.36 × 6 = 61.3 kg. Hamwi gives 45.5 + 2.2 × 6 = 58.7 kg. The average is 59.6 kg — and the four answers span only 2.6 kg, because at this height the formulas agree closely. The disagreement grows with height, as the next section shows.

All Four Formulas at One Height

At 5 ft 10 in, the formulas have had ten inches to diverge, and the spread is already visible. Hamwi, with its steep slope, gives the highest answer for both sexes, while Miller gives the lowest for men. The table below shows all four answers side by side for the same height, so the size of the disagreement is plain to see.

For men the spread is 4.7 kg, from 70.3 to 75.0 kg; for women it is only 2.5 kg, from 66.0 to 68.5 kg, because the women’s per-inch amounts differ less. Either way, the honest conclusion is the same: the “ideal” weight is a zone several kilograms wide, not a point. Anyone quoting a single ideal weight to the decimal place is overstating what these formulas can know.

The Devine Result Across Heights

Devine is the most quoted of the four formulas, so it is worth seeing how its answer climbs with height. The table below shows the Devine result for men and women at five heights, stepping four inches at a time. Each four-inch step adds 9.2 kg for both sexes, because the per-inch amount is the same 2.3 kg — the lines run parallel, separated always by the 4.5 kg difference in the base weights.

The mechanical regularity is itself the warning: real healthy weights do not climb in perfect 9.2 kg steps, because real bodies differ in frame, muscle, and build. The formula is a ruler, not a measurement of you. Use it as a starting reference, then adjust with the checks in the sections below.

Ideal Weight Versus the Healthy BMI Range

The healthy BMI range (18.5 to 24.9) gives a band for each height, and that band is far wider than any single formula answer. The table below puts the Devine number inside its band for three heights, so you can see how much room the band allows around the point estimate.

At every height, the Devine number sits in the upper half of the band, not the middle — a reminder that these formulas were fitted to particular reference populations rather than to the centre of healthy weight. If your current weight sits inside the band, chasing the exact formula number is rarely worth the effort. The band is the honest answer; the formula number is a landmark inside it. Check where you stand with the BMI calculator, and check what your weight is made of with the body fat calculator, before deciding that a number needs to move.

When the Formulas Should Not Be Used

The four formulas share the same blind spots, because they share the same structure: height and sex in, weight out, with nothing else considered. In the situations below, the numbers they return are misleading enough to ignore.

• Children and teenagers: growing bodies follow age-based growth charts, not adult formulas — a child’s healthy weight changes every year.
• Pregnancy: weight gain is expected and healthy, and no pre-pregnancy formula applies — discuss targets with your provider and use the due date calculator for timing instead.
• Athletes and lifters: muscle weighs more than fat, so muscular people overshoot every formula while being perfectly healthy.
• Older adults: muscle loss with age means the formulas can overstate the right weight for a frail person, or understate it for a fit one.
• Amputees and people with limb differences: the formulas assume a standard body structure that does not apply.
• Very short or very tall people: the formulas were never validated far from average height, and their disagreement grows at the extremes.

Children and Teens Need Growth Charts

A child’s healthy weight is judged against BMI-for-age percentile charts, which compare the child with others of the same age and sex. A 10-year-old and a 15-year-old can share the same BMI number and sit in completely different categories, because growth changes the reference constantly. Never apply the adult formulas — or the adult BMI bands — to anyone under 18.

Pregnancy Has Its Own Guidance

During pregnancy, recommended weight gain depends on pre-pregnancy BMI, and the ranges used by providers allow for the baby, placenta, extra blood volume, and fluid. The formulas on this page know nothing of any of that, and applying them during pregnancy would set a target that ignores the entire purpose of the weight being gained. Pre-pregnancy weight is the reference point; pregnancy weight is managed with a provider.

Setting a Target Weight Step by Step

A target weight is a decision, not a calculation, and it deserves a short process rather than a single click. Work through the steps below in order, and the number you land on will be one you can actually live with.

1. Run the calculator and note the four-formula average and the healthy BMI band for your height.
2. Check your BMI to see where your current weight sits relative to the band.
3. Check your body fat percentage — if you train, this decides whether the band or the formula average is the better guide.
4. Pick a target zone 3 to 5 kg wide inside the band, not a single kilogram.
5. Set your daily intake with the calorie calculator, using your BMR as the floor.
6. Review the target after three months, or after every 5 kg of change, whichever comes first.

• If you are far above the band: aim first for 5 to 10% of your current weight — that first stage already brings large health benefits.
• If you are inside the band: consider whether any change is needed at all; fitness and strength may be better goals than weight.
• If you are below the band: aim to gain steadily with food and resistance training, and involve a professional if appetite or digestion is a problem.

Ideal Weight and Body Composition Together

The two worked cases from the history section show why composition must sit beside any formula number. Both men are 5 ft 10 in, so both get the same Devine answer of 73.0 kg — and their health pictures could hardly be more different.

The office worker carries more fat despite weighing less; the player carries less fat despite weighing far more. Any system that calls the first man ideal and the second overweight has measured the wrong thing. Use the formula average as a reference, the BMI band as guardrails, and body fat percentage as the tie-breaker — and when they disagree, trust composition and your doctor over the formula.

• Formula average: the clinical reference point, useful for dosing and screening.
• BMI band: the population guardrails, wide enough for real variation.
• Body fat percentage: the personal tie-breaker, showing what the weight is made of.
• Waist size: the abdominal-fat check that catches risk the others miss.

Signs Your Target Weight Is Unrealistic

A target that cannot be held is worse than no target, because each failure makes the next attempt harder. Watch for these warnings and revise the target upward when several appear.

• Reaching it would require eating below your BMR for months on end.
• You have held a stable, healthy weight for years several kilograms above it, with good blood markers and fitness.
• It sits below a weight you held comfortably in young adulthood without dieting.
• It ignores a large frame, a muscular build, or a medical condition that your doctor considers relevant.
• Thinking about it dominates meals, social plans, and mood.

Targets should serve health, not punish the body that carries you. If the number on this page and the life you actually live disagree, adjust the number — with your doctor’s input when the gap is large.

Frequently Asked Questions

Which formula is the most accurate?

None is “accurate” for individuals — they are population references. Devine is the most widely quoted in clinical settings, but the average of all four is a more honest reference than any single one.

Why does Hamwi give the highest number?

Because it adds the most per inch (2.7 kg for men). For taller people, that steep slope pushes the result well above the other three formulas.

Does ideal weight account for frame size?

No. Some calculators add a ±10% frame adjustment (small/medium/large), but the classic four formulas ignore frame entirely. If you have a notably large or small frame, adjust the band mentally by a few kilograms.

Is the healthy BMI range better than ideal weight?

For most people, yes. A range respects individual variation — muscle, frame, age — where a single formula number pretends it doesn’t exist.

Can I use this calculator if I am under 5 feet tall?

You can, but treat the results cautiously: the formulas were never validated below five feet, and the numbers are extrapolated. The BMI range is the safer guide in that case.

My ideal weight is lower than I expected. Should I aim for it?

Not necessarily. Treat the healthy BMI band as your zone and the formula result as a reference inside it. If the formula number sits well below a weight where you feel strong and healthy, there is no prize for reaching it — and if you are far outside the band in either direction, a doctor or dietitian should guide the plan rather than a calculator.

Do these formulas work for very tall people?

Only roughly. The formulas were built from average-height populations, and the per-inch increments extrapolate badly beyond about 6 ft 2 in, where the formulas increasingly disagree. For very tall or very short people, the BMI band is the safer guide, combined with body fat percentage and waist measurements.

Is the average of four formulas better than one?

Yes, as a reference. Averaging cancels out part of each formula’s bias, since their errors run in different directions at different heights. The average is still a population reference, not a personal prescription — but it is more honest than any single formula quoted alone.

My weight is above my ideal but I feel fine. Is that a problem?

Not necessarily. Feeling fine is a weak test on its own — blood pressure, blood sugar, and cholesterol can be abnormal without symptoms — so get those checked. If the markers are good, you train regularly, and your body fat percentage sits in the fitness band, a number above the formula average may simply reflect muscle and frame.

Do the formulas change with age?

No, and that is one of their limits. They return the same answer at 25 and at 75 for the same height, while muscle mass, bone density, and healthy weight all shift with age. Older adults should read the result together with strength, mobility, and body composition rather than treating it as a fixed goal.

Should I include shoes and clothing in my height and weight?

No. Measure height barefoot and weight in light clothing, consistently. Shoes add 2 to 4 cm and clothing adds a kilogram or more, and both errors push the comparison in misleading directions. Consistency matters more than perfection: same scale, same conditions, every time.

Disclaimer: Ideal weight formulas are clinical references, not personal health targets. They ignore muscle mass, frame size, age, and ethnicity. Consult a healthcare professional for individual advice.