Ideal Weight Calculator 2026 — Four Doctors Disagree on Your Perfect Weight

Ideal Weight Calculator 2026 — Four Doctors Disagree on Your Perfect Weight

Type your height into the ideal weight calculator on CalcMint Pro and you will receive four different numbers — one from the Hamwi formula, one from the Devine formula, one from the Robinson formula, and one from the Miller formula. All four were developed by medical professionals. All four are based on height. And all four give meaningfully different answers for the same person. A 5'10" man gets ideal weight estimates ranging from 166 pounds to 172 pounds depending on which formula is used. A 5'6" woman gets estimates ranging from 130 pounds to 139 pounds. The disagreement is not a flaw in the calculator — it is the honest truth about what medical science actually knows about ideal body weight. This guide explains where each formula came from, what it was designed for, why they disagree, and — most importantly — what ideal weight actually means for your specific body, goals, and health.

Where the Four Formulas Came From

The Hamwi Formula (1964)

Dr G.J. Hamwi developed this formula for clinical use in calculating drug dosages — specifically insulin requirements for diabetic patients. It was never intended as a general health benchmark.

For men: 106 pounds for the first 5 feet of height, plus 6 pounds for every inch above 5 feet For women: 100 pounds for the first 5 feet of height, plus 5 pounds for every inch above 5 feet

Example — 5'10" man: 106 + (10 × 6) = 166 pounds Example — 5'6" woman: 100 + (6 × 5) = 130 pounds

The Devine Formula (1974)

Dr B.J. Devine created this formula originally for calculating drug dosages in clinical pharmacology — particularly for medications where lean body mass determines dosing. Like Hamwi it was a clinical tool before it became a general health reference.

For men: 50kg + 2.3kg for every inch above 5 feet For women: 45.5kg + 2.3kg for every inch above 5 feet

Example — 5'10" man: 50 + (10 × 2.3) = 73kg = 161 pounds Example — 5'6" woman: 45.5 + (6 × 2.3) = 59.3kg = 131 pounds

The Robinson Formula (1983)

Dr J.D. Robinson developed this formula as a modification of the Devine formula — recognising that Devine's estimates seemed slightly low for taller individuals.

For men: 52kg + 1.9kg for every inch above 5 feet For women: 49kg + 1.7kg for every inch above 5 feet

Example — 5'10" man: 52 + (10 × 1.9) = 71kg = 157 pounds Example — 5'6" woman: 49 + (6 × 1.7) = 59.2kg = 130 pounds

The Miller Formula (1983)

Dr D.R. Miller developed yet another modification — producing the highest ideal weight estimates of the four formulas for most heights.

For men: 56.2kg + 1.41kg for every inch above 5 feet For women: 53.1kg + 1.36kg for every inch above 5 feet

Example — 5'10" man: 56.2 + (10 × 1.41) = 70.3kg = 155 pounds Example — 5'6" woman: 53.1 + (6 × 1.36) = 61.3kg = 135 pounds

The Critical Problem With All Four Formulas

Every one of these formulas shares the same fundamental limitation — they use height as the only input variable. No formula accounts for:

Body frame size. A large-framed 5'10" man with wide shoulders, thick wrists, and dense bone structure naturally carries more weight than a small-framed man of the same height — even at identical body fat percentages. The classic test for frame size is wrist circumference relative to height — a 5'10" man with a wrist circumference above 7.5 inches has a large frame and should add 10% to standard formula results.

Muscle mass. All four formulas were developed before body composition measurement was widely available. They assume a population-average body composition — approximately 15% to 20% body fat for men and 22% to 28% for women. A man with significantly above-average muscle mass will correctly weigh more than these formulas suggest — not because he is overweight but because muscle is denser and heavier than fat.

Age. Ideal body weight for a 25-year-old and a 65-year-old are physiologically different. Older adults who carry slightly more weight in the BMI overweight range actually show lower mortality in several large studies — the so-called obesity paradox discussed in the BMI calculator guide. The formulas take no account of age.

Ethnicity. People of Asian descent have higher health risk at lower body weights than these formulas — developed primarily on Western populations — would suggest. The formulas likely overestimate ideal weight for Asian individuals by 5% to 10%.

Sex-specific body composition differences. The formulas account for sex through different constants but do not capture the full range of sex-based body composition variation — including the dramatically different essential fat requirements for women versus men discussed in the body fat calculator guide.

Ideal Weight Reference Tables — All Four Formulas

For Men

For Women

The average of all four formulas generally provides the most reasonable estimate for most adults of average frame size and body composition — which is why the ideal weight calculator shows all four alongside the range they define.

How to Use the CalcMint Pro Ideal Weight Calculator

Step 1 — Enter your height. Height is the only measurement these formulas require. Enter in feet and inches or centimetres depending on your preference.

Step 2 — Select your sex. Men and women use different formula constants — selecting correctly is essential for an accurate result.

Step 3 — View all four formula results. The calculator displays Hamwi, Devine, Robinson, and Miller estimates alongside each other — giving you the full range rather than a single potentially misleading number.

Step 4 — Interpret your result in context. Use the average of all four as your starting benchmark. Adjust upward by 5% to 10% if you have a large frame or significant muscle mass. Use the body fat calculator to check your current body fat percentage — because the ideal weight target is most meaningful when paired with a body composition goal.

Step 5 — Cross-reference with BMI range. A weight in the BMI 18.5 to 24.9 range for your height represents the normal weight category — which for most people broadly overlaps with the formula estimates. The BMI calculator shows the full normal weight range for your height as a complementary reference.

The BMI-Based Ideal Weight Range — A Practical Alternative

Rather than using a single formula result the healthy weight range defined by a BMI between 18.5 and 24.9 gives a range of weights that captures the diversity of healthy body weights at each height more realistically than any single formula number.

The healthy weight calculator shows this range directly — but here is the reference table for common heights.

Notice how wide these ranges are — a 5'10" person can healthily weigh anywhere from 129 to 174 pounds — a 45-pound range. The single formula estimates (157 to 167 pounds for that height) fall in the middle of this range which makes sense — they represent the statistical average not the full healthy range.

Who Uses the Ideal Weight Calculator and Why

People starting a weight loss or fitness journey use it to establish a preliminary target before working with a coach or nutritionist. The formula average gives a concrete starting goal — but as noted above it should be adjusted based on frame size and ultimately replaced by a body composition goal once body fat percentage data is available.

Healthcare providers use the Devine formula specifically for calculating drug dosages in clinical pharmacology — including antimicrobials, chemotherapy agents, and certain anaesthetics where dosing based on ideal rather than actual body weight reduces toxicity risk in obese patients.

Fitness coaches use it as a rough initial benchmark before body composition testing. Most experienced coaches quickly move clients from scale-weight targets to body fat percentage targets once the limitations of weight-only goals become apparent.

People who have never had a formal fitness goal and want a starting reference point before calculating their calorie deficit using the calorie calculator or their full energy needs using the TDEE calculator.

When the Ideal Weight Formula Gets It Wrong

Understanding the scenarios where formula results are genuinely misleading helps you interpret your number correctly.

Highly muscular individuals. A male competitive powerlifter at 5'10" weighing 210 pounds with 10% body fat — 189 pounds of lean mass — would be told his ideal weight is 163 pounds by the formula average. Achieving that weight would require eliminating 47 pounds of lean tissue — a physiological and performance catastrophe. His optimal weight from a health standpoint is his current 210 pounds. The formula is simply wrong for this individual.

Very petite individuals. A woman at 5'0" with a genuinely small frame — small wrists, narrow shoulders, fine bone structure — may be completely healthy at 95 to 100 pounds despite all four formulas suggesting 100 to 117 pounds as ideal. Frame size adjustment is legitimate and important.

Older adults. Research including the Nurses Health Study found that women over 60 had lowest mortality at BMI values slightly above the 18.5 to 24.9 normal range — suggesting that for older adults maintaining slightly higher body weight than the ideal formulas suggest may be protective rather than harmful. Some researchers suggest older adults may benefit from a target BMI of 22 to 27 rather than the standard 18.5 to 24.9.

Pregnant women. Ideal weight formulas are entirely inapplicable during pregnancy — appropriate weight gain during pregnancy is a separate clinical calculation based on pre-pregnancy BMI and gestational age.

People recovering from eating disorders. Ideal weight targets should only be used in the context of eating disorder recovery under direct clinical supervision — the psychological impact of numerical weight targets in this context requires careful professional management.

Real-World Example: Three People at the Same Height With Very Different Ideal Weights

All three are women at 5'6" — formula average ideal weight: 128 pounds.

Person A — Maya, 28, recreational runner: Current weight: 135 pounds Current body fat: 22% (fitness category) Lean mass: 105.3 pounds Assessment: 7 pounds above formula average but in the fitness body fat range. Her actual ideal weight for health and performance is closer to 130 to 138 pounds — the formula underestimates her optimal weight due to above-average lean mass from running.

Person B — Rebecca, 44, sedentary office worker: Current weight: 128 pounds — exactly at formula average Current body fat: 33% (overweight category) Lean mass: 85.8 pounds Assessment: At formula ideal weight but in the overweight body fat range — low muscle mass and high fat mass despite a normal scale weight. This is textbook normal-weight obesity — the formula completely misses the body composition issue. Her actual health goal should be building lean mass, not maintaining scale weight.

Person C — Lisa, 35, powerlifter: Current weight: 158 pounds — 30 pounds above formula average Current body fat: 18% (athletic category) Lean mass: 129.6 pounds Assessment: Significantly above formula ideal weight but in the athletic body fat range with exceptional lean mass. The formula's 128-pound suggestion would require Lisa to lose 30 pounds — almost certainly lean mass — causing significant performance and health decline. Her optimal weight is her current 158 pounds.

Same height. Same formula result. Three completely different optimal weights. This is why the formula is a starting reference — not a prescription.

The Body Composition Approach — A Better Target Than a Scale Number

The most useful evolution from ideal weight thinking is replacing the scale-weight target with a body composition target — a specific combination of weight and body fat percentage that reflects the physique and health markers you actually want.

Instead of: "I want to reach 140 pounds" Use: "I want to reach 140 pounds at 22% body fat — giving me 109 pounds of lean mass"

The second target is specific, measurable, and physiologically meaningful. It tells you not just where to stop on the scale but what your body should be made of when you get there — and whether the weight you lose is coming from fat or from muscle.

Calculate your current body fat percentage using the body fat calculator. Find your current lean mass (body weight × (1 − body fat%)). Set a target body fat percentage from the category tables above. Calculate your target weight as lean mass ÷ (1 − target body fat%). This gives you a physiologically grounded target weight that accounts for your actual body composition rather than a formula estimate based on height alone.

Set your calorie target for reaching that goal using the calorie calculator, establish your protein requirements using the protein intake calculator, and split your macros using the macro calculator. That is the complete evidence-based roadmap from where you are to where you want to be.

Pro Tip — The Formula Range Matters More Than Any Single Number

The most practically useful output of the ideal weight calculator is not any single formula result but the range defined by all four formulas together. For a 5'10" man the range is 155 to 166 pounds. Any weight within this range — when accompanied by a healthy body fat percentage — represents a legitimate and healthy target.

Choosing a specific number within that range based on your frame size, muscle mass, and performance goals is the intelligent application of formula data. Using the formula result as an absolute target to be achieved at any cost — including sacrificing muscle mass — is the misapplication that causes harm.

Use the ideal weight calculator as your orientation tool. Use the body fat calculator as your progress tracking tool. Use the BMI calculator as your broad health context tool. None of these numbers alone tells the complete story — but together they give you a genuinely comprehensive picture of your body composition and health status that no single metric can provide.

Published by James Carter | CalcMint Pro | Updated May 2026