Ideal Weight Calculator
Find your ideal weight range using 5 medical formulas with frame size adjustment.
Last reviewed: May 2026| Formula | lbs | kg |
|---|---|---|
| Devine (1974) | - | - |
| Robinson (1983) | - | - |
| Miller (1983) | - | - |
| Hamwi (1964) | - | - |
| BMI-based (BMI 22) | - | - |
Quick Answer
Ideal body weight estimates a healthy weight range from your height and sex using clinical formulas like Devine, Robinson, Miller, and Hamwi. For example, the Devine formula gives about 160 lbs for a 5'10" man. These are population averages, not targets for any individual. Enter your height and sex above to compare results across five formulas.
This calculator computes "ideal body weight" (IBW) using five historical clinical formulas — Devine (1974), Robinson (1983), Miller (1983), Hamwi (1964), and a BMI 22 target. These formulas were developed for narrow medical purposes: drug dosing, ventilator settings, and dialysis calculations. They were never validated as predictors of personal health or longevity. The sections below explain where each formula came from, why they disagree, and what modern medicine actually uses to assess body composition and health.
What This Calculator Does
The Five Formulas in One Place
Enter your height and biological sex; the calculator outputs five different "ideal" weights side by side. Each formula uses a base value for a 5-foot adult plus a fixed increment per inch above 60 inches. Devine adds 2.3 kg per inch for men (1.9 kg for women) on top of a 50 kg / 45.5 kg base. Robinson uses 1.9 kg / 1.7 kg per inch on a 52 kg / 49 kg base. Miller adds 1.41 kg / 1.36 kg per inch on 56.2 kg / 53.1 kg. Hamwi uses 2.7 kg / 2.2 kg per inch on a 48 kg / 45.5 kg base. The BMI 22 target multiplies 22 by your height in meters squared, producing a single weight centered in the WHO "normal" BMI range. An optional frame-size multiplier (small −10%, large +10%) approximates skeletal-frame variation that the raw formulas ignore.
Why Compare All Five Instead of Picking One
None of these formulas was designed as a personal weight target, and none agrees with the others to within more than about ten pounds at a given height. By showing all five side by side, the calculator makes the underlying uncertainty visible: there is no single answer to "what should I weigh" because the formulas were not built to answer that question. They were built to standardize drug dosing across heterogeneous patient populations in the 1960s and 1970s, when individualized DEXA-scan body composition was not technically feasible.
What This Calculator Is Not
This is not a diet calculator, a weight-loss goal tool, or a medical assessment. It is a reference for the historical clinical formulas still cited in pharmacology, anesthesiology, and critical-care textbooks. If you are looking for a personal health benchmark, the BMI calculator, body-fat estimator, or — far better — a conversation with a physician and a DEXA scan will tell you substantially more than these IBW formulas can.
How to Use It
Step-by-Step
First, select your biological sex (the formulas use sex-specific coefficients, primarily because the original 1960s–1980s study cohorts were stratified by sex and the resulting fits differ). Second, switch between imperial and metric units depending on which is more comfortable; the underlying math is identical because the calculator converts to centimeters internally. Third, enter your height. Optionally, select small, medium, or large frame to apply the standard ±10% skeletal-frame adjustment used in the Metropolitan Life and Hamwi clinical traditions.
Reading the Output
The headline "Ideal Weight Range" shows the minimum and maximum across all five formulas — typically a 10–15 pound spread. The breakdown table lists each formula individually in both pounds and kilograms. The BMI-based panel shows the BMI 22 midpoint plus the full 18.5–24.9 "normal" BMI band for your height. Treat the range as a reference window, not a target. If your actual weight falls outside the range, that fact alone tells you essentially nothing about your health — it just means your body composition does not match the assumptions baked into 50-year-old clinical formulas.
Sharing and Saving
The share URL encodes your inputs as query parameters, so a bookmarked link will reproduce the same output. This is useful for clinicians who want to send a patient the same reference page, or for personal records. The print view strips the navigation and ad slots, leaving a clean printout suitable for attaching to a medical chart or care plan.
Worked Example: 5'8" Male, then 5'4" Female
Example 1 — 5'8" (173 cm) Male, Medium Frame
- Height
- 5'8" = 68 inches = 1.7272 m
- Extra inches over 60
- 8
- Devine (1974)
- 50 + 2.3 × 8 = 68.4 kg ≈ 151 lb
- Robinson (1983)
- 52 + 1.9 × 8 = 67.2 kg ≈ 148 lb
- Miller (1983)
- 56.2 + 1.41 × 8 = 67.5 kg ≈ 149 lb
- Hamwi (1964)
- 48 + 2.7 × 8 = 69.6 kg ≈ 153 lb
- BMI 22 target
- 22 × 1.7272² = 65.6 kg ≈ 145 lb
- Range across formulas
- 145–153 lb (about 8 pounds spread)
The spread of roughly 8 pounds at this height is typical. Devine and Hamwi sit at the top end, BMI 22 at the bottom. None of these numbers tells you whether a 5'8" male weighing, say, 175 lb is healthy or unhealthy — that depends entirely on body composition, fitness, and metabolic markers, none of which any IBW formula measures.
Example 2 — 5'4" (163 cm) Female, Medium Frame
- Height
- 5'4" = 64 inches = 1.6256 m
- Extra inches over 60
- 4
- Devine (1974)
- 45.5 + 2.3 × 4 = 54.7 kg ≈ 121 lb
- Robinson (1983)
- 49 + 1.7 × 4 = 55.8 kg ≈ 123 lb
- Miller (1983)
- 53.1 + 1.36 × 4 = 58.5 kg ≈ 129 lb
- Hamwi (1964)
- 45.5 + 2.2 × 4 = 54.3 kg ≈ 120 lb
- BMI 22 target
- 22 × 1.6256² = 58.1 kg ≈ 128 lb
- Range across formulas
- 120–129 lb (about 9 pounds spread)
For shorter women, the BMI 22 and Miller values tend to sit at the high end of the range while Devine and Hamwi sit at the low end. This inversion (compared to the male example) reflects different per-inch increments in each formula and is one reason no single formula can claim primacy.
Why Multiple Formulas Exist
Devine (1974) — Drug Dosing, Not Health
The Devine formula was published in 1974 by hospital pharmacist B. J. Devine in Drug Intelligence and Clinical Pharmacy with the explicit purpose of standardizing aminoglycoside antibiotic doses (gentamicin, tobramycin) in adult patients. Drugs that distribute primarily into lean tissue need to be dosed against lean body weight rather than actual weight, because dosing an obese patient against total body weight would deliver a toxic concentration to the lean-tissue compartment where the drug actually acts. Devine derived his coefficients (50 kg base + 2.3 kg/inch for men) from a small, retrospective hospital sample — the goal was utility, not population representativeness. Forty years later, Devine IBW is still the input variable for vancomycin nomograms, ventilator tidal volume calculations under the ARDSNet 6 mL/kg lung-protective protocol, and many neuromuscular blocker dosing protocols.
Hamwi (1964) — Insurance Actuarial Tables with Racial Bias
The Hamwi formula was published in 1964 by endocrinologist George Hamwi based on Metropolitan Life Insurance Company actuarial tables tracking mortality among life-insurance policyholders. The underlying data came from policyholders who, in 1960, were overwhelmingly white, middle-class, and male; the tables were stratified by frame size but inherited the demographic bias of the underwriting population. Multiple subsequent analyses have flagged that "ideal weights" derived from 1959 and 1960 Met Life tables systematically underestimated healthy weight ranges for Black Americans, Pacific Islanders, and other populations excluded or underrepresented in the original cohort. Despite these limitations, the Hamwi formula remained widely used in clinical nutrition and dietetics through the 1990s and is still taught in registered-dietitian training programs as a quick mental-math reference.
Robinson (1983) and Miller (1983) — Updates, Not Revolutions
Robinson and colleagues published a revision of Devine in 1983 in the American Journal of Hospital Pharmacy, using a larger and more demographically varied sample. The Robinson coefficients shifted slightly (52 kg base + 1.9 kg/inch for men) but preserved Devine's fundamental clinical-tool framing. The Miller formula, published the same year by Miller et al., used yet another statistical fit and produced slightly different per-inch increments. Both formulas live alongside Devine in modern pharmacology references without one displacing the others — clinicians often run all three and average them when high-stakes dosing accuracy matters.
BMI 22 — Epidemiological, Not Clinical
The "BMI 22 target" comes from a different intellectual tradition entirely: it sits near the nadir of the all-cause mortality U-curve in many large population studies (Framingham, NHANES, EPIC) of predominantly Western populations. Multiplying 22 by height-in-meters-squared produces a single weight at the bottom of the mortality curve. The mortality curve flattens significantly across BMI 20–27, however, meaning the practical advantage of BMI 22 over BMI 25 is small and often disappears entirely once you control for fitness, smoking, and socioeconomic confounders.
Limitations and Disclaimers
What IBW Does Not Account For
The historical IBW formulas treat every adult of a given height and sex as if they share a single body composition. They do not adjust for muscle mass — which is why athletes virtually always exceed IBW; for bone density — which varies substantially with age, race, and physical activity history; for essential fat — which is biologically required and differs by sex (women carry roughly 12% essential fat including breast and reproductive-organ tissue, men 3%); for age — sarcopenia after age 60 progressively reduces lean mass, meaning an elderly person at their 30-year-old IBW may actually be malnourished; for ethnicity — Asian populations show elevated cardiometabolic risk at lower BMI, while Pacific Islander populations show the opposite pattern; for pregnancy — IBW formulas are simply undefined for pregnant patients; or for medical conditions like edema, ascites, or amputation that change body weight without changing nutritional status.
What Modern Medicine Uses Instead
For drug dosing in non-average patients, hospitals calculate Lean Body Weight (LBW) using formulas like Janmahasatian (2005), which incorporate actual weight alongside height and sex, or Adjusted Body Weight (ABW = IBW + 0.4 × (actual − IBW)) for obese patients on lipophilic drugs that distribute partially into adipose tissue. The James equation and the Hume equation are also widely used. For nutritional and health assessment, registered dietitians increasingly bypass IBW entirely in favor of body composition measurements (DEXA, bioelectrical impedance), functional metrics (grip strength, walking speed), and biochemical markers (albumin, prealbumin, lipid panel).
When IBW Is Genuinely Useful
IBW remains a legitimate clinical input in three contexts: drug dosing (where consistency across patients is more important than perfect accuracy for any single patient), mechanical ventilation tidal volume calculations (where the ARDSNet 6 mL/kg IBW protocol has been validated in randomized trials), and dialysis adequacy modeling (where target weight is partly derived from IBW-like calculations). Outside these clinical contexts, IBW has very limited utility as a guide for individual behavior.
Modern Body-Composition Metrics
DEXA Scan — The Gold Standard
Dual-energy X-ray absorptiometry (DEXA) scans use two low-dose X-ray beams of different energies to separately measure fat mass, lean (non-bone) mass, and bone mineral content for each body region. The total radiation dose is roughly equivalent to one day of natural background radiation. A DEXA scan reports total body fat percentage, regional fat distribution (android vs. gynoid, a key cardiometabolic risk indicator), appendicular lean mass index (important for sarcopenia screening), and bone density (the same machines used for osteoporosis assessment). DEXA scans run $50–$250 cash-pay in most U.S. metros and provide far more clinically actionable information than any IBW formula.
Bioelectrical Impedance Analysis (BIA)
BIA scales send a small alternating current through the body and measure the resistance encountered. Because fat-free mass conducts electricity better than fat (due to higher water content), the resistance value can be inverted into a body-fat-percentage estimate. Consumer BIA scales are convenient and cost $30–$200, but they are sensitive to hydration status, recent exercise, meal timing, and skin temperature — repeatable error of ±3–5 percentage points is typical. Multi-frequency clinical BIA devices (InBody, Tanita MC-series) deliver substantially tighter precision but cost $500–$5,000.
Hydrostatic Weighing and Air Displacement
Hydrostatic underwater weighing measures body density by comparing land weight to submerged weight, then converts density to body-fat percentage using the Siri or Brozek equations. It was the research gold standard for decades before DEXA. Air displacement plethysmography (the BodPod) achieves comparable precision using air rather than water, which is more comfortable for participants. Both methods are accurate but cost $50–$150 per session and are not widely available outside research universities and elite athletic training facilities.
Skinfold Calipers
Skinfold caliper measurements at standard anatomical sites (chest, abdomen, thigh, triceps, suprailiac) feed into the Jackson-Pollock or Durnin-Womersley equations to estimate body-fat percentage. Done well by a trained technician, skinfold testing produces ±3% accuracy at very low cost. Done poorly by an untrained user, the error can easily exceed ±5% — site location and pinch technique matter enormously.
Waist-to-Hip Ratio and Waist-to-Height Ratio
Waist-to-hip ratio (WHR) divides waist circumference by hip circumference. The WHO defines abdominal obesity as WHR above 0.90 for men or 0.85 for women. Visceral abdominal fat is far more cardiometabolically toxic than subcutaneous fat on hips and thighs, so WHR captures risk information that BMI misses entirely. Waist-to-height ratio (WHtR) is simpler and arguably more useful: target below 0.5 for adults of any height. Multiple meta-analyses since 2010 have found WHtR outperforms BMI for predicting cardiovascular and metabolic disease.
Body Roundness Index (BRI, 2013)
Thomas et al. published the Body Roundness Index in 2013 (Obesity) as a geometric model treating the human torso as an ellipse defined by height and waist circumference. BRI ranges from approximately 1 (very narrow ellipse) to 16 (highly rounded ellipse). Several subsequent validation studies have shown BRI predicts visceral adiposity and cardiometabolic risk more accurately than BMI in mixed-sex adult populations. BRI is not yet in widespread clinical use but is gaining traction in research and in some preventive-medicine practices.
Health Disclaimer
What This Calculator Provides
This calculator provides historical clinical-reference values from five published formulas. The output is informational only. It is not a diagnosis. It is not a personal weight goal. It is not a substitute for any kind of clinical assessment, nutritional counseling, or medical advice. If you are using this page to set a personal weight target, please stop and consider whether body composition, fitness, and metabolic health might be more relevant signals than a single number derived from 1960s and 1970s clinical formulas.
Body Weight Is a Poor Proxy for Health
The strongest predictors of long-term health outcomes — all-cause mortality, cardiovascular events, cancer incidence — are cardiorespiratory fitness (VO₂ max), strength (grip strength, leg-press 1RM), and metabolic markers (fasting insulin, HbA1c, lipid panel, blood pressure). Weight enters those predictive equations only weakly and often disappears entirely once fitness is controlled for. The 2018 American Heart Association position paper "Obesity and Cardiovascular Disease" explicitly notes that fitness is a stronger predictor of cardiovascular mortality than body weight or BMI across virtually all adult populations.
Disordered Eating Risk
Using IBW or BMI 22 as a personal target carries genuine risk of triggering or exacerbating disordered eating, especially in adolescents, young women, athletes, and individuals with a prior history of eating disorders. The National Eating Disorders Association (NEDA) explicitly recommends against using numerical weight targets without clinical supervision. If reading these numbers triggers anxiety about your weight, please consider contacting NEDA's helpline (800-931-2237) or a qualified mental-health professional rather than acting on the formulas.
Talk to a Professional
Before making any weight-management decision — losing weight, gaining weight, restricting calories, starting a new exercise program, taking GLP-1 medications, considering bariatric surgery — talk to a physician, an endocrinologist, or a registered dietitian. They can integrate your medical history, family history, current medications, body composition, and laboratory values into a recommendation tailored to your individual context. A free online calculator cannot do any of that, and pretending otherwise is irresponsible.
| Height | Devine | Robinson | Miller | Hamwi | BMI 22 | Spread |
|---|---|---|---|---|---|---|
| 5'4" (163 cm) | 129 lb | 131 lb | 136 lb | 129 lb | 128 lb | 8 lb |
| 5'6" (168 cm) | 140 lb | 139 lb | 143 lb | 141 lb | 136 lb | 7 lb |
| 5'8" (173 cm) | 151 lb | 148 lb | 149 lb | 153 lb | 145 lb | 8 lb |
| 5'10" (178 cm) | 161 lb | 156 lb | 156 lb | 165 lb | 153 lb | 12 lb |
| 6'0" (183 cm) | 172 lb | 164 lb | 163 lb | 176 lb | 162 lb | 13 lb |
| 6'2" (188 cm) | 183 lb | 173 lb | 170 lb | 188 lb | 171 lb | 18 lb |