Ideal Weight Calculator
5 Medical Formulas · Metric & Imperial
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in
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Enter your height to see your ideal weight across 5 medical formulas.
Average Ideal Weight
0
lbs (average of 4 formulas)
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The 5 Ideal Weight Formulas Explained
Ideal body weight (IBW) formulas were originally developed for clinical use — primarily for calculating medication dosages, anaesthesia doses, and ventilator settings. They were never intended as definitive "target weights" for the general population. Each formula uses only height and sex, making them simple but limited tools that ignore muscle mass, body frame, and age.
| Formula | Year | Men (base + per inch) | Women (base + per inch) | Primary Use |
|---|---|---|---|---|
| Devine | 1974 | 50 kg + 2.3 kg/in | 45.5 kg + 2.3 kg/in | Drug dosing, most widely used |
| Robinson | 1983 | 52 kg + 1.9 kg/in | 49 kg + 1.7 kg/in | Modified Devine, broader use |
| Miller | 1983 | 56.2 kg + 1.41 kg/in | 53.1 kg + 1.36 kg/in | Conservative estimate |
| Hamwi | 1964 | 48 kg + 2.7 kg/in | 45.5 kg + 2.2 kg/in | Dietetics and nutrition |
| BMI Range | — | 18.5 – 24.9 × height (m)² | General population health | |
All formulas calculate weight for heights above 5 feet (152 cm) in imperial units. For heights below 5 feet, the calculations become less reliable. The BMI-based range (18.5-24.9) is currently the most evidence-backed approach for general population weight assessment, though it shares the same limitation of not accounting for body composition.
Why Formulas Differ
Each formula was derived from a different research population and clinical context. Devine was based on a drug dosing study from the 1970s. Robinson and Miller updated the Devine formula with larger datasets. Hamwi was developed for dietetics. None were designed as population health targets — the differences reflect the imprecision inherent in reducing a complex individual to two variables: height and sex.
Frame Size Adjustment
Some practitioners adjust ideal weight by 10% for frame size. Small frame: subtract 10%. Medium frame: use as-is. Large frame: add 10%. Frame size can be estimated by measuring wrist circumference. For women: small (<5.5 in), medium (5.5-5.75 in), large (>5.75 in). For men at 5'11": small (<6.5 in), medium (6.5-7.5 in), large (>7.5 in). This adjustment accounts somewhat for bone density differences.
Healthy Weight vs Ideal Weight
Ideal weight (from formulas) and healthy weight (BMI 18.5-24.9) are not identical. The formula-derived IBW typically falls in the lower-to-middle portion of the BMI healthy range. A person can be healthy at any weight within the BMI 18.5-24.9 range. The IBW formulas were designed for clinical utility, not aesthetic or personal goals — treat them as one data point, not a target.
Athletes and Muscular Individuals
All ideal weight formulas will underestimate appropriate weight for highly muscular individuals. A 5'10" competitive athlete with 8% body fat may weigh 200+ lbs, far above the 165-166 lb IBW for that height. For athletic populations, body fat percentage (target 6-17% men, 14-24% women for fitness) is a more appropriate metric than formula-derived ideal weight. Use IBW as a general reference only.
Ideal weight formulas are clinical estimation tools, not personal weight targets. Healthy weight varies by individual. Consult a healthcare professional or registered dietitian for personalized guidance.
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Frequently Asked Questions
Which ideal weight formula is most accurate?+
No single formula is universally "most accurate" — each was developed for different clinical contexts. The Devine formula (1974) is the most widely used in clinical settings, particularly for drug dosing, anaesthesia, and ventilator tidal volume calculations. The Hamwi formula is popular in dietetics. BMI-based ranges (18.5-24.9) are the most evidence-backed approach for general population health assessment. Using an average of multiple formulas gives a more balanced estimate. For personal weight goals, your doctor or registered dietitian can provide guidance specific to your health history and body composition.
How much should I weigh for my height?+
Weight ranges by height (men): 5'6" = 136-152 lbs, 5'8" = 149-166 lbs, 5'10" = 163-181 lbs, 6'0" = 177-197 lbs. Women tend to run 10-15 lbs lighter at the same heights. These ranges represent the span between the lowest formula estimate and the top of the BMI healthy range. Body weight is highly individual — two people at the same height can be equally healthy at significantly different weights depending on muscle mass, bone density, and body frame. Enter your exact height in the calculator above for formula-specific estimates.
Does ideal weight account for muscle mass or frame size?+
Standard ideal weight formulas do not account for muscle mass or bone density. They use only height and sex. A bodybuilder and a sedentary person of the same height would get identical "ideal weight" results despite having vastly different body compositions. Frame size adjustments of plus or minus 10% are sometimes applied to account for large or small skeletal frames. For muscular individuals, body fat percentage is a far more meaningful measurement than ideal weight. Athletes at 200 lbs may be leaner and healthier than a sedentary person at their "ideal" 165 lbs.
What is the Devine formula for ideal body weight?+
The Devine formula, published by B.J. Devine in 1974, calculates: Men: 50 kg + 2.3 kg for each inch over 5 feet. Women: 45.5 kg + 2.3 kg for each inch over 5 feet. Example for a 5'10" male: 50 + (2.3 × 10) = 50 + 23 = 73 kg (161 lbs). For a 5'6" female: 45.5 + (2.3 × 6) = 45.5 + 13.8 = 59.3 kg (131 lbs). It was originally developed for drug dosing calculations, not as a weight loss target, which is often misunderstood.
How is ideal weight different from healthy weight range?+
Ideal weight (single number from a formula) and healthy weight range (BMI 18.5-24.9 span) serve different purposes. The IBW formulas produce a single point estimate designed for clinical calculations. The BMI healthy range defines a band — for a 5'10" male, that is 129-173 lbs, a 44-pound range. IBW formulas typically land in the lower-to-middle portion of this range. Neither approach is a target you must hit. Being anywhere within the BMI healthy range is associated with similar health outcomes. Pursuing a specific "ideal weight" number is less clinically meaningful than maintaining body fat percentage and metabolic health within healthy ranges.
Does ideal weight change with age?+
Standard IBW formulas do not include age as a variable. However, research suggests that slightly higher BMI (25-27) may be protective for adults over 65, as it provides reserves against illness, muscle wasting (sarcopenia), and recovery from surgery or illness. The American Geriatrics Society recognizes that the "ideal" weight for a 70-year-old may be higher than the formula suggests. For older adults, maintaining muscle mass through resistance training matters more than achieving a specific scale weight. The formulas remain most applicable and most accurate for adults aged 20-60.
How much should a 5-foot-10 man weigh?+
For a 5'10" (178 cm) male: Devine formula gives 73 kg (161 lbs), Robinson gives 71.5 kg (158 lbs), Miller gives 76.3 kg (168 lbs), Hamwi gives 75 kg (165 lbs). The average of the four formulas is approximately 164 lbs (74.5 kg). The BMI healthy range for this height is 129-173 lbs (58-78 kg). Most medical sources would consider 155-175 lbs a reasonable weight range for a 5'10" man of average build, though lean muscular individuals may healthily exceed this. Use the calculator above for your exact measurements.
How much should a 5-foot-6 woman weigh?+
For a 5'6" (168 cm) female: Devine formula gives 59.1 kg (130 lbs), Robinson gives 59.5 kg (131 lbs), Miller gives 61.3 kg (135 lbs), Hamwi gives 59 kg (130 lbs). Average across formulas: approximately 131-132 lbs (59.5 kg). BMI healthy range for this height is 115-154 lbs (52-70 kg). Most clinicians would consider 120-150 lbs a reasonable healthy range for a 5'6" woman, with variation for muscle mass, frame size, and age. Women with higher muscle mass from athletic training may be healthy at 155-165 lbs at this height.
Should I aim for my ideal weight?+
Ideal weight formulas are clinical reference points, not personal targets. Research on weight and health shows that metabolic health markers (blood glucose, blood pressure, cholesterol, triglycerides) matter more than scale weight alone. A person can have a "normal" BMI or ideal weight and have poor metabolic health, and vice versa. Instead of targeting a specific number, most evidence supports focusing on: regular physical activity (150+ minutes of moderate exercise per week), strength training to build and preserve muscle, a balanced whole-food diet, adequate sleep, and stress management. If weight loss is a health goal, a registered dietitian can help set realistic, evidence-based targets.
Why do ideal weight formulas give different results?+
The formulas differ because they were each derived from different research populations in different decades. Devine (1974) based his formula on a clinical observation study. Robinson et al. (1983) reanalyzed data from life insurance tables and the NHANES survey, arriving at different constants. Miller et al. (1983) used yet another dataset. Hamwi (1964) developed a rule-of-thumb for dietitians. No formula is "correct" in an objective sense — they reflect different snapshots of population data and different methodological choices. The spread between formulas (typically 5-15 lbs at most heights) illustrates the inherent imprecision of reducing individual body weight to a single height-based estimate.