Ideal Body Weight Formula 2026 — Devine, Robinson, Miller, Hamwi

Four major ideal body weight (IBW) formulas exist 2026, all sex- and height-specific. DEVINE FORMULA (1974, most clinically-used): Men: 50 kg + 2.3 kg per inch over 5 feet. Women: 45.5 kg + 2.3 kg per inch over 5 feet. ROBINSON FORMULA (1983): Men: 52 kg + 1.9 kg per inch over 5 feet. Women: 49 kg + 1.7 kg per inch over 5 feet. MILLER FORMULA (1983): Men: 56.2 kg + 1.41 kg per inch over 5 feet. Women: 53.1 kg + 1.36 kg per inch over 5 feet. HAMWI FORMULA (1964, oldest): Men: 48 kg + 2.7 kg per inch over 5 feet. Women: 45.5 kg + 2.2 kg per inch over 5 feet. Devine + Hamwi are clinical (medication dosing). Robinson + Miller more conservative.

Honest answer 2026: NONE are accurate for individual assessment. All 4 formulas were developed for clinical drug dosing in 1960s-80s based on small population samples (US/UK adults, mostly Caucasian). They IGNORE: muscle mass (bodybuilders show "obese" by IBW), body composition (fat vs lean ratio), bone density (Pacific Islander/Polynesian populations), age (sarcopenia in elderly), ethnicity. For drug dosing: Devine formula remains FDA standard (still used in 2026 hospital pharmacy software). For YOUR ideal weight: BMI is also flawed but better. Body fat percentage via DEXA scan ($150-250) or InBody scan ($30-50 at gym) more useful. Actual best metric: how you feel + perform + look + bloodwork. Number on scale = least useful health metric.

BMI (Body Mass Index) is a single-number ratio: weight (kg) / height (m)². Categories per WHO: Underweight <18.5, Normal 18.5-24.9, Overweight 25-29.9, Obese 30+. BMI vs IBW formulas: BMI is universal (same for any height/sex within ratio). IBW formulas have separate male/female + height-specific calculations. BMI flaws: ignores body composition. A 200 lb 6 ft athlete with 8% body fat = BMI 27 (overweight) — clearly wrong assessment. A 130 lb 5'8" sedentary person with 35% body fat = BMI 19.8 (normal) — concerning despite "normal" BMI. Better metrics 2026: waist-to-height ratio (target <0.5), waist circumference (men <40", women <35"), body fat % (men 10-22% healthy, women 18-32%). Use BMI + IBW + waist as triangulation, NOT individual targets.

Practical IBW use cases 2026: (1) MEDICAL: Drug dosing (anesthesia, anticoagulants like warfarin) uses Devine IBW for patients with elevated BMI. Hospital protocols. (2) MILITARY: Service members held to specific weight standards by height (Army, Navy, Air Force, Marines). Each service has own table. (3) SPORTS: Wrestling, boxing, MMA weight class targets. Coaches use IBW as starting point + body composition adjustments. (4) GENERAL HEALTH: Use BMI + waist + body fat instead. (5) NUTRITION: Calorie/protein per IBW (e.g., 1.6-2.2g protein per kg IBW for athletes). NOT useful for: sedentary individuals tracking fat loss progress (BMI better), pregnant women (special weight gain charts), kids (CDC growth charts), athletes (body comp matters more), elderly 65+ (different optimal ranges due to sarcopenia).

5'10" man (10 inches over 5 feet, height 178 cm) ideal body weight by formula: DEVINE: 50 + (2.3 × 10) = 73 kg = 161 lbs. ROBINSON: 52 + (1.9 × 10) = 71 kg = 156 lbs. MILLER: 56.2 + (1.41 × 10) = 70.3 kg = 155 lbs. HAMWI: 48 + (2.7 × 10) = 75 kg = 165 lbs. Range 155-165 lbs across all 4 formulas. BMI normal range for 5'10" (1.78m): 130-173 lbs (BMI 18.5-24.9). The BMI normal range is WIDER than IBW formulas because BMI isn't height-specific in nuance. Practical: a 5'10" man at 170 lbs with 12% body fat is healthier than at 155 lbs with 25% body fat. Composition + waist > absolute weight. For 5'10" man: waist <39 inches matters more than scale.

5'4" woman (4 inches over 5 feet, height 163 cm) ideal body weight by formula: DEVINE: 45.5 + (2.3 × 4) = 54.7 kg = 121 lbs. ROBINSON: 49 + (1.7 × 4) = 55.8 kg = 123 lbs. MILLER: 53.1 + (1.36 × 4) = 58.5 kg = 129 lbs. HAMWI: 45.5 + (2.2 × 4) = 54.3 kg = 120 lbs. Range 120-129 lbs across formulas. BMI normal range for 5'4" (1.63m): 108-145 lbs. Practical guidance for 5'4" woman: waist <35 inches better target than absolute weight. Body fat 18-28% optimal range. A 5'4" woman at 135 lbs with 22% body fat (athletic) is healthier than at 118 lbs with 32% body fat ("skinny fat"). Composition + waist circumference + bloodwork (lipids, glucose, inflammation markers) — these matter for actual health.

Historical context for 4 IBW formulas 2026: HAMWI (1964): Original formula by Dr. George Hamwi for diabetes management. Used insulin dosing calculations. Population: US adults 1960s era. DEVINE (1974): Modified by Dr. Ben Devine for tobramycin antibiotic dosing. Slight reduction from Hamwi. Became hospital standard worldwide. Still preferred 2026 for drug dosing. ROBINSON (1983): Updated for newer population data (BMI standards from 1980s). Slightly more conservative than Devine. MILLER (1983): Developed using larger Asian + Pacific population sample. Gives slightly lower weight than Devine. Recommended for non-Caucasian patients in some clinical contexts. All 4 share common structure: base weight + offset per inch above 5 feet. Choice depends: Drug dosing → Devine. General reference → Devine or Robinson average. Asian populations → Miller. Modern alternative: avoid IBW formulas entirely; use BMI + body composition + waist circumference.

Practical 2026 guidance: YOUR ideal weight = where you feel best + perform best + bloodwork is optimal. Multi-metric approach: (1) BMI 18.5-25 range (with caveats for muscular build). (2) Waist-to-height ratio <0.5 (target 0.45). (3) Body fat % healthy ranges: men 10-22%, women 18-32% (varies by age). (4) Bloodwork: lipid panel, A1C, inflammation markers (CRP) — these reveal metabolic health regardless of weight. (5) Performance: can you do daily activities without fatigue? Athletic capacity? (6) Quality of life: energy, sleep, mood. Set ranges, not specific numbers. "I feel best at 165-175 lbs" is more sustainable than "I must hit 168 lbs". Annual physical with bloodwork + waist measurement provides better trajectory data than daily scale weight. SCALE WEIGHT is the LEAST useful health metric — it conflates muscle, fat, water, glycogen, food in transit.