Ideal Weight Calculator
Find your ideal body weight (IBW) using four proven medical formulas — Devine, Robinson, Miller, and Hamwi — alongside your BMI healthy weight range.
Ideal weight formulas are based on height only — weight is optional below.
Medically Reviewed
Dr. Sarah Mitchell, RD — Registered Dietitian Nutritionist
Formulas, references, and recommendations cross-checked against published clinical research from NIH, CDC, WHO, and the Academy of Nutrition and Dietetics. Read our full Editorial Policy.
What Is Ideal Body Weight (IBW)?
Ideal body weight (IBW) is a concept used in medicine and nutrition to estimate a healthy target weight based on height and sex. Unlike BMI, which uses both height and weight, IBW formulas predict a target weight from height alone — useful for drug dosing, ventilator settings in ICUs, and nutritional planning.
The four major ideal weight formulas — Devine, Robinson, Miller, and Hamwi — were developed between 1964 and 1983, before modern understanding of body composition. They're based on average frame sizes and don't account for muscle mass, bone density, ethnicity, or age. Treat them as guides, not strict targets.
📏
Height-based
not weight-based
Unlike BMI, ideal weight formulas only need your height — simple to use and remember.
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Clinical origin
built for medicine
Originally created for drug dosing and ventilator settings — now used broadly for weight guidance.
⚖️
A guide, not a rule
body composition matters more
A muscular athlete and a sedentary person can have the same IBW yet very different health profiles.
The Four Ideal Weight Formulas Compared
All four formulas share the same structure: a base weight at 5 feet (60 inches) plus an increment for each additional inch. The differences lie in the base weight and per-inch values.
Devine (1974)
Male: IBW = 50 + 2.3 × (height_in − 60)
Female: IBW = 45.5 + 2.3 × (height_in − 60)
height_in = height in inches
The most widely cited formula. Originally developed by Dr. B.J. Devine for calculating drug doses based on body weight. Still standard in pharmacology and ICU dosing today.
Robinson (1983)
Male: IBW = 52 + 1.9 × (height_in − 60)
Female: IBW = 49 + 1.7 × (height_in − 60)
height_in = height in inches
A revision of Devine with a smaller per-inch increment. Produces slightly lower values for taller adults. Often used in clinical nutrition and parenteral feeding calculations.
Miller (1983)
Male: IBW = 56.2 + 1.41 × (height_in − 60)
Female: IBW = 53.1 + 1.36 × (height_in − 60)
height_in = height in inches
Published the same year as Robinson but uses the highest base weight and smallest per-inch increment — so results stay close to Robinson for average heights but diverge at extremes.
Hamwi (1964)
Male: IBW = 48 + 2.7 × (height_in − 60)
Female: IBW = 45.5 + 2.2 × (height_in − 60)
height_in = height in inches
The oldest formula, by Dr. G.J. Hamwi. Uses the largest per-inch increment, producing the highest ideal weights for taller individuals — often considered more realistic for athletic builds.
How Accurate Are Ideal Weight Formulas?
Honestly — only moderately. Ideal weight formulas were developed for narrow clinical use cases, and they have well-documented limitations when applied as personal targets.
1. They predate body composition science
All four formulas were published before DEXA scans, bioelectrical impedance, and hydrostatic weighing became standard. They cannot distinguish between fat mass and lean mass — a critical limitation.
2. They assume an average frame size
The original studies sampled adults of average bone structure. Small-, medium-, and large-frame individuals can legitimately weigh ±10% from a formula's prediction without any health consequence.
3. They were built on US/European populations
Hamwi (1964), Devine (1974), Robinson (1983), and Miller (1983) were all derived from data on predominantly Caucasian American hospital patients. Application to global populations is approximate at best.
4. They don't account for age
Body composition shifts with age — typically toward lower lean mass and higher body fat. A formula calibrated to young adults is less accurate for adults over 50, and least accurate over 70.
5. The four formulas disagree
For a 5'10" (178 cm) man, the four formulas range from 70 kg to 79 kg — a 9 kg spread. The spread itself proves that no single 'ideal' number exists.
Bottom line: The average of the four formulas, used alongside the BMI healthy weight range (18.5–24.9), gives a realistic target zone — not a single magic number. For deeper assessment, pair with body fat percentage, waist-to-height ratio, and basal metabolic rate.
Ideal Weight for Athletes & Muscular Individuals
If you train seriously, lift weights, or play a power sport, you will almost certainly weigh well above your calculated ideal body weight — and that's perfectly healthy. The reason is simple: muscle is denser than fat. One liter of skeletal muscle weighs about 1.06 kg; one liter of body fat weighs about 0.90 kg. A bodybuilder and a sedentary office worker of the same height can hold the same IBW result yet differ by 15–25 kg of lean mass.
✅ What athletes should track instead
- • Body fat percentage via DEXA scan or US Navy method (use our Body Fat Calculator)
- • Lean body mass (LBM) — track increases over time
- • Performance metrics — strength PRs, run times, recovery
- • Resting heart rate and HRV
- • Waist-to-hip ratio — better cardiometabolic indicator
❌ What athletes should NOT do
- • Force weight down to a formula's IBW number
- • Cut calories below BMR to "hit a target weight"
- • Trust BMI alone — it labels most NFL athletes "obese"
- • Set a weight goal during peak training season
- • Compare your scale weight to non-athletic peers
Typical bodybuilders, powerlifters, and rugby players commonly carry 15–30 kg of muscle above their formula IBW. For high-performance athletes, the right target is a healthy body fat percentage — typically 6–13% for men, 14–20% for women — not a scale number. Use the Calorie Calculator to plan your maintenance and lean-bulk targets.
Ideal Weight by Age
Body composition shifts naturally with age — and the four classic ideal weight formulas don't account for it. Here's what changes across life stages.
Adolescents (13–17)
IBW formulas are not validated for teens. Growth is uneven (height first, weight catches up) and body composition shifts rapidly with puberty. Use pediatric BMI percentiles from the WHO or CDC growth charts instead — they account for age and sex.
Young adults (18–30)
Formulas work best here. Lean mass peaks in the mid-20s, metabolism is at lifetime highs, and body composition is most stable. Average ideal weight formulas align reasonably well with healthy BMI ranges for most young adults of average frame.
Adults (31–50)
Slow metabolic slowdown and gradual muscle loss (sarcopenia) begin. Resistance training and adequate protein become critical. IBW targets remain useful but should be paired with body fat tracking — gaining fat while losing muscle can keep scale weight stable.
Adults (51–70)
Sarcopenia accelerates without resistance training. Bone density may decrease. Research published in JAMA and the Journal of the American Geriatrics Society suggests a slightly higher BMI (24–28) may be protective for adults over 65, contradicting strict adherence to IBW.
Older adults (71+)
Maintaining muscle mass becomes the primary health goal — not hitting a scale weight. Underweight in older adults is independently associated with higher mortality. Discuss any intentional weight change with a physician or registered dietitian.
Ideal Weight Across Ethnicities
All four ideal weight formulas were derived from predominantly North American and European populations. Decades of research published by the WHO, NIH, and major peer-reviewed journals show that body composition and cardiometabolic risk thresholds differ meaningfully across ethnic backgrounds.
Asian populations
The WHO recognizes lower BMI cutoffs for Asian populations: overweight at BMI ≥ 23 and obese at BMI ≥ 27.5, versus 25 and 30 for general populations. This reflects evidence of higher visceral fat and diabetes risk at lower BMIs in South Asian, East Asian, and Southeast Asian groups.
African and African-diaspora populations
Research from the NIH-funded Jackson Heart Study and others shows higher lean mass at the same BMI in many African and African-American adults, meaning standard BMI thresholds may overestimate body fat. Waist circumference and waist-to-height ratio are particularly informative complements.
European populations
The classic IBW formulas were calibrated to this group, so the four formulas work most accurately here — but still don't capture frame size or athletic body composition.
Latino / Hispanic populations
Studies show heterogeneous body composition across Latino subgroups, often with higher body fat at the same BMI compared to non-Hispanic Caucasian populations. Waist circumference cutoffs may need adjustment in clinical use.
Pacific Islander populations
Often have higher lean mass and bone density. Standard BMI thresholds tend to overestimate obesity prevalence; body composition assessment via DEXA or skinfold is recommended for individuals from these groups.
These are population averages drawn from peer-reviewed research — individual variation is significant. Discuss appropriate weight targets with a registered dietitian or physician familiar with your background and medical history.
Ideal Weight vs Other Health Metrics
Ideal weight is just one of several ways to assess a healthy body. The best clinical picture uses multiple metrics together.
| Metric | Inputs | Accuracy | Best Use Case | Limitations |
|---|---|---|---|---|
| Ideal Weight (IBW) | Height, sex | Low–moderate | Drug dosing, quick reference | Ignores muscle mass, frame size, ethnicity, age |
| BMI | Height, weight | Moderate | Population screening, broad guide | Doesn't distinguish fat from muscle |
| Body Fat % | Skinfold / Navy / DEXA | High | Body composition tracking | Method-dependent; requires measurement |
| Waist-to-Height | Waist, height | High | Cardiometabolic risk | Doesn't capture overall composition |
| Lean Body Mass | Weight, body fat % | High | Athlete tracking, muscle goals | Requires accurate body fat measurement |
Best practice: use ideal weight as a starting reference, BMI as your range, and body fat percentage for body-composition truth. Add waist-to-height ratio if your cardiometabolic risk profile matters.
Health Disclaimer: Ideal weight formulas were originally designed for clinical drug dosing, not personal weight management. Results vary significantly with frame size, muscle mass, age, and ethnicity. This calculator is for general informational purposes only and is not a substitute for personalized advice from a registered dietitian (RD/RDN), physician, or other qualified healthcare professional. Discuss any intentional weight change with a licensed clinician.
Frequently Asked Questions
Authors & Medical Review
Written By
SamCalculator Editorial Team
Health and nutrition writers covering evidence-based weight management, body composition, and clinical references. Read more on our About page.
Medically Reviewed By
Dr. Sarah Mitchell, RD
Board-certified Registered Dietitian Nutritionist (RDN) specializing in weight management, body composition, and clinical nutrition. Reviews all formulas, statistics, and recommendations on this page.
Last medically reviewed: May 11, 2026 · Last updated: May 11, 2026
Scientific References
- National Institutes of Health (NIH) — Body Weight Planner & calorie/weight modeling
- Centers for Disease Control and Prevention (CDC) — Adult BMI guidelines
- World Health Organization (WHO) — Obesity and overweight fact sheet (incl. Asian BMI cutoffs)
- Devine BJ (1974). Gentamicin therapy and ideal body weight estimation. Drug Intelligence & Clinical Pharmacy.
- Pai MP, Paloucek FP (2000). The origin of the "ideal" body weight equations. Annals of Pharmacotherapy.
- Academy of Nutrition and Dietetics — Healthy weight, body composition, and disease risk
- WHO Expert Consultation (2004). Appropriate body-mass index for Asian populations. The Lancet.
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