Ideal Weight Calculator
Calculate your ideal body weight using multiple formulas (Devine, Robinson, Miller). Get healthy weight range based on height, age, and gender. Free tool.
Reviewed by CalculatorApp.me Health Team
Ideal Weight Calculator — Complete Guide
Hamwi, Devine, Robinson, and Miller formulas, healthy BMI weight ranges, and clinical interpretation of ideal body weight.
4
IBW formulas compared
18.5–24.9
Healthy BMI weight range
±10%
Normal frame size variation
2.3 kg
Per inch over 5 ft (Hamwi men)
What Is Ideal Body Weight (IBW)?
Ideal Body Weight (IBW) refers to a target body weight associated with optimal health outcomes for a given height. It is primarily used in clinical medicine for dosing medications, anaesthesia, ventilator settings, and nutritional planning — not as a personal aesthetic target. IBW represents the weight at which health risks from both underweight and overweight are minimised.
Several formulas were developed in the 1960s and 1970s to create quick bedside estimates for clinical use. The most common — Hamwi, Devine, Robinson, and Miller — were not derived from large epidemiological datasets but from clinical observations. Today, they are best used as starting estimates, with BMI-based healthy ranges providing a more evidence-based complement.
It is important to recognise that "ideal weight" is a range, not a single number. Two people of the same height can have very different optimal weights depending on muscle mass, bone density, age, sex, and ethnicity. Frame size — whether small, medium, or large — can shift ideal weight by 10% in either direction.
Ideal Body Weight Formulas
Men: IBW = 48 kg + 2.7 kg per inch over 5 ft Women: IBW = 45.5 kg + 2.2 kg per inch over 5 ft Examples: Man, 5'10" (70 inches → 10 inches over 5 ft): IBW = 48 + 2.7(10) = 48 + 27 = 75 kg IBW range = 67.5 – 82.5 kg (±10%) Woman, 5'5" (65 inches → 5 inches over 5 ft): IBW = 45.5 + 2.2(5) = 45.5 + 11 = 56.5 kg IBW range = 50.9 – 62.2 kg (±10%) Under 5 ft: Men: 48 − 2.7 × (60 − height in inches) Women: 45.5 − 2.2 × (60 − height in inches)
The Hamwi formula was developed for clinical use by diabetologist G.J. Hamwi in 1964. It is still the most commonly used IBW formula in hospitals and clinical nutrition practice.
Men: IBW = 50 kg + 2.3 kg per inch over 5 ft Women: IBW = 45.5 kg + 2.3 kg per inch over 5 ft Note: Same as Hamwi for women; slightly different for men (+2.3 vs +2.7/inch) Examples: Man, 6'0" (72 inches → 12 inches over 5 ft): IBW = 50 + 2.3(12) = 50 + 27.6 = 77.6 kg Woman, 5'8" (68 inches → 8 inches over 5 ft): IBW = 45.5 + 2.3(8) = 45.5 + 18.4 = 63.9 kg Most commonly cited in pharmacokinetics for drug dosing, particularly renal clearance calculations and anaesthesia.
The Devine formula was published in a Drug Intelligence paper and became widely adopted for pharmacokinetic drug dosing. It is still the standard for creatinine clearance estimation and anaesthesia weight-based dosing.
Men: IBW = 52 kg + 1.9 kg per inch over 5 ft Women: IBW = 49 kg + 1.7 kg per inch over 5 ft Examples: Man, 5'10" (10 inches over 5 ft): IBW = 52 + 1.9(10) = 52 + 19 = 71 kg Woman, 5'6" (6 inches over 5 ft): IBW = 49 + 1.7(6) = 49 + 10.2 = 59.2 kg Comparison at 5'10" male: Hamwi: 75 kg | Devine: 72.6 kg Robinson: 71 kg | Miller: 68 kg Robinson tends to give lower estimates than Hamwi and Devine, particularly for taller individuals.
Robinson et al. derived this formula in 1983 from a large dataset of adults. It generally gives more conservative (lower) weight targets than Hamwi, which some researchers consider more appropriate for most body types.
Healthy weight = BMI 18.5–24.9 Weight range for BMI 18.5–24.9: Weight (kg) = BMI × height² (m²) Example: 5'10" = 1.78 m: Lower (BMI 18.5): 18.5 × 1.78² = 58.6 kg Upper (BMI 24.9): 24.9 × 1.78² = 78.9 kg Healthy range: 58.6 – 78.9 kg Example: 5'5" = 1.65 m: Lower (BMI 18.5): 18.5 × 1.65² = 50.3 kg Upper (BMI 24.9): 24.9 × 1.65² = 67.7 kg Healthy range: 50.3 – 67.7 kg BMI-range approach is most consistent with WHO and CDC health guidance.
The BMI 18.5–24.9 approach gives a range rather than a single target, which better reflects the reality that optimal weight varies significantly within the same height due to body composition differences.
Adjusting for Frame Size
Small Frame
Subtract 10%
Wrist circumference smaller than typical for height; visible bone structure
Medium Frame
Use IBW as-is
Wrist circumference within typical range; average bone density
Large Frame
Add 10%
Wrist circumference larger than typical; dense bone structure
Wrist Circumference Method
Women (height > 5'5") Men Wrist < 6.0" → Small Wrist < 6.5" → Small Wrist 6.0–6.5" → Medium Wrist 6.5–7.5" → Medium Wrist > 6.5" → Large Wrist > 7.5" → Large
Limitations
The Hamwi, Devine, Robinson, and Miller formulas were developed decades ago from limited clinical datasets, primarily for drug dosing and nutritional assessment — not as personal fitness or aesthetic targets. None of them account for body composition, so a muscular or athletic person can exceed every formula's estimate while being at a healthy body fat percentage.
These formulas are not valid for children or adolescents, who require age- and sex-specific growth-chart percentiles (CDC/WHO) interpreted by a pediatrician, not an adult height-weight formula.
This calculator provides a general reference range, not medical advice. Body fat percentage, waist circumference, blood markers, and overall fitness are generally more meaningful health indicators than matching any single ideal-weight number, and anyone with health concerns about their weight should consult a physician or registered dietitian.
Frequently Asked Questions
What is ideal body weight and how is it calculated?▼
Ideal body weight (IBW) is a target weight range associated with good health outcomes for a given height. Clinical formulas — Robinson (1983), Miller (1983), Devine (1974), and Hamwi (1964) — estimate IBW from height alone. The Robinson formula for men: IBW = 52 kg + 1.9 kg per inch over 5 ft; for women: 49 kg + 1.7 kg per inch over 5 ft. These formulas were developed for drug-dosing and clinical assessment, not as cosmetic targets.
Which ideal weight formula is most accurate?▼
No single formula is universally most accurate. The Devine formula (men: 50 + 2.3 kg/inch over 5 ft; women: 45.5 + 2.3 kg/inch over 5 ft) is most commonly used in clinical pharmacy for medication dosing. Robinson and Miller formulas produce similar results. All four formulas ignore body composition — a muscular athlete may exceed formula IBW while being perfectly healthy.
Does body frame size affect ideal weight?▼
Yes. A small-frame individual may weigh 10–15% less than a large-frame counterpart at the same height and still be at their ideal weight. Frame size is estimated by wrist circumference or elbow breadth. Standard IBW formulas assume a medium frame. Larger frames have denser bones and more muscle mass, supporting a higher healthy weight range.
How does ideal weight differ from BMI's healthy range?▼
BMI defines a healthy weight range (18.5–24.9 kg/m²) as a percentage-of-height-squared window, which widens with height. IBW formulas give a single target value per height. For most people the results overlap, but IBW formulas can be narrower and may classify muscular individuals as overweight. BMI is population-level screening; IBW is used for clinical dosing.
Is the Hamwi method still used today?▼
The Hamwi method (men: 106 lb + 6 lb per inch over 5 ft; women: 100 lb + 5 lb per inch over 5 ft) was introduced in 1964 and remains in nursing and clinical textbooks as a quick mental calculation. It tends to produce slightly higher estimates than Robinson or Miller for tall individuals. It is primarily used for rapid bedside nutrition assessments, not fitness planning.
Can ideal weight formulas be applied to athletes or very muscular people?▼
IBW formulas are based on average population data and do not account for muscle mass. A strength athlete may exceed their formula IBW by 15–20% while having low body fat. For muscular individuals, body fat percentage (DEXA, hydrostatic weighing) is a more meaningful metric than IBW or BMI. IBW is best used in clinical pharmacology for adjusting drug doses, not as a fitness target.
How accurate are ideal weight calculators for children?▼
Standard IBW formulas (Robinson, Devine, Miller, Hamwi) were developed for adults and are not valid for children. Pediatric ideal weight uses CDC or WHO growth charts (weight-for-age and BMI-for-age percentiles). A child is considered at a healthy weight between the 5th and 85th percentile for their age and sex. Consult a pediatrician for children's weight assessment.
What is the J.D. Robinson formula and why is it popular?▼
The Robinson formula (1983) is popular in clinical settings for its simplicity and moderate estimates. Men: IBW = 52 kg + 1.9 kg × (height in cm − 152.4) / 2.54; Women: IBW = 49 kg + 1.7 kg × (height in cm − 152.4) / 2.54. Studies show it has the best agreement with newer anthropometric data compared to Devine and Hamwi, making it the preferred formula in adjusted body weight (AdjBW) calculations for obese patients.
What is adjusted body weight and when is it used?▼
Adjusted body weight (AdjBW) is used in clinical nutrition and pharmacokinetics when actual body weight (ABW) exceeds IBW by more than 20–30%. AdjBW = IBW + 0.4 × (ABW − IBW). It accounts for the fact that adipose tissue has lower drug distribution volume than lean tissue, preventing overdosing in obese patients. It is commonly used for aminoglycoside antibiotic dosing and enteral nutrition calculations.
Does gender affect ideal weight calculations?▼
Yes, all major IBW formulas use different constants for men and women to reflect differences in bone density, muscle mass, and body composition. Men have a higher proportion of lean muscle mass for a given height, resulting in higher IBW estimates. The Devine formula, for example, starts at 50 kg for men versus 45.5 kg for women at 5 ft, with the same 2.3 kg/inch increment thereafter.
Should I aim to reach my calculated ideal weight?▼
IBW is a clinical reference, not a personal target. Health is better assessed by body fat percentage, waist circumference (men <40 in / <102 cm; women <35 in / <88 cm), cardiorespiratory fitness, blood markers (glucose, lipids), and blood pressure. A weight that feels sustainable, supports energy levels, and keeps metabolic markers in range is healthier than matching a formula's exact number.
References & Clinical Sources
- Hamwi GJ. Changing dietary concepts. In: Danowski TS (ed), Diabetes Mellitus: Diagnosis and Treatment. 1964.
- Devine BJ. Gentamicin therapy. Drug Intelligence Clin Pharmacy. 1974;8:650–5.
- Robinson JD, et al. Estimation of ideal body weight. Clin Pharmacy. 1983;2:56–8.
- Pai MP, Paloucek FP. The origin of the ideal body weight equations. Ann Pharmacother. 2000;34(9):1066–9.
Methodology, sources & limitations
This calculator uses a published formula and the values entered in the calculator to generate the result.
- Formula
- IBW(male) = 50 + 2.3×(height_in - 60); IBW(female) = 45.5 + 2.3×(height_in - 60)
- Jurisdiction & units
- Intended for US, IN, EU, GB, Global. Supports both units where applicable.
- Assumptions & limitations
- Results are screening or educational estimates based on the inputs you provide. They do not diagnose, treat, or replace advice from a qualified clinician.
- Review status
- Formula and automated QA completed September 9, 2026; independent professional review is pending. Next scheduled review: December 9, 2026.
Validation sources
- Devine BJ (1974)
- Robinson et al. (1983)
- Miller et al. (1983)
- Hamwi GJ (1964)
Ideal Weight Calculator — Answer & Method
Calculate ideal body weight using multiple validated formulas (Devine, Robinson, Miller, Hamwi).
Formula: Devine Formula
IBW(male) = 50 + 2.3×(height_in - 60); IBW(female) = 45.5 + 2.3×(height_in - 60)
Example Calculation
A 5'10" male has an ideal weight of approximately 72.7 kg (160 lbs) by the Devine formula.
Important limitation
This is an educational estimate, not a diagnosis or a substitute for professional medical advice.
Key Facts
- The Devine formula is the most commonly used ideal weight formula in clinical settings.
- Ideal weight calculations are estimates and do not account for muscle mass or body composition.