What is ideal body weight?

Ideal body weight (IBW) is an estimated weight range considered healthy for a given height and gender. It is calculated using medically established formulas including Hamwi (1964), Devine (1974), Robinson (1983), and Miller (1983). These were originally developed for clinical drug dosing but are now widely used as general health references. According to a review in the Annals of Pharmacotherapy, the Devine formula is used by over 90% of hospital pharmacists for weight-based medication dosing. For personal health goals, the healthy BMI range (18.5-24.9) endorsed by the WHO typically provides a more appropriate target than any single-formula IBW estimate.

Which ideal weight formula is most accurate?

No single formula is universally the most accurate because ideal weight depends on body composition, bone density, muscle mass, and individual health factors. The Devine formula is the most commonly used in clinical settings for drug dosing and ventilator calculations. The Robinson and Miller formulas tend to produce lower estimates for taller individuals, which some researchers consider more realistic for modern populations. A 2016 study comparing all four formulas found that the Robinson formula most closely matched measured lean body mass in a sample of 1,800 adults. Comparing results from all formulas gives you a 3-8 kg range that accounts for formula variation.

How does BMI relate to ideal weight?

BMI (Body Mass Index) provides a weight range based on your height, calculated as weight in kg divided by height in meters squared. The WHO defines a healthy BMI as 18.5-24.9. For a 5'10" person, this corresponds to 129-174 lbs (58.5-79.0 kg) -- a much wider range than the formula-based ideal weights of 157-166 lbs. The BMI range accommodates natural variation in body types, while formula IBW provides a single target point. This calculator shows both approaches so you can see where the formula estimates fall within the healthy BMI band. Use the BMI calculator to see which category your current weight falls into.

Can ideal weight calculators account for muscle mass?

No, standard ideal weight formulas do not account for muscle mass, bone structure, or body fat percentage. Athletes and individuals with high muscle mass frequently weigh 10-20% more than their calculated ideal weight while maintaining excellent cardiovascular health and low body fat. For example, a 6'0" male bodybuilder at 100 kg (220 lbs) has a BMI of 30.0 ("obese" by definition) but may have only 12% body fat. This is why the American College of Sports Medicine recommends using body fat percentage alongside BMI and IBW for fitness assessments. Use the body fat calculator for a more complete picture of body composition.

Does ideal weight change with age?

None of the four standard IBW formulas account for age, but research suggests the healthiest weight may change as you age. A large meta-analysis published in JAMA found that adults over 65 with BMIs of 25-27 (technically "overweight") had slightly lower mortality rates than those at BMI 18.5-24.9. This may be because modest extra weight provides metabolic reserves during illness. Additionally, adults naturally lose muscle mass after age 30 (approximately 3-8% per decade), meaning the same weight may represent more fat and less muscle over time. The TDEE calculator accounts for age when estimating caloric needs.

Ideal Weight Calculator

Unit System

Height (cm)

Gender

Hamwi Formula

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Devine Formula

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Robinson Formula

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Miller Formula

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Healthy BMI Range (18.5–24.9)

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How the Ideal Weight Calculator Works

Ideal weight is an estimated body weight range considered healthy for a given height and gender, calculated using medically established formulas. This calculator compares four well-known formulas developed over several decades -- Hamwi (1964), Devine (1974), Robinson (1983), and Miller (1983) -- alongside the healthy BMI range endorsed by the World Health Organization (WHO). Each produces a slightly different estimate, reflecting the reality that no single "perfect weight" exists for any given height.

According to the Centers for Disease Control and Prevention (CDC), 41.9% of U.S. adults had obesity in 2022, making weight assessment tools increasingly important for public health. However, these formulas have limitations -- they do not account for muscle mass, bone density, ethnic variations, or age. The ideal body weight calculator focuses specifically on the Devine formula used in clinical settings, while this tool provides a broader multi-formula comparison.

The Ideal Weight Formulas

All four formulas use height (in inches over 5 feet) and gender as inputs. The formulas were originally published in medical journals for clinical drug dosing and nutritional assessment.

Hamwi (1964): Males = 48.0 kg + 2.7 kg/inch over 5 ft; Females = 45.5 kg + 2.2 kg/inch over 5 ft
Devine (1974): Males = 50.0 kg + 2.3 kg/inch over 5 ft; Females = 45.5 kg + 2.3 kg/inch over 5 ft
Robinson (1983): Males = 52.0 kg + 1.9 kg/inch over 5 ft; Females = 49.0 kg + 1.7 kg/inch over 5 ft
Miller (1983): Males = 56.2 kg + 1.41 kg/inch over 5 ft; Females = 53.1 kg + 1.36 kg/inch over 5 ft
Healthy BMI Range: Weight (kg) = BMI x height(m)², using BMI 18.5-24.9

Worked example (5'8" male): Hamwi = 48.0 + 2.7(8) = 69.6 kg (153 lbs). Devine = 50.0 + 2.3(8) = 68.4 kg (151 lbs). Robinson = 52.0 + 1.9(8) = 67.2 kg (148 lbs). Miller = 56.2 + 1.41(8) = 67.5 kg (149 lbs). BMI range = 57.3-77.1 kg (126-170 lbs). The formula range spans 67.2-69.6 kg, a narrow 2.4 kg spread.

Key Terms You Should Know

Body Mass Index (BMI): Weight in kg divided by height in meters squared. The WHO defines underweight as BMI below 18.5, normal weight as 18.5-24.9, overweight as 25-29.9, and obese as 30+. Calculate yours with the BMI calculator.
Body Composition: The proportion of fat, muscle, bone, and water in the body. Two people at the same weight and height can have very different health profiles depending on their fat-to-muscle ratio.
Frame Size: Bone structure varies among individuals. Small-framed people may be healthiest at the lower end of the ideal weight range, while large-framed individuals may be healthiest at the upper end. Wrist circumference and elbow breadth are common frame size indicators.
Lean Body Mass (LBM): Total body weight minus fat mass. LBM includes muscle, organs, bones, and water. Use the lean body mass calculator for this measurement.
Waist-to-Hip Ratio: An alternative health metric that assesses fat distribution. The WHO considers a ratio above 0.90 for men or 0.85 for women to indicate substantially increased metabolic risk, regardless of overall weight. Use the waist-to-hip ratio calculator for this assessment.

Ideal Weight Formulas Comparison (5'10" / 178 cm Example)

Formula	Year	Male Result	Female Result	Method
Hamwi	1964	166 lb (75.3 kg)	155 lb (70.3 kg)	Base + per-inch increment from 5 ft
Devine	1974	166 lb (75.3 kg)	149 lb (67.6 kg)	Clinical pharmacology standard
Robinson	1983	160 lb (72.6 kg)	147 lb (66.7 kg)	Revised Devine with updated data
Miller	1983	157 lb (71.2 kg)	150 lb (68.0 kg)	Lower estimates for taller people
Healthy BMI Range	-	129-174 lb (58.5-79.0 kg)	129-174 lb (58.5-79.0 kg)	WHO BMI 18.5-24.9 range

Results vary by formula. Use the range across methods as a guideline rather than any single number.

Practical Examples

Example 1 -- Average-height woman setting a goal: At 5'5" (165 cm), a woman's ideal weight ranges from 55.6 kg (Devine) to 57.5 kg (Hamwi), or 122-127 lbs across formulas. Her healthy BMI range is 50.4-67.9 kg (111-150 lbs). If she currently weighs 72 kg (159 lbs) with a BMI of 26.4, she would need to lose 4-22 kg depending on whether she targets formula IBW or the upper BMI range. A calorie calculator can help determine the daily intake needed to reach her goal.

Example 2 -- Tall male athlete: A 6'2" (188 cm) male who lifts weights regularly weighs 95 kg (209 lbs). His formula IBW ranges from 78.6-85.8 kg across formulas, and his BMI of 26.9 places him in the "overweight" category. However, with a body fat percentage of 14% (measured via the body fat calculator), he is well within healthy ranges. This illustrates why IBW formulas and BMI alone are insufficient for muscular individuals.

Example 3 -- Comparing formulas for a 5'4" woman: Hamwi = 54.3 kg. Devine = 54.7 kg. Robinson = 55.8 kg. Miller = 58.5 kg. The spread is 4.2 kg (9.3 lbs). The Miller formula gives the highest estimate because it was designed to produce more moderate values for shorter heights. Her healthy BMI range is 47.2-63.5 kg, providing a much wider 16.3 kg band that accommodates different body types and frame sizes.

Tips for Using Ideal Weight Estimates

Use the range, not a single number: No formula is perfectly accurate. The spread across all four formulas (typically 3-8 kg) represents a reasonable target zone. The healthy BMI range provides an even wider band that accounts for individual variation.
Consider body composition: If you exercise regularly and have above-average muscle mass, you may be healthiest at or above the upper end of the ideal weight range. A body fat measurement provides more meaningful information than weight alone.
Factor in age: Research from the CDC suggests that slightly higher BMIs (25-27) may be associated with lower mortality in adults over 65, compared to the standard 18.5-24.9 range. None of the four formulas account for age.
Track trends, not daily numbers: Weight fluctuates 1-3 kg daily due to hydration, food intake, and hormonal cycles. Weekly averages over time are more meaningful than any single weigh-in. The BMR calculator can help estimate caloric needs for gradual weight management.
Discuss with your healthcare provider: These formulas do not account for medical conditions, medications, pregnancy, or individual health history. A qualified professional can provide personalized guidance that these calculators cannot.

Disclaimer: This calculator is for informational purposes only and does not constitute medical or health advice. Always consult a qualified healthcare professional for decisions specific to your situation.