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What Is Ideal Body Weight?

Ideal body weight (IBW) is a formula-derived weight target based primarily on height and sex. It originated not in public health but in pharmacology — clinicians needed a consistent way to dose medications (particularly renally-cleared drugs) that are distributed through lean body mass rather than total body mass.

The four main IBW formulas (Devine, Hamwi, Robinson, Miller) were developed between 1964 and 1983. None of them were validated against body composition data or long-term health outcomes. They were practical approximations for a clinical dosing problem. Interpreting them as aspirational fitness targets requires significant context.

See all four formulas side by side for your height: use our ideal weight calculator. For the full healthy weight range (BMI 18.5–24.9), use our healthy weight calculator.

The Four Ideal Weight Formulas

All four formulas use height in inches above 5 feet (60 inches) as the primary variable. Heights below 5 feet are handled differently by each formula.

Devine (1974): Males = 50 kg + 2.3 kg per inch over 60. Females = 45.5 kg + 2.3 kg per inch over 60. Most widely used in clinical pharmacokinetics.
Hamwi (1964): Males = 106 lb + 6 lb per inch over 60. Females = 100 lb + 5 lb per inch over 60. Oldest formula; used in clinical nutrition.
Robinson (1983): Males = 52 kg + 1.9 kg per inch over 60. Females = 49 kg + 1.7 kg per inch over 60. Tends to give slightly lower estimates than Devine.
Miller (1983): Males = 56.2 kg + 1.41 kg per inch over 60. Females = 53.1 kg + 1.36 kg per inch over 60. Gives the highest estimates among the four for taller individuals.

Example for a 5′10″ male (70 inches = 10 inches over 60):
Devine: 50 + (2.3 × 10) = 73 kg (161 lb). Hamwi: 106 + (6 × 10) = 166 lb. Robinson: 52 + (1.9 × 10) = 71 kg (157 lb). Miller: 56.2 + (1.41 × 10) = 70.3 kg (155 lb).

Ideal weight formula comparison showing Devine, Hamwi, Robinson and Miller results by height for men and women

Formula Comparison by Height (Male)

Height	Devine	Hamwi	Robinson	Miller
5′6″ (168 cm)	64 kg (141 lb)	142 lb	63 kg (139 lb)	64 kg (141 lb)
5′8″ (173 cm)	69 kg (151 lb)	154 lb	67 kg (147 lb)	67 kg (148 lb)
5′10″ (178 cm)	73 kg (161 lb)	166 lb	71 kg (157 lb)	70 kg (155 lb)
6′0″ (183 cm)	78 kg (172 lb)	178 lb	75 kg (166 lb)	74 kg (163 lb)
6′2″ (188 cm)	83 kg (182 lb)	190 lb	79 kg (175 lb)	77 kg (170 lb)

IBW vs. BMI-Based Healthy Weight

IBW formulas and BMI-based healthy weight ranges give different answers, and neither is inherently "right." Understanding the difference helps:

IBW formulas give a single number — a clinical point estimate. They were designed for pharmacokinetic dosing, not as a fitness goal. A Devine IBW for a 5′10″ male is 73 kg (161 lb).
BMI healthy range (18.5–24.9) gives a range: for a 5′10″ male, that is 58.5–79 kg (129–174 lb). The IBW falls inside this range but toward the lower end.
Both ignore body composition. A muscular 5′10″ male at 185 lb with 12% body fat is healthier than a lean 5′10″ male at 150 lb with 30% body fat due to sarcopenic obesity.

Check your current BMI with our BMI calculator and your body fat percentage with our body fat calculator. Track lean mass changes with our lean body mass calculator.

Body Composition: The Missing Context

What you weigh matters less than what that weight is made of. Two people at identical IBW can have radically different health profiles based on their fat-to-muscle ratio.

Healthy body fat % (men): 10–20% (fitness: 6–17%, athletes: 6–13%)
Healthy body fat % (women): 20–30% (fitness: 16–25%, athletes: 14–20%)
Overfat: Men >25%, Women >35% — associated with metabolic dysfunction even at "normal" weight

The clinically accurate picture combines weight target, body fat percentage, and lean mass preservation. For anyone doing resistance training, IBW and even BMI will underestimate a healthy target weight.

Setting a Realistic Weight Target

Rather than targeting a specific IBW number, use this layered approach:

Step 1: Find your BMI healthy range (18.5–24.9) for your height using our healthy weight calculator. This is your broad target window.
Step 2: Estimate your current body fat percentage using our body fat calculator.
Step 3: Calculate your lean body mass using our lean body mass calculator. Your target weight = LBM ÷ (1 − target body fat fraction).
Step 4: Cross-check that your target weight falls within your BMI 18.5–24.9 healthy range. If it does not (common for muscular individuals), prioritize the body composition target over the BMI range.

Example: 5′10″ male, current weight 200 lb, 25% body fat. LBM = 150 lb. Target body fat = 15%. Target weight = 150 ÷ 0.85 = 176 lb — above IBW formulas but perfectly appropriate for a muscular frame.

Common Ideal Weight Mistakes

Using IBW as an absolute target rather than a reference

IBW formulas were developed for medication dosing and give a single point estimate. In clinical practice they are used alongside other measures. Treating Devine IBW as the exact weight you must achieve ignores body frame, muscle mass, and individual variation.

Ignoring frame size adjustments

The Hamwi formula includes a ±10% adjustment for small or large body frame. Large-framed individuals are typically 10% above the base IBW; small-framed individuals are 10% below. Ignoring frame gives a distorted target.

Setting a goal below IBW to look more athletic

Looking more muscular and weighing less than IBW are contradictory goals for most people. Muscle is denser than fat — a muscular person usually weighs more than IBW, not less.

Comparing across sexes

The male and female versions of IBW formulas have different baseline weights and different increment rates per inch. Never apply the male formula to a female or vice versa.

Ideal Weight FAQs

Which ideal weight formula is most accurate?

No single formula is universally most accurate for healthy weight prediction. Devine and Robinson are most widely used in clinical settings. The average of all four formulas reduces the bias of any single one. For practical purposes, the BMI healthy weight range (18.5–24.9) and a target body fat percentage together give more actionable guidance.

What should I weigh for my height?

There is no single answer. As a starting point: find the BMI 18.5–24.9 range for your height, which gives the weight range most consistently associated with low chronic disease risk in population studies. Factor in your muscle mass, frame size, and fitness goals to set a personal target within or above that range.

Is it healthy to be below IBW?

Being significantly below IBW (>10%) suggests underweight status, which is associated with malnutrition, bone density loss, immune suppression, and hormonal disruption. BMI below 18.5 is classified as "mild thinness" and below 17 as "moderate thinness" with associated health risks.

How does age affect ideal weight?

IBW formulas do not adjust for age. In practice, slight increases in weight with age (particularly in the BMI 22–27 range) are associated with better survival outcomes in adults over 65 compared to lower BMI values. Muscle mass preservation becomes more important than absolute weight as we age.

Ideal Weight Calculator Guide: Which Formula Is Right for You?