Which ideal body weight formula is the most accurate?

No single formula is universally most accurate — they were each developed from different populations and for different purposes: • Devine (1974): Most widely used clinically. Originally developed to calculate drug doses. Best validated for average-height adults. • Robinson (1983): Considered a refinement of Devine with a slightly different slope. Good general-purpose formula. • Miller (1983): Based on Metropolitan Life Insurance height-weight tables. Tends to give higher values for tall individuals. • Hamwi (1964): Oldest formula. Still used in endocrinology and diabetes management. Explicitly allows ±10% for small or large frame. • BMI Method: Most intuitive — uses the midpoint of the WHO healthy range (BMI 21.5). Technically most defensible as it directly reflects WHO health standards. For most purposes, the average of the four clinical formulas (Devine, Robinson, Miller, Hamwi) is the best single estimate. The healthy BMI range (18.5–24.9) is the most widely accepted scientific standard.

What is the difference between ideal body weight and healthy weight?

Ideal body weight (IBW) and healthy weight range are related but different concepts: Ideal Body Weight (IBW) gives a single target number from a formula. It was originally developed for clinical purposes like drug dosing, not as a lifestyle or fitness target. IBW formulas can give slightly different values and do not account for individual variation in muscle mass, bone density, or body composition. Healthy Weight Range is defined by WHO as BMI 18.5 to 24.9. It gives a range of weights, not a single target, and is more appropriate for general wellness and health risk assessment. For a 175cm person, this is 56.7–76.3 kg — a 20 kg range. Key distinction: Someone with significant muscle mass (like an athlete) might have an 'overweight' BMI but be at an ideal weight for their body composition. IBW and BMI both have limitations for highly muscular individuals.

How does body frame size affect ideal weight?

The Hamwi formula explicitly accounts for frame size by allowing a ±10% adjustment: • Small frame: subtract 10% from IBW • Medium frame: use IBW as calculated • Large frame: add 10% to IBW How to estimate frame size using wrist circumference (most common clinical method): For women 5'2" to 5'5": • Small frame: wrist 5.75 inches For men over 5'5": • Small frame: wrist 5.5 to 6.5 inches • Medium frame: wrist 6.5 to 7.5 inches • Large frame: wrist > 7.5 inches The other three formulas (Devine, Robinson, Miller) do not explicitly adjust for frame, though body frame is implicitly reflected in actual body weight and composition.

What is Adjusted Body Weight and when is it used?

Adjusted Body Weight (AdjBW) is used in clinical medicine for medication dosing in patients who are obese (BMI > 30). Formula: AdjBW = IBW + 0.4 × (Actual Weight − IBW) Rationale: In obese patients, using actual body weight for drug dosing can result in overdosing because some drugs distribute mainly in lean tissue, not fat. Using IBW alone can underdose because obese patients still have more lean mass than predicted by IBW. The 0.4 factor accounts for the fact that roughly 40% of excess weight above IBW consists of metabolically active tissue. Common uses: Aminoglycoside antibiotics (gentamicin, tobramycin), vancomycin, heparin, digoxin, and some chemotherapy agents. Example: Patient weighs 100 kg, IBW = 70 kg AdjBW = 70 + 0.4 × (100 − 70) = 70 + 12 = 82 kg Important: Drug dosing should always be supervised by a qualified healthcare professional. This calculator provides informational values only.

Do ideal body weight formulas work for very short or very tall people?

The four clinical formulas (Devine, Robinson, Miller, Hamwi) were all calibrated for people near average height and become less reliable at extremes: Below 5 feet (152 cm): All formulas break down because they were not validated for very short adults. Below 5ft the formulas may produce unrealistically low or even negative values. Above 6'3" (190 cm): The linear per-inch increment tends to overestimate ideal weight for very tall people. Taller people generally do not need proportionally more weight per additional inch of height. For height extremes, the BMI method (IBW = target BMI × height²) is more appropriate, since it uses a height squared relationship rather than a linear one. The healthy BMI range (18.5–24.9) is valid across all heights. This is one reason why the Ponderal Index (weight/height³) is sometimes preferred for very tall or very short people — it corrects for the fact that weight does not scale linearly with height.

Should I try to reach my ideal body weight?

Not necessarily — IBW is a clinical tool, not a personal fitness target. A few important points: 1. Sustainable matters more than ideal: Losing weight to the calculated IBW and maintaining it long-term is far more valuable than reaching an exact number temporarily. Modest weight loss (5–10% of body weight) provides significant health benefits. 2. Muscle vs fat: If you exercise regularly and have good muscle mass, your 'ideal' weight based on formulas may be lower than what is healthy for you. Athletes and muscular individuals appropriately weigh more than IBW predicts. 3. Healthy range > single target: The healthy weight range (BMI 18.5–24.9) is scientifically better supported than any single IBW formula. Being anywhere in this range is associated with healthy outcomes. 4. Consult a professional: For personalised weight management, a registered dietitian or physician can account for your individual body composition, health history, and goals — far beyond what any formula can capture.

Ideal Body Weight Calculator — Devine, Robinson, Miller & Hamwi

The Ideal Body Weight Calculator computes your ideal weight using all four major clinical formulas — Devine (1974), Robinson (1983), Miller (1983), and Hamwi (1964) — plus the BMI Method using the midpoint of the WHO healthy range. Results are shown in both kg and lbs, with the average of the four formulas highlighted ..

YOUR MEASUREMENTS

HEIGHT

= 5ft 8.9in

YOUR CURRENT WEIGHT (kg) — optional

Enter your actual weight to see how far you are from ideal and get an adjusted body weight if needed.

IDEAL BODY WEIGHT — ♂ MALE

AVERAGE (4 FORMULAS)

70.0

DEVINE

70.5

ROBINSON

68.9

MILLER

68.7

HAMWI

72.0

BMI METHOD (21.5)

65.8

HEALTHY RANGE

56.7–76.3

kg (BMI 18.5–24.9)

FORMULA COMPARISON (KG)

FULL COMPARISON

Devine (1974)

Most used in clinical medicine

70.5 kg

Robinson (1983)

Refined from Devine

68.9 kg

Miller (1983)

Based on Metropolitan Life tables

68.7 kg

Hamwi (1964)

Frame-size approach, oldest formula

72.0 kg

BMI Method (21.5)

Midpoint of normal BMI range

65.8 kg

Average (4 formulas)

Best single estimate

70.0 kg

Healthy min

BMI 18.5 lower boundary

56.7 kg

Healthy max

BMI 24.9 upper boundary

76.3 kg

Created with❤️byeaglecalculator.com

HOW TO USE

1
Select your unit system (Metric kg/cm or Imperial lbs/ft in) and biological sex. Sex matters because the four clinical formulas were derived from different baseline body compositions: at the same height, the male IBW baseline is approximately 4–6.5 kg higher than female, reflecting differences in lean mass and bone density.
2
Enter your height. In metric, type centimetres directly. In imperial, enter feet and inches in separate fields. The calculator shows the equivalent in the other system below the input. All four formulas are based on height above 5 feet (60 inches / 152.4 cm) — the formulas still work below 5ft but with decreasing accuracy.
3
Read the results: the large number is the average of the four clinical formulas (Devine, Robinson, Miller, Hamwi) — this is the best single estimate. Below it you see each formula individually, plus the BMI Method result (using BMI 21.5, the midpoint of the healthy range), and the full healthy weight range for your height (BMI 18.5 to 24.9).
4
Optionally enter your current actual weight to unlock the comparison view. The calculator will show how far you are above or below ideal, display the 'Actual vs Ideal Position' bar showing both your current BMI and ideal BMI side by side, and — if your BMI is above 30 — calculate your Adjusted Body Weight (used for medication dosing).
5
Check the formula comparison bar chart to see the spread between all five methods. All four clinical formulas generally agree within 3–5 kg for most heights. Large disagreements between formulas usually indicate the person is at a height extreme (very short or very tall), where BMI-based approaches may be more reliable.

WORKED EXAMPLE

Ideal Body Weight for a 175cm (5ft 9in) male: Height in inches: 5 × 12 + 9 = 69 inches Excess over 60 inches: 69 − 60 = 9 inches DEVINE formula: IBW = 50 + 2.3 × 9 = 50 + 20.7 = 70.7 kg (155.9 lbs) ROBINSON formula: IBW = 52 + 1.9 × 9 = 52 + 17.1 = 69.1 kg (152.3 lbs) MILLER formula: IBW = 56.2 + 1.41 × 9 = 56.2 + 12.7 = 68.9 kg (151.9 lbs) HAMWI formula: IBW = 48 + 2.7 × 9 = 48 + 24.3 = 72.3 kg (159.4 lbs) Average of 4 formulas: (70.7 + 69.1 + 68.9 + 72.3) / 4 = 70.3 kg BMI METHOD (target BMI 21.5): Height in metres: 175 / 100 = 1.75 m IBW = 21.5 × 1.75² = 21.5 × 3.0625 = 65.8 kg Healthy weight range (BMI 18.5–24.9): Min: 18.5 × 1.75² = 56.7 kg (125 lbs) Max: 24.9 × 1.75² = 76.3 kg (168 lbs) If actual weight is 95 kg (BMI 31.0): Adjusted BW = 70.7 + 0.4 × (95 − 70.7) = 70.7 + 9.7 = 80.4 kg

REFERENCE FORMULAS

FORMULA REFERENCE TABLE

Name	Formula (kg)	Description
Devine (1974) — Male	IBW = 50 + 2.3 × (H_in − 60)	H_in = height in inches. Most widely used in clinical medicine and drug dosing.
Devine (1974) — Female	IBW = 45.5 + 2.3 × (H_in − 60)	Same slope as male formula, lower base weight.
Robinson (1983) — Male	IBW = 52 + 1.9 × (H_in − 60)	Published in JPEN. Slightly steeper base, shallower slope than Devine.
Robinson (1983) — Female	IBW = 49 + 1.7 × (H_in − 60)	Widely cited in nutrition research.
Miller (1983) — Male	IBW = 56.2 + 1.41 × (H_in − 60)	Based on Metropolitan Life Insurance height-weight tables.
Miller (1983) — Female	IBW = 53.1 + 1.36 × (H_in − 60)	Gives higher baseline but lower per-inch increment.
Hamwi (1964) — Male	IBW = 48 + 2.7 × (H_in − 60)	Oldest formula. Used in endocrinology. Allows ±10% for body frame.
Hamwi (1964) — Female	IBW = 45.4 + 2.2 × (H_in − 60)	Clinically used for diabetic patients. Frame adjustment: ±10%.
BMI Method	IBW = target_BMI × height(m)²	Target BMI = 21.5 (midpoint of 18.5–24.9 normal range). Most intuitive.
Adjusted BW (obese)	AdjBW = IBW + 0.4 × (Actual − IBW)	Used for medication dosing when BMI > 30. Accounts for excess fat mass.

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Last updated: April 28, 2026 · Formulas: Devine (1974), Robinson (1983), Miller (1983), Hamwi (1964) · Eagle-eyed accuracy for every calculation.