Which ideal weight formula is most accurate for general use?

No single formula is universally most accurate. The Devine formula (1974) is widely used in medicine for drug dosing calculations. The Hamwi formula (1964) is common in dietetics. All four formulas are based on height and gender only and do not account for muscle mass, age, or body frame size. For a more complete picture, compare IBW with BMI and body fat percentage.

Ideal Weight Calculator

Find your ideal weight range using four evidence-based formulas.

Height

ft in

Average (4 formulas)

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Healthy BMI Range

—

kg (BMI 18.5–24.9)

Formula	Ideal Weight

⚖️ What is Ideal Body Weight?

Ideal body weight (IBW) refers to an estimated weight range that is associated with optimal health outcomes for a person of a given height and sex. The concept emerged from actuarial life insurance data in the early 20th century, and several clinically validated formulas have since been developed to estimate it.

Ideal weight formulas are primarily height-based, using the observation that taller individuals naturally carry more mass. They were originally developed for clinical use - particularly for calculating medication doses and nutritional requirements in hospital settings - rather than as cosmetic or aesthetic targets. The four most widely cited formulas are Hamwi (1964), Devine (1974), Robinson (1983), and Miller (1983).

Each formula produces a slightly different result because they were derived from different population samples and statistical methods. None accounts for muscle mass, bone density, age, or frame size. As a result, they are most useful as reference points rather than fixed targets.

An alternative approach is to use the BMI-based healthy weight range (BMI 18.5–24.9), which is derived from the World Health Organization's internationally validated cut-offs. This gives a range rather than a single number, which more honestly reflects the natural variation in healthy body composition across individuals.

When using this calculator, consider the average of all four formula results alongside the healthy BMI range to form a broader picture of where your weight ideally should sit. If your current weight falls within this range and your health markers (blood pressure, blood glucose, cholesterol) are good, focusing on fitness and body composition is often more productive than pursuing a specific number.

📐 Ideal Weight Formulas

All formulas: base + (kg per inch × inches over 5 ft)

Hamwi - Men: 48 kg + 2.7 kg/inch | Women: 45.5 kg + 2.2 kg/inch

Devine - Men: 50 kg + 2.3 kg/inch | Women: 45.5 kg + 2.3 kg/inch

Robinson - Men: 52 kg + 1.9 kg/inch | Women: 49 kg + 1.7 kg/inch

Miller - Men: 56.2 kg + 1.41 kg/inch | Women: 53.1 kg + 1.36 kg/inch

Healthy BMI range = height(m)² × 18.5 to height(m)² × 24.9

📖 How to Use This Calculator

Steps

Select your gender - the formulas have different base weights for males and females.

Choose cm or ft/in for height input.

Enter your height accurately (no shoes).

Click Calculate to see all four formula results, their average, and your healthy BMI weight range.

💡 Example Calculations

Example 1 — Male, 178 cm (5 ft 10 in)

Inches over 5 ft: 70 − 60 = 10 inches

Hamwi: 48 + 2.7 × 10 = 75.0 kg | Devine: 50 + 2.3 × 10 = 73.0 kg | Robinson: 52 + 1.9 × 10 = 71.0 kg | Miller: 56.2 + 1.41 × 10 = 70.3 kg

Average ideal weight: 72.3 kg | Healthy BMI range: 58.6 – 78.9 kg

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Example 2 — Female, 163 cm (5 ft 4 in)

Inches over 5 ft: 64.2 − 60 = 4.2 inches

Hamwi: 45.5 + 2.2 × 4.2 = 54.7 kg | Devine: 45.5 + 2.3 × 4.2 = 55.2 kg | Robinson: 49 + 1.7 × 4.2 = 56.1 kg | Miller: 53.1 + 1.36 × 4.2 = 58.8 kg

Average ideal weight: 56.2 kg | Healthy BMI range: 49.2 – 66.2 kg

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Frequently Asked Questions

Which ideal weight formula is most accurate?+

No formula is universally most accurate, as they were each derived from different populations and methods. The Devine formula (1974) is widely used in clinical medicine for drug dosing. Robinson and Miller refined Devine's work. Hamwi (1964) is commonly used by dietitians. Research suggests that viewing the average of all four formulas, and considering the BMI-based healthy range, gives the most useful perspective for general health.

What is the difference between the four formulas?+

All four formulas start from a base weight at 5 feet (152.4 cm) and add weight per inch over 5 feet. Hamwi: men start at 48 kg (+2.7/inch); women 45.5 kg (+2.2/inch). Devine: men 50 kg (+2.3/inch); women 45.5 kg (+2.3/inch). Robinson: men 52 kg (+1.9/inch); women 49 kg (+1.7/inch). Miller: men 56.2 kg (+1.41/inch); women 53.1 kg (+1.36/inch). They produce similar but not identical results.

What is a healthy weight range based on BMI?+

A healthy BMI is 18.5 to 24.9. To find your healthy weight range from BMI: multiply your height in metres squared by 18.5 (lower limit) and by 24.9 (upper limit). For example, at 170 cm (1.70 m): lower = 1.70² × 18.5 = 53.5 kg, upper = 1.70² × 24.9 = 71.9 kg. This range is often wider than individual formula outputs.

Do ideal weight formulas account for muscle mass?+

No. All circumference- and height-based formulas assume an average body composition. Bodybuilders, athletes, or very muscular individuals may legitimately weigh significantly more than these formulas suggest while having excellent health. Conversely, someone with low muscle mass may be within the 'ideal' range but have poor body composition. Use body fat percentage alongside ideal weight for a fuller picture.

Should I try to reach my calculated ideal weight?+

Not necessarily. These formulas provide a statistical reference point derived from population studies. Individual factors like frame size, muscle mass, age, and metabolic health all matter. A weight that falls slightly outside the calculated ideal but where you feel energetic, your health markers are good, and you can sustain your lifestyle is preferable to rigidly chasing a number.

How does frame size affect ideal weight calculations?+

Standard ideal weight formulas (Devine, Hamwi, Robinson, Miller) do not account for frame size, which is a known limitation. A large-framed individual naturally carries more bone and muscle mass and may legitimately weigh 5–10% above a formula's output while still being healthy. A small-framed person may be at their healthiest near the lower end of the formula range. Frame size is estimated by measuring wrist circumference relative to height - larger wrist-to-height ratios indicate a larger frame.

Can your ideal weight differ from your BMI normal weight range?+

Yes. IBW formulas and BMI produce different estimates. For a 173 cm man, BMI normal range (18.5-24.9) gives 55-74 kg, while IBW formulas give approximately 68-72 kg. IBW formulas tend to be more specific than the broad BMI normal range. Athletes with high muscle mass may exceed IBW while maintaining excellent health.

Should I use ideal weight or BMI to set my health goal?+

Both are rough screening tools with limitations. BMI ignores body composition (a muscular athlete may have a high BMI but low body fat), while ideal weight formulas are based on population averages that do not account for frame size or muscle mass. A better approach is to combine multiple indicators: BMI, waist circumference, body fat percentage, and waist-to-height ratio. Consulting a healthcare professional gives personalised targets based on your full health profile.

How does frame size affect ideal body weight?+

Frame size (small, medium, large) accounts for differences in bone density and structure. The Hamwi formula has built-in frame size adjustments: subtract 10% for small frame, add 10% for large frame. A large-frame person may healthily weigh 10-15 kg more than a small-frame person of the same height. Frame size can be estimated by wrapping your thumb and middle finger around your wrist - if they overlap, small frame; if they touch, medium; if they do not touch, large frame.

🔗 Related Calculators

📌 Quick Tips

💡No single ideal weight formula is perfect for everyone. Athletes, older adults, and people with different body frames will all have different optimal weights. Use the range as a guide, not a rigid target.

💡The healthy BMI range (18.5–24.9) translates to a weight range at your height. This is often more useful than a single 'ideal' number because it acknowledges natural variation.

💡Focus on health markers - blood pressure, blood glucose, energy levels, fitness - rather than hitting a specific number on the scale. Weight is one of many health indicators.