Ideal Weight Calculator

Calculate your ideal body weight using four medically-recognized formulas: Devine, Robinson, Miller, and Hamwi. Enter your height and gender for an instant estimate in kg or lb.

What is Ideal Weight Calculator?

An ideal weight calculator estimates a target body weight for a given height and gender using formulas developed by medical researchers, most commonly to support drug dosing and general health assessment. This calculator applies four established formulas — Devine, Robinson, Miller, and Hamwi — and averages them to give a single reference estimate, while also showing the broader BMI-based healthy weight range for context.

These formulas date back to the 1960s-1980s, when researchers analyzed population health data to find weight-for-height relationships associated with lower mortality and better health outcomes. The Devine formula, published in 1974, remains the most widely cited in clinical practice today, particularly for calculating medication doses that are weight-dependent. The Robinson (1983) and Miller (1983) formulas refined these estimates using updated actuarial data, while the Hamwi formula (1964) remains popular for its simplicity in quick clinical estimates.

It's important to understand that 'ideal weight' is a population-level statistical estimate, not an individual prescription. Body composition, muscle mass, frame size, and overall fitness all affect what a genuinely healthy weight looks like for any specific person. Athletes and muscular individuals often weigh more than their calculated ideal weight while being in excellent health.

Formula

Devine (1974): Male = 50 + 2.3 × (height in inches − 60); Female = 45.5 + 2.3 × (height in inches − 60)

Robinson (1983): Male = 52 + 1.9 × (height in inches − 60); Female = 49 + 1.7 × (height in inches − 60)

Miller (1983): Male = 56.2 + 1.41 × (height in inches − 60); Female = 53.1 + 1.36 × (height in inches − 60)

Hamwi (1964): Male = 48 + 2.7 × (height in inches − 60); Female = 45.5 + 2.2 × (height in inches − 60)

All results are in kilograms. For heights below 60 inches (5 feet), the additional term is treated as zero.

Example: A 175 cm (68.9 in) male:

Devine = 50 + 2.3 × 8.9 = 70.5 kg

Robinson = 52 + 1.9 × 8.9 = 68.9 kg

Miller = 56.2 + 1.41 × 8.9 = 68.7 kg

Hamwi = 48 + 2.7 × 8.9 = 72.0 kg

Average ≈ 70.0 kg

How to Calculate

Enter your height in centimeters or inches using the unit toggle.
Select your gender, since each formula uses different constants for male and female.
View your average ideal weight estimate, shown in your chosen display unit (kg or lb).
Compare the four individual formula results in the breakdown table below.
Check the healthy BMI-based weight range for additional context alongside the formula estimates.

Example

A 165 cm (65 in) female: Devine = 45.5 + 2.3 × 5 = 57.0 kg; Robinson = 49 + 1.7 × 5 = 57.5 kg; Miller = 53.1 + 1.36 × 5 = 59.9 kg; Hamwi = 45.5 + 2.2 × 5 = 56.5 kg. The average of the four formulas is about 57.7 kg (127 lb), while the BMI-based healthy range for that height is roughly 50.4–67.8 kg.

Key Benefits

Instantly compare four medically-recognized ideal weight formulas side by side
See both a single average estimate and the full breakdown for transparency
Works in metric or imperial units for height, with results shown in kg or lb
Includes the BMI-based healthy weight range for broader context
Useful reference point for fitness planning, nutrition coaching, or general health awareness

Common Mistakes to Avoid

Treating the calculated number as a strict target rather than a general reference estimate
Ignoring body composition — muscle is denser than fat, so muscular people often exceed their 'ideal' weight while being healthy
Applying these adult-only formulas to children or adolescents, where growth charts should be used instead
Picking a single formula's result instead of considering the range across all four
Using the result as medical advice without consulting a healthcare provider for personal health decisions

Pro Tips

Look at the range across all four formulas rather than fixating on one exact number.
Combine this estimate with a body composition or waist-to-hip measurement for a fuller picture of health.
If you have a muscular or larger frame, expect your healthy weight to reasonably exceed the calculated average.
Use the healthy BMI range alongside the formula results as a sanity check.
Discuss any specific weight goals with a healthcare provider, especially if the estimate differs significantly from your current weight.

Key Terms Explained

Ideal Body Weight (IBW): An estimated target weight for a given height and gender, originally developed to support clinical dosing calculations
Devine Formula: The most widely used ideal-weight formula in clinical medicine, published in 1974
Robinson Formula: A 1983 refinement of ideal-weight estimates based on updated actuarial data
Miller Formula: Another 1983 formula offering a slightly different weight-for-height relationship
Hamwi Formula: The oldest (1964) and simplest ideal-weight formula, designed for quick manual estimates
Healthy BMI Range: The weight range corresponding to a Body Mass Index of 18.5–24.9 for a given height

Common Use Cases

General fitness and wellness planning to understand a reasonable target weight range
Healthcare and nutrition professionals cross-checking dosing-related weight estimates
Comparing how different ideal-weight formulas vary for the same height and gender
Setting realistic, medically-grounded weight goals alongside a fitness or nutrition plan
Students and clinicians learning the classic ideal-body-weight formulas used in medicine

Interpreting Your Results

When interpreting your ideal weight results, focus on the range across all four formulas rather than any single number. A spread of a few kilograms between formulas is completely normal and reflects the different datasets each was built from — none of them is definitively 'correct.' The average provides a convenient single reference point, but the individual formula breakdown is more informative for understanding how much the estimates can vary. Remember that these formulas were developed decades ago from population averages and don't account for individual differences in muscle mass, bone density, or frame size. A person with an athletic, muscular build will often weigh more than their calculated ideal weight while being perfectly healthy, since muscle is denser than fat. Similarly, someone with a naturally small frame might be healthy below the calculated estimate. For a fuller picture, compare your ideal weight estimate against the BMI-based healthy range shown alongside it. If your current weight falls within the healthy BMI range but above your calculated 'ideal' weight, that's not necessarily a cause for concern — it simply reflects the limitations of formulas that use only height and gender as inputs. Use this tool as a starting point for a conversation with a healthcare provider, not as a final verdict on your health.

Related Concepts

Body Mass Index: BMI provides a broader healthy-weight range based on height alone, complementing the specific target numbers from ideal-weight formulas. Our BMI calculator shows where you fall on that scale with a full visual breakdown.
Daily Calorie Needs: Once you have a target weight in mind, understanding your daily calorie needs helps you plan how to reach or maintain it. Our calorie calculator estimates your daily energy needs based on your stats and activity level.
Food and Nutrition Tracking: Reaching a healthy weight involves nutrition as much as the number on the scale. Our food calories calculator helps you understand the calorie content of everyday foods.
Intermittent Fasting: Some people use structured eating windows to help manage weight. Our intermittent fasting calculator helps plan fasting and eating windows around your schedule.
Water Intake: Hydration is a key part of any weight-management or fitness plan. Our water intake calculator estimates your daily water needs based on your body weight and activity level.

Frequently Asked Questions

What is ideal body weight?

Ideal body weight (IBW) is an estimate of the weight considered optimal for health, based on height and gender. It originated in medicine to help dose medications accurately (many drugs are dosed by body weight) and has since become a general wellness reference point. It's an estimate, not a diagnosis — actual healthy weight varies with muscle mass, bone density, body composition, and individual health factors.

Which formula is most accurate?

No single formula is universally 'most accurate' — they were each developed for different purposes and populations. The Devine formula (1974) is the most widely used in clinical medicine, especially for drug dosing. Robinson (1983) and Miller (1983) are refinements based on updated actuarial data. Hamwi (1964) is the oldest and simplest, popular for quick bedside estimates. Most clinicians look at the average of multiple formulas alongside BMI and body composition rather than relying on one number.

Why do the formulas give different results?

Each formula was derived from different population datasets and study periods, using slightly different baseline weights and per-inch increments above 5 feet. Devine tends to give a slightly lower result than Miller for the same height, for example. The differences are usually small (a few kilograms) but can matter for precise medical calculations like drug dosing, where the specific formula requested by a clinician should be used.

Do these formulas work for children?

No. Devine, Robinson, Miller, and Hamwi were all developed using adult population data and are only valid for adults (typically 18+ with a height at or above 5 feet / 152 cm). For children and adolescents, healthcare providers use growth charts and pediatric-specific percentile curves instead, since children's healthy weight changes continuously with age and growth stage.

How is ideal weight different from BMI healthy range?

Ideal body weight formulas give a single target number for a given height and gender. The BMI-based healthy range (18.5–24.9) gives a broader range of weights considered healthy for that height, regardless of gender. Both are population-level estimates and don't account for muscle mass — a muscular athlete can have a 'high' BMI or exceed their calculated ideal weight while being perfectly healthy.

Should I try to reach my calculated ideal weight exactly?

Not necessarily. These formulas are estimates meant to give a reference point, not a strict target. Healthy weight depends on muscle mass, frame size, body composition, and overall fitness — not just height and gender. Use the result as a general guide alongside advice from a healthcare provider, especially if you have a muscular build, a small or large frame, or specific health conditions.

Why is height measured from 5 feet (60 inches) in these formulas?

Devine, Robinson, Miller, and Hamwi were all originally developed using data anchored to a 5-foot (152 cm) baseline weight, with a fixed amount added per inch of height above that baseline. This was simply how the original researchers structured their regression equations from the population data available at the time — it doesn't mean the formulas assume anyone is exactly 5 feet tall.