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Ideal Weight Calculator

Finding your healthy weight range requires more than guesswork. This calculator uses six medically-recognized formulas—Devine, Robinson, Miller, Hamwi, Lorentz, and Broca—plus BMI-based ranges to estimate your ideal body weight. Simply enter your sex and height, and compare your current weight against multiple reference standards. Results highlight how closely you align with evidence-based targets.

Last updated:

Creators Małgorzata Koperska, MD
707 people find this calculator helpful

How to Use This Calculator

Enter your sex and height in your preferred units (metric or imperial). The calculator displays your ideal weight according to six different estimation methods, each validated through medical research. Below the formulas, you'll see your healthy weight range based on a BMI between 18.5 and 24.9—the standard range recommended by health organizations worldwide.

Each formula produces a target figure; these vary slightly because they were developed using different population studies. Rather than fixating on a single number, use the range as your practical guide. The calculator also shows how your current weight compares to these estimates.

The Science Behind Ideal Weight Formulas

Six formulas are commonly used in clinical settings and health research. The Devine formula is the most medically validated and is used by physicians to calculate drug dosages. The other formulas represent refinements or alternatives developed over decades of anthropometric research.

Devine (Men): 50.0 kg + 2.3 kg × (inches over 5 feet)

Devine (Women): 45.5 kg + 2.3 kg × (inches over 5 feet)

Robinson (Men): 52.0 kg + 1.9 kg × (inches over 5 feet)

Robinson (Women): 49.0 kg + 1.7 kg × (inches over 5 feet)

Miller (Men): 56.2 kg + 1.41 kg × (inches over 5 feet)

Miller (Women): 53.1 kg + 1.36 kg × (inches over 5 feet)

Hamwi (Men): 48.0 kg + 2.7 kg × (inches over 5 feet)

Hamwi (Women): 45.5 kg + 2.2 kg × (inches over 5 feet)

Lorentz (Men): (Height in cm − 100) − (Height in cm − 150) ÷ 4

Lorentz (Women): (Height in cm − 100) − (Height in cm − 150) ÷ 2

Broca: Height in cm − 100

BMI Range: 18.5 to 24.9 × Height² (in metres)

  • Height — Your height in centimetres or feet/inches
  • Sex — Biological sex, as different formulas use sex-specific constants
  • BMI — Body Mass Index range from 18.5 (underweight threshold) to 24.9 (overweight threshold)

Understanding BMI and Healthy Weight Ranges

Body Mass Index (BMI) is calculated as weight divided by height squared. A BMI between 18.5 and 24.9 is considered a healthy weight range for adults. This calculator converts those BMI boundaries back into weight, giving you a concrete range rather than a single target.

The advantage of BMI-based ranges is their simplicity and universal application. However, they don't distinguish between muscle and fat. Athletes or individuals with high lean body mass may fall above the upper boundary while remaining fit. Conversely, sedentary individuals within the normal range may lack adequate muscle tone.

Use the formula-based targets as reference points and the BMI range as your broader healthy zone. If your current weight sits within the BMI band, you are generally at a healthy weight relative to your height.

Important Caveats When Interpreting Results

Ideal weight estimates have real limitations—avoid treating them as absolute targets.

  1. Muscle Mass Skews Results — These formulas were developed on average populations and don't account for individual variation in muscle density. Someone with substantial muscle mass may weigh more than calculated targets suggest, yet remain fit. Conversely, someone with low muscle tone may reach targets while lacking fitness.
  2. This Calculator Is for Adults Only — Ideal weight formulas depend on adult body proportions. Do not use this tool to estimate healthy weights for children, adolescents, or pregnant women. Consult a paediatrician or obstetrician for guidance in those situations.
  3. Don't Chase a Precise Number — The six formulas sometimes disagree by several kilograms. Rather than obsessing over reaching one specific target, focus on staying within your BMI range. Being at 59 kg or 61 kg matters far less than maintaining overall health and fitness.
  4. Medical Context Matters — These estimates cannot account for medical history, medications, bone structure, or individual metabolic factors. Always discuss significant weight changes with your doctor rather than relying solely on calculator output.

Safe and Realistic Weight Loss

If your current weight exceeds the ideal range, sustainable weight loss occurs at roughly 0.25–0.5 kg per week—translating to 1–2 kg monthly. This pace minimises muscle loss, preserves metabolic rate, and tends to stick long-term.

Rapid weight loss often rebounds because it relies on unsustainable calorie restriction or dehydration. Instead, combine modest calorie reduction with regular activity. Aim for consistency over speed; changes made gradually become lifestyle habits rather than temporary diets.

Before starting any weight loss programme, consult a healthcare provider, particularly if you have underlying medical conditions or take medications that affect metabolism.

Frequently Asked Questions

What does the Devine formula measure?

The Devine formula estimates ideal body weight based on height and sex. Developed in the 1970s, it remains the most medically validated of the six common methods. Physicians use it to calculate drug dosages for medications like levothyroxine and immunoglobulins. For men, it starts at 50 kg plus 2.3 kg per inch over 5 feet; for women, 45.5 kg plus 2.3 kg per inch over 5 feet. While considered the gold standard, it still represents an average and doesn't account for individual variation in muscle, bone density, or overall body composition.

Why do different formulas give different results?

Each formula was developed using different population samples and research objectives. The Robinson, Miller, and Hamwi formulas represent attempts to refine or adjust the original Devine formula for specific groups. Lorentz and Broca use simpler height-only calculations. Differences typically range from a few kilograms across an individual's estimate. Rather than treating one formula as 'correct,' use them collectively: if most methods cluster in a 5 kg range, that's your realistic target band.

Is BMI a better indicator than formula-based weight?

BMI and formula-based estimates serve different purposes. Formula-based methods give a single target weight; BMI provides a range (18.5–24.9) that accounts for natural variation. BMI is simpler and more widely used clinically, but it ignores muscle-to-fat ratio. An athlete may exceed the BMI upper limit due to muscle. A sedentary person may fall within the range despite poor fitness. Ideally, use both: formula-based targets as waypoints and BMI as a broader guardrail.

Can I use this calculator if I'm pregnant?

No. Pregnancy weight gain follows entirely different guidelines and varies based on pre-pregnancy weight, health status, and individual factors. Use a dedicated pregnancy weight gain calculator and consult your obstetrician for personalised recommendations. Weight loss or maintenance strategies during pregnancy can be harmful to both mother and fetus.

How quickly should I aim to lose weight?

Health professionals recommend losing 0.25–0.5 kg per week, or roughly 1–2 kg per month. Faster loss often comes from water and muscle rather than fat, and rapid dieting tends to fail long-term. Sustainable weight loss combines modest calorie reduction (500 calories per day creates roughly 0.5 kg weekly loss) with regular physical activity. The slower your approach, the more likely the results will last and the less metabolic stress you'll experience.

What if my ideal weight range seems too high or too low for me?

Ideal weight estimates are population averages and may not fit your unique physiology. If you feel the estimate is misaligned with your fitness or health markers, discuss it with your doctor. Factors like bone density, muscle mass, age-related metabolism, and medical conditions can justify weights outside the calculated range. Your doctor can assess whether your current weight is appropriate for you individually, independent of what a calculator suggests.

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