Free Healthy Weight Tool

Ideal Weight Calculator

What is an ideal weight? Ideal body weight (IBW) is an estimate of the weight range associated with good health for a given height and sex. There is no single universally correct answer — the four major medical formulas (Hamwi, Devine, Robinson, and Miller) were developed for clinical drug-dosing purposes, not aesthetic goals. They provide a practical starting range, but factors like muscle mass, frame size, age, and ethnicity all affect what weight is optimal for any individual. Use the range as a guide, not an absolute target.

Ideal Weight Engine

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Biological Sex

Height

Age (optional)

Frame Size (optional)

Understanding Ideal Weight

Why There Is No Single Ideal Weight

The four formulas used here were developed in the 1960s–1980s primarily for medication dosing in clinical settings — not for defining healthy aesthetics. They do not account for muscle mass (a lean athlete may weigh well above the formula range and be perfectly healthy), frame size, ethnicity, age-related body composition shifts, or fitness level. A better goal than matching a single formula number is maintaining a healthy body fat percentage and lean mass for your age and sex.

Beyond the Scale — Body Composition

Two people at the exact same weight and height can look completely different because of body composition. A 70 kg person with 15% body fat has roughly 10.5 kg of fat and 59.5 kg of lean mass — very different from a 70 kg person at 30% body fat (21 kg fat / 49 kg lean). Scale weight is a rough proxy for health. Body fat percentage, waist-to-height ratio, and lean mass index give a far more complete picture of metabolic health and physical fitness.

Focus on Nutrition, Not Just Weight

Reaching your ideal weight is 80% nutrition. The FitScanned app uses AI photo scanning to log meals instantly — making it easy to stay consistent without tedious calorie counting.

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Quick Facts

✓Uses 4 medical formulas averaged
✓BMI healthy range: 18.5 – 24.9 kg/m²
✓Frame size modifier: ±10%
✓For adults over 60, slightly higher ranges may apply
✓Scale weight is not the only health metric

Common Questions

What is the most accurate ideal weight formula?↓

No single formula is universally most accurate — each was developed for different clinical populations. The Devine formula is most widely used in medicine (particularly for drug dosing), while averaging all four gives the broadest and most representative range for the general population.

Is ideal weight the same as a healthy BMI weight?↓

Not exactly. The formula-based ideal weight often falls within the BMI 18.5–24.9 range, but not always — the two methods use different reference data. The BMI healthy range is generally broader and accounts only for height, while ideal weight formulas also factor in sex.

Can I be overweight but still healthy?↓

Yes. Research shows that fitness level is a stronger predictor of mortality than body weight alone. An "overweight" person (BMI 25–29.9) who exercises regularly and has a healthy metabolic profile can have better health outcomes than a "normal weight" sedentary individual. Weight is one piece of the health picture.

Does muscle weigh more than fat?↓

A kilogram of muscle weighs the same as a kilogram of fat — but muscle is denser and takes up about 20% less volume. This is why two people can weigh the same but look very different. Athletes often weigh above ideal weight formula ranges because muscle is heavier than fat for the same body size.

How do I know if I have a small, medium, or large frame?↓

A common clinical method: wrap your thumb and middle finger around the smallest part of your wrist. If they overlap, you have a small frame; if they just touch, medium; if they do not touch, large. Alternatively, wrist circumference charts based on height provide a more standardised estimate.