Ideal Weight Calculator

Ideal Weight Calculator — evidence-based tool to check your ideal weight. Includes formula, tips, and interpretation guide.

An ideal weight calculator estimates a target body weight range for a given height, sex, and body frame using one of several established medical formulas — including the Hamwi formula (widely used in clinical settings), the Devine formula (used for drug dosing calculations), the Robinson formula, or a BMI-derived range (targeting BMI 18.5–24.9). The concept of an "ideal" weight is inherently population-based: all formulas produce averages derived from large reference populations, and individual variation in bone density, muscle mass, and proportions means the formula result may not be appropriate for everyone. BMI Calculator and Daily Calories Calculator are useful companion assessments for a more complete health picture.

Rather than a single number, most clinicians prefer a healthy weight range — typically the weight range corresponding to a BMI of 18.5–24.9 for the given height, adjusted for frame size. Large-framed individuals should target the upper portion of the range; small-framed individuals, the lower portion. The Metropolitan Life Insurance tables of the 1950s and 1960s, which established many "ideal weight" norms, have been largely superseded by more ethnically diverse and contemporary reference populations.

Enter your height in cm or feet/inches.
Select your sex — the formulas differ significantly between male and female.
Optionally estimate your frame size: small (wrist circumference below 15.5 cm for females/17 cm for males), medium, or large (above 16.5 cm/18.5 cm).
The calculator shows the ideal weight range from multiple formulas — compare the results rather than taking any single number as authoritative.
Cross-reference with your current BMI: if within 18.5–24.9, you are likely at a healthy weight regardless of ideal weight formula results.
Use the range as a long-term reference point rather than a precise target — body composition (muscle vs fat) is more important than the number on the scale.

Ideal weight formulas compared

Hamwi (1964): Males: 48 kg + 2.7 kg per inch over 5 ft. Females: 45.5 kg + 2.2 kg per inch over 5 ft. Adjust ±10% for large/small frame.

Devine (1974, used in pharmacology): Males: 50 kg + 2.3 kg per inch over 5 ft. Females: 45.5 kg + 2.3 kg per inch over 5 ft.

Robinson (1983): Males: 52 kg + 1.9 kg per inch over 5 ft. Females: 49 kg + 1.7 kg per inch over 5 ft.

BMI method: Target weight range = height (m)² × 18.5 to height (m)² × 24.9.

Example (5'9" male = 175 cm): Hamwi = 48 + 9×2.7 = 72.3 kg. Devine = 50 + 9×2.3 = 70.7 kg. BMI range = 1.75² × 18.5 to 24.9 = 56.6 to 76.2 kg. The BMI range is the broadest and most permissive; clinical formulas are more specific.

Understanding your ideal weight result

Frame size and weight adjustment

Frame size adjustment: small frame = ideal weight − 10%; medium frame = formula value; large frame = ideal weight + 10%. Wrist circumference is a proxy for frame size: females — small <14 cm, medium 14–16 cm, large >16 cm; males — small <17 cm, medium 17–19 cm, large >19 cm. These formulas were calibrated on early 20th century populations; they produce lower targets than modern reference data suggests is appropriate for some ethnic groups. Focus on body fat percentage and metabolic health markers (blood pressure, blood glucose, cholesterol) alongside weight.

Health tips and best practices

Ideal weight formulas are most useful as a general reference — do not treat the specific number as a medically required target.
For highly muscular individuals, ideal weight formulas significantly underestimate appropriate body weight — a lean 90 kg athlete with 12% body fat is far healthier than any formula would suggest.
If you are currently within the BMI 18.5–24.9 range and metabolically healthy (normal blood pressure, blood glucose, cholesterol), you are likely at an appropriate weight regardless of formula output.
Weight loss beyond the healthy BMI range is associated with increased risk of sarcopenia, osteoporosis, immune dysfunction, and all-cause mortality in older adults — weight goals should incorporate age-specific context.
Children and adolescents should never use adult ideal weight formulas — age- and sex-specific growth charts (WHO or CDC) are the appropriate reference.
For athletes, track body composition percentage rather than ideal weight — a performance-focused goal of 15% body fat for a male athlete is more useful than hitting a specific scale weight.

The Devine formula, published in 1974, was designed for drug dosing calculations in clinical medicine — not as a fitness or aesthetic target, though it is widely used as such.
Average UK adult male weight is approximately 84 kg; female approximately 72 kg (NHS Digital, 2022) — both significantly above ideal weight formula outputs, reflecting current population overweight prevalence.
Research consistently shows that metabolic health markers are more predictive of all-cause mortality than weight alone — a "metabolically healthy obese" individual has better outcomes than a normal-weight individual with metabolic syndrome.
Waist-to-height ratio below 0.5 is consistently associated with lower cardiometabolic risk than any absolute weight target across most ethnic groups studied (Ashwell & Gibson, 2009).

Common mistakes to avoid

Using ideal weight as a precise medical target rather than a broad population reference range — the formulas produce estimates with significant individual variation.
Treating ideal weight for drug dosing (Devine formula) as an aesthetic or fitness target — the Devine formula was specifically designed for pharmacokinetic calculations, not body weight goals.
Applying adult formulas to children or using them without accounting for ethnicity-specific differences in bone density and muscle mass.
Pursuing weight below the healthy BMI range to reach "ideal weight" formula outputs — this is medically inappropriate and the formula outputs for very short individuals in particular can be unrealistically low.

Ideal weight formulas are statistical tools based on historical population data and are for reference purposes only. They do not constitute medical advice, diagnosis, or treatment guidance. Children and adolescents should be assessed using age- and sex-appropriate growth reference charts (WHO or CDC). For clinical weight management, drug dosing, or eating disorder recovery, consult a qualified physician or registered dietitian. This calculator does not account for individual variation in body composition, ethnicity, age, or health status.