Ideal Weight Calculator

Most people have, at some point, tried to lose weight—or know someone who has—often driven by an “ideal” body weight promoted through social media, television, or magazines. In reality, however, the concept of Ideal Body Weight (IBW) was devised not for aesthetics but to guide medical dosing: it more accurately predicts how the body metabolizes certain drugs than total body weight. Today, IBW is also used in sports that classify competitors by weight.

Important: IBW (and other measures such as Body Mass Index, or BMI) neither account for differences in body fat versus muscle nor reflect an individual’s overall health. Many athletes, for example, may exceed their “ideal” weight yet be perfectly healthy. Rather than chasing a specific number on the scale, it’s far more important to adopt lifelong habits—balanced nutrition, regular exercise, adequate sleep, and stress management—that support overall well-being.

Major Factors That Influence “Ideal” Weight

Although no single formula can prescribe your perfect weight, IBW calculators generally adjust for four key variables:

1. Age
   After adolescence, height—and therefore IBW—remains relatively stable. By about age 70, most people lose 1.5–2 inches of height, along with some lean muscle mass, which can shift body composition toward higher fat percentages.
2. Gender
   On average, men carry more muscle and have denser bones than women, making their ideal weights roughly 10–20 percent higher, even at the same height.
3. Height
   Taller individuals naturally carry more muscle and fat, so IBW formulas typically start with a base weight at 5 feet and then add a fixed amount per additional inch.
4. Body Frame Size
   Measured by the circumference of the wrist relative to height, frame size is categorized as small, medium, or large. Larger-boned individuals tend to weigh more than smaller-boned individuals of the same height. Women
   • Under 5′2″:
     • Small: wrist < 5.5″
     • Medium: 5.5–5.75″
     • Large: > 5.75″
   • 5′2″–5′5″:
     • Small: < 6″
     • Medium: 6–6.25″
     • Large: > 6.25″
   • Over 5′5″:
     • Small: < 6.25″
     • Medium: 6.25–6.5″
     • Large: > 6.5″
   Men
   • Over 5′5″:
     • Small: 5.5–6.5″
     • Medium: 6.5–7.5″
     • Large: > 7.5″

Common IBW Formulas

All formulas below calculate a base weight for a 5 foot (60″) person, then add a fixed weight per each inch above that height. Although originally developed to guide drug dosages, these formulas are now used more broadly:

Example: A 5′10″ male by the Devine formula:

50.0 kg + (2.3 kg × 10 inches) = 73 kg (≈ 161 lbs).

Using BMI as a Reference

The World Health Organization defines a “healthy” BMI as 18.5–25 for adults (18 years and older). You can calculate the weight range for any height:

BMI = weight (kg) ÷ [height (m)]²

For children and teens (ages 2–20), the Centers for Disease Control and Prevention recommend maintaining a BMI between the 5th and 85th percentiles for age and gender. Consult CDC growth charts to determine the corresponding weight range.

Limitations of IBW and BMI

• Body Composition: Neither method distinguishes muscle from fat.
• Activity Level & Athletic Build: Highly active or muscular people may fall outside “ideal” ranges despite excellent health.
• Age-Related Changes: Muscle loss and fat redistribution with age can skew results.
• Health Conditions: Certain illnesses or medications can affect weight independently of height and frame size.

Bottom Line: Treat IBW and BMI as guidelines, not strict targets. Focus on healthy behaviors—balanced nutrition, strength training to maintain muscle mass, regular cardiovascular exercise, and sufficient rest—to support overall health and well-being, regardless of the number on the scale.