Ideal Weight Calculator
Estimate your ideal body weight in pounds using four established medical formulas adjusted for height, gender, and body frame size. Helpful for setting realistic weight-loss or fitness targets.
About this calculator
This calculator implements four widely cited ideal body weight (IBW) formulas, all derived from population studies and designed for adults over 5 feet tall. The Devine formula (1974): males = 50 + 2.3 × (height_in − 60); females = 45.5 + 2.3 × (height_in − 60). The Robinson formula (1983): males = 52 + 1.9 × (height_in − 60); females = 49 + 1.7 × (height_in − 60). The Miller formula (1983): males = 56.2 + 1.41 × (height_in − 60); females = 53.1 + 1.36 × (height_in − 60). The Hamwi formula (1964): males = 48 + 2.7 × (height_in − 60); females = 45.5 + 2.2 × (height_in − 60). Results in kg are converted to lbs and then adjusted ±5% for small or large body frames. No single formula is universally superior; comparing all four gives a realistic target range.
How to use
Example: a male, 70 inches tall, medium frame, using the Robinson formula. Step 1 — inches above 5 ft: 70 − 60 = 10. Step 2 — IBW (kg): 52 + 1.9 × 10 = 52 + 19 = 71 kg. Step 3 — convert to lbs: 71 × 2.205 = 156.6 lbs. Step 4 — frame adjustment: medium frame = × 1.0, so IBW = 157 lbs. For a large frame the result would be 157 × 1.05 ≈ 165 lbs; for a small frame 157 × 0.95 ≈ 149 lbs. Comparing all four formulas typically yields a range of roughly 150–175 lbs for this individual.
Frequently asked questions
Which ideal weight formula is the most accurate for adults?
No single formula is definitively most accurate for all individuals because these equations were derived from different population samples and decades of research. The Devine formula is the most widely used clinically, especially in pharmacology for drug dosing. The Robinson and Miller formulas tend to produce slightly lower estimates and may better reflect leaner body compositions seen in modern fitness research. Using the average of all four formulas gives a broader, more realistic target range rather than a single possibly misleading number.
How does body frame size affect ideal weight and how do I determine my frame size?
Body frame size accounts for differences in bone density and skeletal structure that cause two people of identical height to have different healthy weights. A common field method is the wrist circumference test: for men over 5'5", a wrist under 6.5 in = small frame, 6.5–7.5 in = medium, over 7.5 in = large. This calculator applies a ±5% adjustment to the base IBW — small frame reduces it by 5% and large frame increases it by 5%. Frame size primarily shifts the target, not the formula itself, so the underlying IBW equation remains the same.
Should I use ideal weight as my actual weight loss goal or is there a better target?
Ideal body weight formulas provide a rough clinical benchmark, not a personal prescription. They were originally developed for drug dosing and insurance tables, not individual fitness goals. A better personal target integrates IBW alongside body fat percentage, waist circumference, and how you feel and perform. Many healthy, athletic individuals weigh above their calculated IBW due to muscle mass. Use the IBW range as a starting reference point, and work with a healthcare provider or dietitian to set a goal that accounts for your full body composition picture.