Ideal Body Weight Calculator — 4 Formulas Compared Free

What should you weigh? There is no single answer — it depends on your height, gender, frame size, and muscle mass. Our Ideal Body Weight Calculator uses four established medical formulas to give you a range, which is far more useful than a single number.

What Is Ideal Body Weight?

Ideal body weight (IBW) formulas were originally developed for drug dosing calculations, but they have become popular as health reference points. The four most widely used formulas — Devine, Robinson, Miller, and Hamwi — each use height and gender to estimate an ideal weight. They produce slightly different results, giving you a practical range.

How to Use Our Calculator

1. Select your gender and enter your height.
2. The calculator shows results from all four formulas.
3. A combined range and average are displayed for quick reference.
4. Use the range as a guide, not an absolute target.

Why Check Ideal Body Weight?

• Goal setting: A research-backed range is a better starting point than an arbitrary number.
• Medical context: Ideal body weight is used in clinical settings for medication dosing, ventilator settings, and nutritional assessments.
• Reality check: Some goal weights are unrealistic or unhealthy. The IBW range provides a sanity check.
• Multiple perspectives: Seeing four different estimates highlights that "ideal" is a range, not a single number.

Common Use Cases

People setting a weight loss goal use IBW calculators to determine a realistic target. Aiming for the middle of the range is reasonable for most people, while athletes or those with more muscle mass may healthily sit above the range.

Healthcare providers use IBW in clinical calculations — for example, tidal volume in mechanical ventilation is based on ideal body weight, not actual weight.

Tips and Best Practices

• These formulas do not account for muscle mass. A muscular person will naturally weigh more than the calculated "ideal" and that is perfectly healthy.
• Body fat percentage and waist circumference are better health indicators than weight alone.
• The formulas were developed primarily from data on Western populations and may be less accurate for other body types.

Ready to try it? Use our free Ideal Body Weight Calculator now — no signup required, works entirely in your browser.

Frequently Asked Questions

Which ideal body weight formula is most accurate?

No single formula is definitive. The Devine formula is most commonly used in clinical settings, but looking at the range from all four formulas (Devine, Robinson, Miller, Hamwi) gives a more realistic target range.

Should I aim for my ideal body weight?

Ideal body weight formulas provide a reference range, not a mandate. Your optimal weight depends on muscle mass, frame size, age, and overall health markers. A body fat percentage in the healthy range may be more meaningful than a specific weight number.

Why do the four formulas give different results?

Each formula was developed from different population data and uses slightly different assumptions about the relationship between height and healthy weight. The variation highlights that there is no single "correct" weight for a given height.