Ideal Weight Calculator

How it works

Each formula starts with a base weight at 5 feet (60 inches) and adds a set amount for each inch above that:

We show the lowest and highest result as your formula range. Separately, the healthy BMI range is the weight that gives a BMI of 18.5 to 24.9 at your height.

Heights under 5 feet

The original formulas were written for people 5 feet and taller. For shorter heights, a common convention — which we follow — is to subtract the same per-inch amount for each inch below 5 feet. This is an extrapolation the formulas were not designed for, so results under 5 feet are less reliable; the BMI-based range may be a better guide.

Where these formulas come from

Devine's formula was published in 1974 to help dose the antibiotic gentamicin, not to define an attractive or healthy weight; Robinson and Miller later refined it with population data. Hamwi's formula came from diabetes diet planning in 1964. Pai and Paloucek (2000) review this history. They remain useful reference points, but none accounts for frame size, muscle or age.

A healthier way to think about "ideal"

Health organizations focus less on a single ideal weight and more on a healthy range combined with good habits and health markers such as blood pressure, blood sugar, cholesterol, fitness and waist size. For many people with a higher weight, losing even 5–10% of body weight improves these markers meaningfully, even if they never reach a formula's "ideal" number.

Ideal weight in medicine

Clinicians still use ideal body weight — usually the Devine formula — to calculate doses of some medicines (for example certain antibiotics) and to set safe breathing volumes on ventilators, because lung size relates to height rather than weight. Those clinical uses are why the formulas remain in textbooks.

Worked examples

Example 1: Man, 5′10″

10 inches over 5 ft. Devine = 50 + 23 = 73 kg (161 lb); Robinson 156 lb; Miller 155 lb; Hamwi 165 lb. Formula range 155–165 lb; healthy BMI range 129–174 lb.

Example 2: Woman, 5′4″

4 inches over. Devine 121 lb; Robinson 123 lb; Miller 129 lb; Hamwi 120 lb. Range 120–129 lb; BMI range 108–145 lb.

Example 3: Woman, 4′10″ (under 5 ft)

2 inches below 5 ft, so amounts are subtracted: Devine = 45.5 − 4.6 = 40.9 kg (90 lb); Robinson 101 lb; Miller 111 lb; Hamwi 91 lb. Range 90–111 lb; BMI range 89–119 lb. Treat with caution.

Limitations

• Formulas ignore muscle mass, frame size, age and ethnicity.
• Originally designed for drug dosing and diet planning, not as personal targets.
• Below 5 feet the formulas are extrapolated.

Who should not rely on this calculator

Not for children or teens, pregnancy, very muscular people, or anyone with an eating disorder or history of one. A healthy weight for you is best discussed with a healthcare professional.