Ideal Weight Calculator
Estimate ideal body weight from height and gender using the widely used Devine formula.
How to use the Ideal Weight Calculator
- Choose Metric (cm) or Imperial (ft/in), then select male or female.
- Enter your height.
- Read the ideal weight estimate in both kilograms and pounds, and treat it as a reference point rather than a target.
About the Ideal Weight Calculator
This calculator estimates ideal body weight (IBW) using the Devine formula, one of the most widely cited formulas of its kind, originally developed for calculating medication dosages and still commonly referenced today. It starts from a base weight for a 5-foot-tall adult and adds a fixed amount for every inch of height above that: 2.3 kg per inch for men (starting at 50 kg) and 2.3 kg per inch for women (starting at 45.5 kg).
Enter your height in metric (centimeters) or imperial (feet and inches) and select your gender, and the calculator converts your height to inches internally, applies the formula, and shows the result in both kilograms and pounds. Because the formula is calibrated for adult heights of 5 feet and above, heights below that don't produce a meaningful result.
Worked example
Example: a man who is 5 ft 10 in (70 inches) tall has an estimated ideal weight of 50 + 2.3 × (70 − 60) = 73 kg, or about 160.9 lb.
The Devine formula in metric
The formula is written in inches, but it converts neatly to centimeters: 2.3 kg per inch is about 0.91 kg per centimeter, and 5 feet is 152.4 cm. So ideal body weight is about 50 + 0.91 × (height in cm − 152.4) kg for men, and 45.5 + 0.91 × (height in cm − 152.4) kg for women. This is the same calculation used for 'predicted body weight' in hospital settings, such as setting ventilator volumes and dosing certain drugs, which is the main reason the formula is still in use.
How the other formulas compare
Several formulas use the same structure — a base weight at 5 feet plus a fixed amount per inch — with different constants. For a man 5 ft 10 in (70 inches) tall, they give:
- Devine (1974): 50 kg + 2.3 kg per inch = 73 kg.
- Robinson (1983): 52 kg + 1.9 kg per inch = 71 kg.
- Miller (1983): 56.2 kg + 1.41 kg per inch = 70.3 kg.
- Hamwi (1964): 48 kg + 2.7 kg per inch = 75 kg.
- The spread of about 5 kg is a good reminder that 'ideal weight' is really a range.
Putting the number in context
For most adult heights, the Devine result corresponds to a BMI of about 20–23, comfortably inside the healthy 18.5–24.9 band; at 70 inches, 73 kg is a BMI of about 23.1. The formulas were built from limited data and don't account for frame size, muscle, or age, and they're less reliable for people under 5 feet or much taller than average. Use the result as a reference point alongside BMI, waist measurement, and advice from a health professional.
Frequently asked questions
- Is the Devine formula the only way to estimate ideal weight?
- No — it's one of several formulas used in clinical practice (others include the Robinson, Miller, and Hamwi formulas), and different formulas can give slightly different results for the same height. Devine is widely used partly because it's the formula most commonly referenced for calculating medication dosages, but it's not the single 'correct' answer.
- How is this different from the BMI calculator's healthy weight range?
- This calculator gives a single point estimate based only on height and gender, while the BMI calculator shows a healthy weight range (based on the WHO's 18.5–24.9 BMI band) that already accounts for the fact that a healthy weight isn't just one number. Both are simplified formulas, and neither factors in muscle mass, body frame size, or individual health.
- Why does the formula use different starting weights for men and women?
- The formula was derived from population data reflecting typical differences in body composition between men and women at a 5-foot reference height, which is why the male starting weight (50 kg) is higher than the female starting weight (45.5 kg), even though both add the same amount per inch above that.
- Should I use this number as a weight-loss or weight-gain target?
- Treat it as a general reference point, not a personal target. It doesn't account for muscle mass, bone structure, age, or overall health, so a muscular or larger-framed person may be perfectly healthy well above this number. For an individualized target, talk to a doctor or registered dietitian.