Ideal Body Weight Calculator
The Devine formula estimates ideal weight from height alone: 50 kg (men) or 45.5 kg (women) at 5 feet tall, plus 2.3 kg for every inch above that. At 175 cm, that's about 70.5 kg for a man.
Ideal weight
70.5 kg
In pounds
155 lb
Show the math
- 1
Convert height to inches
175 cm ÷ 2.54 = 68.9 in
The Devine formula was developed in inches and feet.
= 68.9 in
Read the steps as text
- Convert height to inches. 175 cm ÷ 2.54 = 68.9 in The Devine formula was developed in inches and feet.
- Find inches over 5 feet. 68.9 − 60 = 8.9 in 5 feet (60 inches) is the formula's baseline height.
- Multiply by 2.3 kg per inch. 8.9 × 2.3 = 20.5 kg
- Add the men's base weight. 50 + 20.5 = 70.5 kg The base is 50 kg at 5 feet tall, 50 kg for men.
Where the Devine formula comes from
The Devine formula was published in 1974, originally to help estimate drug dosages based on body size rather than as a fitness or beauty standard. It's since become one of the most widely used 'ideal weight' formulas in medicine precisely because it's simple: it only needs height and sex.
Like BMI, it doesn't account for muscle mass, frame size, or body composition — a muscular or larger-framed person will naturally sit above the formula's number without that meaning anything is wrong.
How much this should matter to you
Treat this as a rough population-level reference point rather than a personal target. Several similar formulas exist (Robinson, Miller, Hamwi) and they don't all agree exactly, which is itself a sign that no single number captures what's healthy for a specific individual. Body composition, muscle mass and overall health markers matter more than matching a formula from 1974.
Frequently asked questions
- How accurate is an ideal weight formula?
- It's a rough population-level estimate, not personalised medical advice. It doesn't account for muscle mass, frame size or body composition, so treat it as a reference point rather than a target.
- Why does the formula only need height and sex?
- It was designed in 1974 to estimate drug dosing quickly from easily available information, not as a comprehensive health assessment — that simplicity is also its main limitation.
- Is a higher number always better, or worse?
- Neither — being above or below the formula's estimate doesn't by itself indicate a health problem. Muscle mass, body fat percentage and overall fitness are more meaningful indicators.