Ideal Weight Calculator for Your Height
Ideal weight formulas give a rough single number based on your height and sex. This calculator shows four of them side by side — Devine, Robinson, Hamwi and the BMI-healthy range — because they disagree by several kilograms. The BMI range is usually the most useful of the four, since it gives you a span rather than a point estimate.
What is ideal weight calculator?
The idea of a single ideal weight comes from insurance actuarial tables and clinical dosing formulas, not from any study of what makes people feel or perform their best.
The Devine formula, published in 1974, was actually designed to calculate drug dosages, not to advise people on weight. It became popular simply because it was easy to remember.
A healthier framing is a range. Body weight naturally fluctuates 1 to 2 kg day to day from food, fluid and glycogen, so any single-number target invites unnecessary precision.
How ideal weight is estimated
All three classic formulas start from a base weight for a 5-foot person and add a fixed amount per inch of height above that. The BMI approach is different: it works backwards from the healthy BMI band of 18.5 to 24.9 and converts it into a weight range for your height.
Devine: Men 50 kg + 2.3 kg per inch over 5 ft | Women 45.5 kg + 2.3 kg
Robinson: Men 52 kg + 1.9 kg per inch over 5 ft | Women 49 kg + 1.9 kg
Hamwi: Men 48 kg + 2.7 kg per inch over 5 ft | Women 45 kg + 2.7 kg
BMI range: 18.5 × height(m)² to 24.9 × height(m)²Source: Devine (1974), Robinson (1983), Hamwi (1964); WHO BMI classification.
How to use this calculator
- Enter your height and sex.
- Compare the four estimates — if they cluster tightly, you have a reasonable target zone.
- Use the BMI-healthy range as your practical band rather than a single number.
- Adjust downward for a small frame and upward for a large frame or high muscle mass.
Frequently asked questions
Is there really one ideal weight?
No. These formulas predate modern understanding of body composition and ignore frame size, muscle mass and age. Treat the output as a conversational starting point, not a goal to chase.
Why do the formulas disagree?
They were built for different purposes from different population samples across different decades. Devine was designed for drug dosing, which is why it sits slightly lower than the others.
Does age change my ideal weight?
Slightly. Body composition shifts with age even at a stable weight, and a BMI somewhat higher than the young-adult optimum is associated with better outcomes in older adults. These formulas do not account for age.
Should athletes use this?
Muscular people will usually weigh well above the formula estimate while being perfectly healthy. Body fat percentage is a far better guide for them.
Related calculators
- BMI Calculator — Free BMI calculator for metric and imperial units. Instantly see your body mass index, which weight category you fall into, and your healthy weight range.
- Body Fat Calculator — Estimate your body fat percentage from waist, neck and hip measurements using the US Navy circumference method. Works in metric and imperial.
- Calorie Calculator — Free calorie calculator using the Mifflin-St Jeor equation. See how many calories you should eat to maintain, lose or gain weight, plus your BMR.
These figures are estimates from population formulas, not medical advice. Individual needs vary. If you are pregnant, managing a medical condition, or under 18, talk to a doctor before changing your diet.