Ideal Weight Calculator
This calculator estimates an ideal body weight for your height using two widely cited medical formulas: Devine (1974), which is still used for drug dosing, and Robinson (1983), a later refinement. It also shows the weight range that corresponds to a normal BMI of 18.5 to 24.9, which many clinicians consider the more meaningful target.
- Healthy BMI range (18.5–24.9)
- 59.9 kg – 80.7 kg
- Devine formula
- 75 kg
- Robinson formula
- 72.6 kg
An "ideal" weight is a statistical estimate, not a personal prescription. Frame, muscle mass, age, and ethnicity all shift what is healthy for an individual. Use the range as orientation, and rely on how you feel, your fitness, and medical advice for real decisions.
How it's calculated
Devine: 50 kg (men) / 45.5 kg (women) + 2.3 kg per inch over 5 ft
Robinson uses 52 kg + 1.9 kg/inch for men and 49 kg + 1.7 kg/inch for women. The healthy BMI range is computed as 18.5 × height² to 24.9 × height² with height in meters.
Worked example
A 180 cm (5'11") man: Devine gives 50 + 2.3 × 10.9 ≈ 75 kg, Robinson gives 52 + 1.9 × 10.9 ≈ 72.7 kg, and the healthy BMI range is 60 to 80.7 kg. All three agree that mid-70s kg is a reasonable target.
Frequently asked questions
›Why do the formulas give different answers?
Each was derived from different population data decades apart. They are best read together as a range rather than as one exact number.
›Which formula should I trust?
For most purposes the healthy BMI range is the most useful guide, since it is what health organizations use. The Devine formula remains standard in medicine for calculating drug doses.
›Does age affect ideal weight?
Somewhat. Research suggests slightly higher BMIs are not harmful in older adults, and may even be protective. These formulas do not adjust for age.
›I'm outside the range. Should I worry?
Not automatically. Muscular people commonly exceed formula weights, and naturally slim people may sit below them. Discuss significant concerns with a healthcare professional rather than dieting to a formula.
Related tools
BMI Calculator
Calculate your Body Mass Index (BMI) from height and weight in metric or imperial units, and see which BMI category you fall into.
Calorie & BMR Calculator
Calculate your Basal Metabolic Rate (BMR) and daily calorie needs based on age, sex, height, weight, and activity level.
Body Fat Calculator
Estimate your body fat percentage from height, neck, waist, and hip measurements using the US Navy circumference method, with fitness categories.