How to use the ideal weight calculator
- Choose Metric (cm, kg) or US units (ft, in, lb).
- Pick your sex. Each formula has a separate version for men and women.
- Enter your height.
- Read the range the four formulas give, the average, and the healthy BMI range for the same height.
How ideal weight is calculated
All four formulas start with a fixed weight for someone exactly 5 feet (60 inches) tall, then add a set amount for every inch above that:
Hamwi's rule was first written in pounds (106 lb plus 6 lb per inch for men, 100 lb plus 5 lb per inch for women), and the kilogram version above is the one in common use. Devine's formula was designed to help dose medicines, not to set a goal weight, yet it became the most widely quoted of the four. Robinson and Miller later refitted the same idea to life-insurance height and weight data. The healthy BMI range is simply 18.5 × height² to 24.9 × height², with height in meters.
Worked example
These are the calculator's defaults: a man, 175 cm tall.
- Height in inches: 175 ÷ 2.54 = 68.90 in, which is 8.90 inches over 5 feet
- Robinson: 52 + 1.9 × 8.90 = 68.9 kg
- Miller: 56.2 + 1.41 × 8.90 = 68.7 kg
- Devine: 50 + 2.3 × 8.90 = 70.5 kg
- Hamwi: 48 + 2.7 × 8.90 = 72.0 kg
- Range of the four: 68.7 – 72.0 kg, with an average of 70.0 kg
The healthy BMI range at 1.75 m is 18.5 × 3.0625 = 56.7 kg up to 24.9 × 3.0625 = 76.3 kg. All four formulas land near the middle of it.
Formulas vs. the BMI range
The formulas each give one number, which makes "ideal" sound more exact than it is. The BMI range is wider and better supported by health research: at 175 cm it spans almost 20 kg. A muscular person can sit well above every formula and still be healthy. A small-framed person can be healthy below them all.
| Height | Devine (men) | Devine (women) | Healthy BMI range |
|---|---|---|---|
| 5 ft 2 in (157.5 cm) | 54.6 kg | 50.1 kg | 45.9 – 61.8 kg |
| 5 ft 6 in (167.6 cm) | 63.8 kg | 59.3 kg | 52.0 – 70.0 kg |
| 5 ft 10 in (177.8 cm) | 73.0 kg | 68.5 kg | 58.5 – 78.7 kg |
| 6 ft 2 in (188.0 cm) | 82.2 kg | 77.7 kg | 65.4 – 88.0 kg |
The formulas were not designed for people under 5 feet. Below that height the calculator subtracts the per-inch amount, which gives a rough figure at best. The formulas also ignore age, muscle and frame size, and none of them apply to children or to pregnancy. If you are setting a weight goal for health reasons, a doctor or dietitian can help you choose one that fits you.
Frequently asked questions
Which ideal weight formula is the most accurate?
None of them is accurate for an individual, because none measures body composition. Devine is the one most used in hospitals, mainly for drug dosing. Robinson and Miller tend to give lower numbers for tall people. The healthy BMI range is a better guide to a sensible weight.
Why does my ideal weight differ between the formulas?
Each was fitted to different data at a different time, so the starting weights and per-inch amounts differ. At average heights they agree within a few kilograms. The gap widens for very tall or short people.
Does the calculator account for muscle or frame size?
No. The formulas use only height and sex. If you carry a lot of muscle, your healthy weight may be above every formula. The body fat calculator gives a better picture of your composition.
Should I try to reach my ideal weight exactly?
No. Treat the numbers as a ballpark. Staying within the healthy BMI range, being active and eating well matter more than hitting a single figure. Talk to your doctor before starting a weight-loss plan.
Related calculators
- Healthy Weight Calculator — The healthy weight range for your height, where your weight sits, and how far you are from the range.
- BMI Calculator — Your body mass index, weight category and healthy weight range, in metric or US units.
- Body Fat Calculator — Estimate your body fat percentage with the U.S. Navy tape method and compare it with a BMI-based estimate.
- Lean Body Mass Calculator — Lean body mass from your height and weight with the Boer, James and Hume formulas, plus the body fat each implies.
Results are estimates for general information and are not medical advice. Talk to a doctor or other qualified professional about your health. See our disclaimer.