Ideal Weight Calculator
Calculate your ideal weight range using four medical formulas: Devine, Robinson, Miller and Hamwi. Adjusted for height, gender and frame size
Medium frame (wrist circumference 15-18cm or 6-7in)
Ideal Weight Range
Target: 70.0 kg
Height: 175.0 cm
Formula Comparison
📊 Frame Size Adjustment
Medium frame: no adjustment needed
Without adjustment:
68.7 – 72.0 kg
📏 How to Measure Frame Size
- 1. Stretch one arm straight out, bend the elbow 90°
- 2. Place fingers of other hand across the inner wrist bone
- 3. Measure the distance between bones
- 4. Compare to: Small <15cm, Medium 15-18cm, Large >18cm
💡 Important
- • These are estimates based on population data
- • Muscle weighs more than fat; athletes may be above range
- • Ideal weight depends on fitness goals and personal health
- • Body composition matters more than the number on the scale
- • Consult a healthcare provider for personalized guidance
How the Four Formulas Differ
The calculator runs four classic formulas: Devine (1974, originally developed for medication dosing), Robinson (1983), Miller (1983), and Hamwi (1964, used for diabetes care). All take a base weight at 60 inches (5ft) and add a set amount of weight per inch above that. The Devine formula is the strictest, Hamwi is the most generous for taller men, and Robinson and Miller sit in the middle.
Because each formula uses slightly different coefficients, you get a range rather than a single number. For a 175cm man, Devine gives 71.5kg, Robinson 70.4kg, Miller 71.7kg, Hamwi 76.5kg. The calculator shows you all four, plus a min-max range and an average, then adjusts for your frame size by adding or subtracting roughly 5kg for large or small frames.
NHS Healthy BMI Range vs Ideal Weight Formulas
| Height | NHS BMI 18.5-24.9 | Devine (women) | Devine (men) |
|---|---|---|---|
| 155cm (5'1") | 44-60kg | 47.6kg | 52.1kg |
| 165cm (5'5") | 50-68kg | 56.7kg | 61.2kg |
| 175cm (5'9") | 57-76kg | 65.8kg | 71.5kg |
| 185cm (6'1") | 63-85kg | 75.0kg | 80.6kg |
Why Ideal Weight Is a Range, Not a Number
The whole concept of one ideal weight for a given height is medically out of date. Body composition matters more than the number on the scale. A muscular 80kg woman at 168cm is healthier than a 60kg woman of the same height with low muscle mass and high visceral fat, even though the formulas would call the lighter weight more ideal. The NHS uses the BMI healthy range of 18.5 to 24.9 as a population guideline, not a personal target.
Better questions than what should I weigh include: do my clothes fit how I want them to, is my waist measurement under 94cm (men) or 80cm (women), is my blood pressure healthy, can I do daily activities without breathlessness. The [BMI calculator](/bmi-calculator) and [body fat calculator](/body-fat-calculator) together give a fuller picture than any ideal weight formula on its own.
Frequently Asked Questions
Which formula should I trust most?
For most adults, Robinson and Miller produce the most realistic numbers. Devine tends to read low for tall men. Hamwi reads high. If you want one figure, take the average of all four. If you have a small or large frame (measured at the wrist), adjust the result down or up by about 5kg accordingly. None of these is a medical diagnosis; they are population averages from decades-old studies.
How do I work out my frame size?
Wrap your thumb and middle finger around the opposite wrist. If they overlap easily, you have a small frame. If they just touch, medium. If they do not meet, large. For a more precise reading, measure the wrist circumference: men under 16.5cm is small, 16.5-19cm medium, over 19cm large. Women under 14cm small, 14-16.5cm medium, over 16.5cm large.
Are these formulas suitable for athletes?
Not really. The formulas assume average muscle mass, which is fine for sedentary or lightly active adults but underestimates a healthy weight for athletes, weightlifters, or anyone with significantly above-average lean mass. A rugby player might be 15kg above their formula ideal weight while sitting at 12% body fat and being entirely healthy. Body fat percentage and waist measurement are far more meaningful for athletic populations.
Should I aim for the lowest number from the formulas?
Generally no. The lowest number is usually Devine, originally created for drug dosing not for health goals. Aiming for it can drive disordered eating in some people. The healthy range, particularly the average across all four formulas, is a more sensible target. If you have specific medical reasons for needing a particular weight (joint problems, sleep apnoea, fertility treatment), your GP or consultant can advise on a personalised target.
Related Tools
BMI Calculator
Calculate your Body Mass Index with our free BMI calculator. Supports metric and imperial units with a visual scale showing your healthy weight range.
Body Fat Calculator
Estimate your body fat percentage using the US Navy method. Shows fat mass, lean mass and body fat category with just a tape measure
TDEE Calculator
Calculate your Total Daily Energy Expenditure using the Mifflin-St Jeor equation. Get calorie targets for weight loss, maintenance and gain