Ideal Weight Calculator
Calculate your ideal weight using Robinson, Miller, Devine and Hamwi formulas. See your healthy BMI range.
By Konstantin Iakovlev · Founder, Calks.uk
Last updated: · Verified against HMRC and GOV.UK 2026/27 rates
Average Ideal Weight
70.0 kg
Healthy BMI range: 56.7 – 76.3 kg
Robinson
68.9 kg
Miller
68.7 kg
Devine
70.5 kg
Hamwi
72.0 kg
Disclaimer
This calculator is provided for informational purposes only and should not be considered as financial or tax advice. All calculations are performed locally in your browser — no personal data is collected or sent to our servers. Rates and thresholds are sourced from HMRC and GOV.UK and are updated for the current tax year. Always verify results with HMRC or consult a qualified professional before making financial decisions.
How It Works
This calculator estimates your ideal weight range using several established formulas. The BMI method defines a healthy range as a BMI between 18.5 and 24.9. The Devine formula (1974) and Robinson formula (1983) each use height to produce a single ideal weight figure, originally developed for drug-dosing calculations.
For a given height, the calculator shows the healthy BMI weight range alongside the Devine and Robinson estimates. No single number is definitive — body composition, frame size and ethnicity all influence what is healthy for you. The NHS uses BMI as a screening tool but acknowledges its limitations for muscular builds.
Enter your height and sex to see all three estimates. The results give a reasonable target range rather than a single figure. If you are concerned about your weight, your GP can take body composition, waist circumference and medical history into account for a fuller assessment.
BMI vs Ideal Body Weight — different concepts. BMI (Body Mass Index) = weight (kg) ÷ height² (m²). NHS healthy range 18.5-24.9. Ideal Body Weight (IBW) formulas predict a specific target weight based on height + sex + frame. Multiple formulas exist: Robinson (1983), Miller (1983), Devine (1974), Hamwi (1964) — give similar results within ±5kg. Devine formula: Men IBW = 50 + 2.3 × (height in inches − 60); Women IBW = 45.5 + 2.3 × (height in inches − 60).
Ideal weight ranges by height. Sample ranges (Devine adjusted ±10%): Height 5'0" (152cm) — women 47-58kg, men 47-58kg. Height 5'4" (163cm) — women 56-69kg, men 56-69kg. Height 5'8" (173cm) — women 64-79kg, men 65-80kg. Height 6'0" (183cm) — women 74-90kg, men 75-92kg. Height 6'4" (193cm) — women 84-103kg, men 86-105kg. NHS recommends BMI-based healthy weight ranges, which differ slightly: 1.75m height = 56.7-76.6kg BMI healthy range.
Frame size — small, medium, large. Wrist circumference method: measure dominant wrist with tape. Men <17cm = small; 17-19cm = medium; >19cm = large. Women <15cm = small; 15-17cm = medium; >17cm = large. Adjustments: subtract 10% from IBW for small frame; add 10% for large frame. Or elbow breadth (more precise but harder to measure). Population variation: ethnic differences exist — Asian populations typically lower IBW thresholds, Pacific Islander populations higher.
Why 'ideal weight' is misleading for muscular people. A muscular athlete at IBW formulas may appear underweight on scale but have low body fat. Rugby player 100kg at 1.85m = BMI 29.2 (overweight) but might be 12% body fat (elite athlete). Conversely 'skinny fat' — within IBW but high body fat percentage. Better measures: body fat % (men healthy 8-19%, women 21-32%), waist circumference (under 94cm men, 80cm women), waist-to-height ratio under 0.5.
Setting realistic weight goals. Safe weight loss rate: 0.5-1 kg/week (NHS guideline). Faster usually unsustainable + muscle loss. Calorie deficit: 500-1,000 kcal/day under TDEE = 0.5-1 kg/week. Combine with: 1.6-2.2g protein/kg bodyweight to preserve muscle; strength training 2-3×/week; cardio for energy expenditure. Avoid: very low calorie (<1,200/day women, <1,500 men) — metabolic adaptation, muscle loss, plateau. Track progress weekly (morning, after toilet, before food). Plateau after 3-4 months is normal — body resets, take a 2-week 'diet break' at maintenance calories before continuing.
Example: Male, 178 cm (5'10")
- BMI healthy range (18.5–24.9): 58.6–78.9 kg
- Devine formula: 73.5 kg
- Robinson formula: 72.6 kg
- Suggested target range: 68–79 kg
Frequently Asked Questions
- What does the Ideal Weight Calculator do?
- Calculate your ideal weight using Robinson, Miller, Devine and Hamwi formulas. See your healthy BMI range.
- Why are there different ideal weight formulas?
- Common ones — Devine (1974): male 50kg + 2.3kg per inch over 5ft; female 45.5kg + 2.3kg per inch over 5ft. Robinson (1983): similar but adjusted. Miller (1983): male 56.2kg + 1.41kg per inch; female 53.1kg + 1.36kg per inch. Hamwi (1964): less accurate. BMI-based: weight × 22 (mid-range of healthy BMI 18.5-24.9). None is universally accurate — they were derived for medication dosing, not health goals. Use as a rough range, not a strict target.
- Is ideal weight even a useful concept?
- Less so than people think. 'Healthy weight' is a range, not a single number. Two people of the same height and age can both be healthy at weights differing by 5-10kg if one is muscular and one is lean. Body composition (% muscle vs fat) matters more than total weight. Waist circumference (<94cm men, <80cm women) and waist-to-height ratio (<0.5) are better health indicators than BMI or 'ideal weight' formulas.
- What if I'm above 'ideal weight' but feel healthy?
- If your blood pressure, cholesterol, blood sugar, and waist circumference are normal, you may be metabolically healthy at higher BMI — the 'overweight paradox'. However, even metabolically healthy higher weight increases joint pain, sleep apnoea, and certain cancers long-term. Focus on health markers, not the scale: can you climb stairs without breathing hard? Walk briskly for 30 min? Have energy through the day? These matter more than hitting a 'formula' weight.