Ideal body weight formulas calculate a target based on height, sex, and sometimes frame size. The Robinson Formula: men = 52 kg + 1.9 kg per inch over 5 feet; women = 49 kg + 1.7 kg per inch over 5 feet. A 5'10" man has an estimated ideal weight of 71 kg (157 lbs). But four major formulas exist and they vary by 10–20 lbs — the range, not a single number, is what matters.
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What Is an Ideal Weight Calculator?
An ideal weight calculator estimates a healthy target body weight for a given height and sex using one or more clinical formulas. It shows a range — not a single number — because different formulas produce different estimates, and healthy weight genuinely varies by frame size, muscle mass, and body composition.
The concept of "ideal weight" originated in 1950s life insurance actuarial tables, where insurers identified weight ranges associated with lower mortality risk. Several clinical formulas were later developed for medical use (drug dosing, nutritional assessment): the Devine Formula (1974), Robinson Formula (1983), Miller Formula (1983), and Hamwi Formula (1964). Each produces slightly different estimates; together they define a reasonable target range.
Importantly, these formulas use only height and sex — they cannot account for frame size, muscle mass, or body composition. A muscular 5'10" athlete and a sedentary 5'10" person have the same "ideal weight" by these formulas, despite very different health profiles. This is why modern health assessment uses body fat percentage and metabolic markers alongside weight.
The calculator on RoughTools shows all four formula estimates plus the healthy BMI weight range for your height, giving you the full picture of where your weight stands relative to multiple reference points.
How to Use the Ideal Weight Calculator
- Enter your height. In feet and inches or centimeters.
- Select your sex. Formulas differ by biological sex due to average body composition differences.
- Select your frame size (optional). Small, medium, or large frame. Wrist circumference is the most common measurement: for men, wrist ≤6.5" = small frame; 6.5"–7.5" = medium; ≥7.5" = large. For women, wrist ≤5.5" = small; 5.5"–6.5" = medium; ≥6.5" = large.
- Read the results. Ideal weight from four formulas (Robinson, Miller, Hamwi, Devine), the healthy BMI weight range for your height, and a recommended target range that accounts for frame size.
The Four Major Ideal Weight Formulas
Devine Formula (1974, originally for drug dosing):
- Men: 50.0 kg + 2.3 kg per inch over 5 feet
- Women: 45.5 kg + 2.3 kg per inch over 5 feet
Robinson Formula (1983):
- Men: 52.0 kg + 1.9 kg per inch over 5 feet
- Women: 49.0 kg + 1.7 kg per inch over 5 feet
Miller Formula (1983):
- Men: 56.2 kg + 1.41 kg per inch over 5 feet
- Women: 53.1 kg + 1.36 kg per inch over 5 feet
Hamwi Formula (1964, for clinical use):
- Men: 106 lbs + 6 lbs per inch over 5 feet
- Women: 100 lbs + 5 lbs per inch over 5 feet
Comparison for a 5'8" (68") man (8 inches over 5 feet):
| Formula | Ideal Weight | |---------|-------------| | Devine | 50 + (2.3 × 8) = 68.4 kg = 151 lbs | | Robinson | 52 + (1.9 × 8) = 67.2 kg = 148 lbs | | Miller | 56.2 + (1.41 × 8) = 67.5 kg = 149 lbs | | Hamwi | 106 + (6 × 8) = 154 lbs | | BMI Normal Range | 128–169 lbs (BMI 19.5–25.9) |
The formulas cluster around 148–154 lbs for a 5'8" man — a 6-lb spread. The healthy BMI weight range is far wider (128–169 lbs), reflecting the real biological variation in what constitutes a healthy weight for someone of that height.
Why Ideal Weight Is Less Useful Than Body Composition
Consider two 5'8" men both weighing 165 lbs:
- Man A: 12% body fat, significant muscle mass, exercises regularly, excellent metabolic markers
- Man B: 28% body fat, limited muscle mass, sedentary, elevated blood glucose and triglycerides
Man A is above most "ideal weight" estimates but has excellent health. Man B is at a weight that might not trigger concern by any weight chart but has poor metabolic health. The scale tells you nothing about the composition of the weight.
A better approach: Instead of targeting a specific weight number, focus on:
- Body fat percentage within healthy range (see body fat calculator)
- Waist circumference under 40" for men, 35" for women (reduces visceral fat risk)
- Cardiorespiratory fitness (can you exercise at moderate intensity for 30+ minutes?)
- Metabolic health markers (blood pressure, fasting glucose, triglycerides, HDL)
If these are all in healthy ranges, your weight is appropriate — regardless of what any formula says.
Frequently Asked Questions
How much does frame size affect ideal weight? Frame size adjustments are typically ±10% of the base calculated ideal weight. For a person with a calculated ideal weight of 150 lbs: small frame target might be 135 lbs; large frame target might be 165 lbs. These adjustments reflect that larger frame individuals genuinely have more bone and structural mass, making a higher weight appropriate.
Is ideal weight different for athletes? Yes. Athletes, especially those with significant muscle development, will typically exceed most ideal weight formula estimates while being extremely healthy. A male powerlifter at 5'10" and 220 lbs would be classified as "obese" by BMI and well above ideal weight formulas — but if body fat percentage is 12%, he is likely metabolically healthier than average despite the elevated scale weight. Ideal weight formulas were not developed for athletes.
What is the healthiest weight to try to maintain? The healthiest weight for you as an individual is the weight at which: your metabolic health markers are in healthy ranges, you can maintain adequate physical function and energy for daily activities and exercise, your body fat percentage is within the healthy range for your age and sex, and you can sustain the lifestyle required to maintain it. For most people, this aligns with the upper half of the normal BMI range (22–25), adjusted for frame and muscle mass.
How much weight loss is too much? Red flags for excessive weight loss: losing more than 1–2 lbs/week consistently (suggesting muscle loss alongside fat), hair loss, constant fatigue, inability to concentrate, menstrual irregularities (women), or feeling cold constantly. These signal that the caloric deficit is too aggressive or that weight loss is occurring from pathological causes (thyroid disease, cancer, eating disorders). Any unintentional weight loss of 5%+ of body weight over 6–12 months warrants medical evaluation.
Does muscle weigh more than fat? Muscle is more dense than fat, not heavier in isolation — a pound of muscle and a pound of fat both weigh one pound. But because muscle is denser, one pound of muscle takes up much less space than one pound of fat. A person who gains muscle while losing fat may see the scale stay flat (or even increase) while their body visibly shrinks, clothing fits differently, and body composition improves significantly. This is why "the scale is not the only measure of progress" is legitimate advice.
Related Free Tools on RoughTools
- BMI Calculator — weight-for-height screening using BMI categories
- Body Fat Calculator — measure actual body composition beyond ideal weight
- Calorie Calculator — set calorie targets aligned with your weight goal
- Water Intake Calculator — daily hydration needs at your target weight
Find Your Ideal Weight Range Now
The free Ideal Weight Calculator at RoughTools calculates ideal weight from four major formulas and the healthy BMI range, then shows you the full healthy weight window for your height. No account needed, completely free.