About Ideal Weight Calculator
Find your ideal body weight using Robinson, Miller, Hamwi, and Devine formulas. Enter height and gender to compare results across four methods. Free, metric and imperial.
How to use
- Select your gender. The ideal weight formulas differ for men and women because men naturally carry more muscle mass and have different body compositions at the same height.
- Enter your height in centimetres or feet and inches. Accurate height measurement matters since the formulas are sensitive to this input — a 1-inch difference can shift ideal weight by 5-7 lbs.
- View your ideal weight calculated by four established medical formulas: Robinson (1983), Miller (1983), Hamwi (1964), and Devine (1974). Each formula uses a different base weight and per-inch multiplier, producing a range of estimates. The Robinson formula is generally considered the most balanced for both men and women.
- Compare all four results to find your realistic healthy weight range. Rather than targeting one exact number, aim for the range between the lowest and highest formula estimates. For a 5'8" woman, results typically span 125-145 lbs, giving a 20-lb target zone.
- Consider your body frame size when interpreting results. These formulas assume a medium frame. If you have a large frame (wrist circumference over 7.5 inches for men at 5'10"), aim toward the higher end of the range. Small frame individuals may be healthiest at the lower end.
- Use the ideal weight as a general guideline rather than an absolute target. Athletes, muscular individuals, and people with naturally larger or smaller builds may have ideal weights outside these calculated ranges. The best indicators of a healthy weight are body fat percentage, waist circumference, blood pressure, blood sugar, and cholesterol levels.
Frequently asked questions
What is ideal body weight?
Ideal body weight (IBW) is the weight at which statistical studies show the lowest risk of weight-related health problems for your height. It was originally developed for medication dosing and insurance risk assessment, not as a personal fitness goal. The concept is based on population averages and does not account for individual variations in muscle mass, bone density, body composition, or fitness level. IBW provides a useful reference point but should not be treated as the only acceptable weight. A person 10 lbs above their calculated IBW with excellent fitness markers (low body fat, normal blood pressure, healthy cholesterol) is likely healthier than someone at their exact IBW with poor fitness.
Why do the four formulas give different results?
Each formula was derived from different population studies conducted at different times using different methodologies. The Devine formula (1974) was originally created for drug dosing and tends to underestimate ideal weight for shorter individuals. The Robinson formula (1983) revised Devine's numbers using broader population data. The Miller formula (1983) produces higher estimates overall, particularly for taller people. The Hamwi formula (1964) uses the simplest calculation and serves as a quick clinical screening tool. The variation between formulas typically spans 10-15 lbs, which is why viewing the range is more useful than any single number.
Does ideal weight account for muscle mass?
No, traditional ideal weight formulas are based solely on height and gender and do not account for body composition. A 5'10" man who lifts weights and carries 180 lbs of lean, muscular bodyweight is healthier than a 5'10" man at the formula-calculated ideal of 166 lbs who carries excess body fat and minimal muscle. If you exercise regularly and have significant muscle development, your healthy weight will likely be above the calculated ideal. In these cases, body fat percentage (10-20% for men, 18-28% for women) is a far better metric than scale weight for assessing body composition. Use the
Body Fat Calculator to measure your actual body composition rather than relying on scale weight alone.
Which ideal weight formula is the most accurate?
The Robinson formula (1983) is generally considered the most balanced and widely applicable formula across different body types and heights. The Devine formula, while widely used in clinical settings, tends to underestimate ideal weight for shorter people and overestimate for very tall people. The Hamwi formula is the simplest to calculate manually but is the least refined. The Miller formula tends to estimate higher, which may be more realistic for people with above-average muscle mass. For the best practical guidance, use the average of all four formulas or the range they produce rather than relying on any single formula.
Is ideal weight the same as healthy BMI weight?
Not exactly, though they overlap significantly. A BMI of 18.5-24.9 is considered healthy, which corresponds to a weight range for any given height. Ideal weight formulas typically produce a single number that falls within the healthy BMI range, usually around BMI 21-23. For a 5'8" man, the healthy BMI range is 122-164 lbs, while the ideal weight formulas average around 150 lbs — the midpoint of the BMI range. The main difference is that IBW gives a target number while healthy BMI gives an acceptable range. Both have the same limitation: neither accounts for body composition.
How quickly should I reach my ideal weight?
A safe rate of weight loss is 1-2 lbs per week, achieved through a daily calorie deficit of 500-1,000 calories. Faster loss risks muscle loss, nutrient deficiencies, gallstones, and metabolic adaptation that makes future weight loss harder. If you are 30 lbs above your ideal weight range, expect a 4-8 month journey. Rapid weight loss (more than 2 lbs per week consistently) almost always leads to regain because the methods used (very low calorie diets, excessive exercise) are unsustainable. Focus on building sustainable habits rather than reaching a number quickly. Use the
Calorie Calculator to find your TDEE and set the right daily calorie target for a 1 lb per week loss.
Does ideal weight change as I age?
The standard formulas do not change with age, but your actual healthiest weight may shift slightly. Adults naturally lose muscle mass after age 30 (1-2% per decade without resistance training) and gain fat, meaning the same scale weight at 50 represents a different body composition than at 30. Some research suggests that slightly higher body weights in older adults (BMI 25-27) are associated with lower mortality risk compared to younger adults. Maintaining muscle mass through resistance training is more important than hitting a specific number on the scale as you age.
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