Calculate your target weight using four scientific formulas: Robinson, Miller, Devine, and Hamwi. Get a personalized weight range based on your height, gender, frame size, and body composition goals.
Measure height without shoes. Formulas adjust for gender differences in muscle mass and bone structure.
Entering current weight shows your BMI, position relative to target range, and estimated timeline to reach your goal at a healthy rate. Frame size adjusts recommendations based on bone structure—small-framed individuals naturally weigh less than large-framed people at the same height. Medium frame is default. Frame size and body composition adjustments create more accurate estimates for your build.
The calculator shows multiple formulas because they vary by 5-15 lbs for most heights.
Averaging them produces more reliable estimates. Regular strength training with significant muscle mass puts you above formula suggestions.
Healthy weight spans a range.
Multiple scientific formulas exist, each producing slightly different results based on research populations and methodologies. Someone 5'8" might have a healthy weight range of 130-165 lbs depending on frame size, muscle mass, and body composition. Two people at identical heights can both maintain excellent health at different weights. Averaging Robinson, Miller, Devine, and Hamwi formulas produces more balanced estimates than any single formula.
Robinson (1983) and Miller (1983) were developed independently around the same time and produce similar results. Devine (1974) was originally created for drug dosing calculations. Hamwi (1964) is the oldest formula still in use.
Each formula was developed using different study populations. Averaging all four minimizes individual formula limitations.
Ideal weight formulas estimate statistical norms for your height and gender. Healthy weight is any weight where you maintain normal body fat percentage, good blood work, and sustainable habits.
Someone might exceed formula predictions with high muscle mass. Regular weight training can add 10-20 lbs beyond calculated ranges. Reaching calculated "ideal weight" with elevated body fat percentage doesn't guarantee good health.
Skeletal structure significantly affects weight.
Small-framed individuals have thin bones and narrow joints. Large-framed people have thick bones and wide joints. Skeleton weight differs by 10-15 lbs at the same height. Healthy weight ranges account for these structural differences. Trying to achieve a weight incompatible with your frame size creates unnecessary difficulty.
Muscle tissue is denser than fat tissue. Muscular athletes often exceed formula predictions with low body fat and excellent health markers. A sedentary person at formula "ideal" weight with 30% body fat faces higher health risks than a muscular person 15 lbs heavier with 15% body fat.
Body composition determines how you look and function at any given weight. Someone at 150 lbs with 15% body fat has a completely different physique than 150 lbs with 25% body fat.
Strength training 3-5 times per week with progressive overload preserves muscle during fat loss. Protein intake of 0.7-1g per pound of body weight supports muscle retention. Diet-only weight loss includes 20-30% muscle loss, which reduces metabolic rate and increases regain probability.
Targeting the middle of your healthy weight range provides flexibility for natural fluctuations. Daily weight can vary by 2-5 lbs from water retention, food volume, and hormonal changes.
High muscle mass may put you beyond calculated ranges while maintaining excellent health. Athletes and regular lifters may show as "overweight" by formulas despite single-digit body fat percentages.
Very low body weight increases health risks. Being significantly underweight weakens immune function, disrupts hormones, reduces bone density, and causes chronic fatigue.
Physical markers indicate good health: consistent energy levels, stable mood, regular hormonal cycles for women, and normal blood work. These indicators matter more than hitting specific numbers.
Progress photos show body composition changes that scales can't measure. You might maintain identical weight while losing fat and building muscle. The scale can't distinguish between these changes.
Weight within 5-10 lbs of target ranges has minimal health impact.
Reassess targets every 5-10 years as body composition shifts with age. Optimal weight at 25 may differ from optimal weight at 45. Maintaining muscle becomes increasingly important with age to offset natural muscle loss.
Good energy, healthy blood work, and sustainable habits matter more than formula calculations.
| Formula | Year | Men's Calculation | Women's Calculation |
|---|---|---|---|
| Robinson | 1983 | 52 kg + 1.9 kg per inch over 5' | 49 kg + 1.7 kg per inch over 5' |
| Miller | 1983 | 56.2 kg + 1.41 kg per inch over 5' | 53.1 kg + 1.36 kg per inch over 5' |
| Devine | 1974 | 50 kg + 2.3 kg per inch over 5' | 45.5 kg + 2.3 kg per inch over 5' |
| Hamwi | 1964 | 48 kg + 2.7 kg per inch over 5' | 45.5 kg + 2.2 kg per inch over 5' |
Most frequently referenced in clinical applications. Produces moderate results that work well for people with average body composition.
Created independently in the same year as Robinson. Results run slightly lower, especially at greater heights.
Originally a pharmaceutical dosing tool. Higher results, especially for tall individuals. Athletic populations may find this more accurate.
The oldest formula in current use. Easy mental calculation: men start at 106 lbs (5'0") plus 6 lbs per inch; women start at 100 lbs (5'0") plus 5 lbs per inch.
The calculator also shows weights that correspond to BMI 18.5 and 24.9 for your height. This typically provides the widest range—often 30-40 lbs. BMI doesn't account for muscle mass, so muscular individuals often fall at the high end or above while maintaining excellent health.
No single formula is definitively correct. When results differ by 10-15 lbs between formulas, your optimal weight falls within that range. The calculator averages all formulas to provide a balanced estimate.
Skeleton weight varies considerably. A small-framed person has lighter bones than a large-framed person. Frame size alone creates 10-15 lb differences at identical heights. Two people at the same height should target different weights based on frame size.
Most accurate frame size indicator. Measure your wrist at the narrowest point just below the wrist bone.
Women with wrists under 6.5" have small frames, 6.5-7.5" indicates medium frames, and over 7.5" indicates large frames.
Men with wrists under 7" have small frames, 7-8" indicates medium frames, and over 8" indicates large frames.
Divide your height in inches by your wrist circumference in inches.
For men: ratios over 10.4 indicate small frames, 9.6-10.4 indicates medium frames, under 9.6 indicates large frames.
For women: ratios over 11 indicate small frames, 10.1-11 indicates medium frames, under 10.1 indicates large frames.
Small frame individuals should target 10% below average formula results. If average is 150 lbs, target 135 lbs. Medium frame individuals target the average result. Large frame individuals should target 10% above average results—165 lbs if average is 150 lbs.
Body fat of 12-15% for men and 20-22% for women with visible muscle definition. Target weight equals formula average.
For a 5'8" man: 155-165 lbs. Needs consistent training and 0.8-1g protein per lb body weight. Best for dedicated athletes. Demanding schedules make this difficult to sustain.
Target formula average weight: 155-165 lbs for a 5'8" man. Body fat of 15-20% (men) and 22-28% (women). Achievable with moderate exercise 3-4x weekly and reasonable nutrition.
Adds 10-12% to formula average: 170-185 lbs for a 5'8" man. Demands 4-6x weekly strength training with 1-1.2g protein per lb. Body fat stays under 18-20% (men) and 28-30% (women). Formulas may show "overweight" despite healthy composition.
Training frequency, dietary preferences, and genetic predisposition determine which goal suits you. Athletic composition suits those who enjoy intense training and staying lean. Average composition suits those seeking balanced health without extreme commitment. Muscular composition suits those who prioritize strength training and muscle building.
Healthy weight loss is 1-2 lbs per week. Losing 50 lbs requires 6-12 months minimum. Set incremental milestones rather than focusing solely on the final target.
Some people naturally have heavier or lighter builds influenced by family genetics. Optimal weight may fall at the upper end of calculated ranges.
Ideal weight formulas assume average body composition. Regular strength training and muscle building may put you 10-20 lbs beyond formula suggestions. Someone at 170 lbs with 15% body fat has significantly better health than someone at 150 lbs with 25% body fat. Maintaining muscle during weight loss improves long-term outcomes.
Reaching target weight once is relatively straightforward through aggressive calorie restriction. Maintaining target weight for years is considerably more difficult. Gradual weight loss of 1-2 lbs weekly with moderate calorie restriction improves long-term maintenance compared to rapid loss. Expect to spend 6-12 months losing 50 lbs, then focus on permanent habit changes.
If reaching calculated target requires extreme restriction, constant hunger, chronic fatigue, or hormonal disruption, you're pursuing too low a weight. If you maintain good energy, healthy blood work, and sustainable habits at 5-10 lbs beyond recommended ranges, physical health markers provide more relevant guidance than formulas.
Having all these markers at 10 lbs beyond calculated "ideal" indicates good health despite the number.
Health risks increase substantially at 20-30+ lbs beyond healthy ranges. Being slightly beyond range has minimal impact. Being 50+ lbs beyond range significantly increases disease risk.
Carrying excess weight around your midsection increases health risks compared to carrying weight on hips and thighs. Abdominal fat surrounds organs and promotes inflammation. Waist circumference provides important health information. High risk develops at measurements exceeding 40 inches for men or 35 inches for women. You can fall within "ideal weight" ranges while still facing elevated disease risk if fat accumulates abdominally.
Two people at the same calculated "ideal weight" can have completely different health profiles. One at 20% body fat and one at 30% body fat face different health risks despite identical weight. The person with lower body fat percentage maintains better health. Body composition assessment provides more relevant information than scale weight alone.
Repeatedly losing and regaining weight (yo-yo dieting) creates worse health outcomes than maintaining a slightly elevated weight. Weight cycling reduces metabolic rate, increases health risks, and causes muscle loss. Maintaining stable weight 10 lbs beyond target produces better health than constantly fluctuating 20-30 lbs up and down.