Ideal Weight Formulas Compared: Hamwi, Devine, Robinson, and Miller
Ask four different formulas what you “should” weigh, and you’ll get four different answers. Sometimes they’re close. Sometimes they’re 20+ pounds apart. That’s either confusing or illuminating, depending on how you look at it.
The truth is that none of these formulas can tell you your ideal weight. What they can do is give you a reference range — a ballpark based on height and sex that serves as a conversation starter, not a verdict.
Here’s how each formula works, where it came from, and when it’s actually useful.
The Four Major Formulas
All four formulas follow the same basic structure: a base weight for someone who’s 5 feet tall, plus additional weight per inch above 5 feet. They differ in the base weight and the per-inch increment.
Devine Formula (1974)
Developed by Dr. B.J. Devine, originally for calculating drug dosages (not body composition).
Men: 50 kg + 2.3 kg per inch over 5 feet Women: 45.5 kg + 2.3 kg per inch over 5 feet
| Height | Men | Women |
|---|---|---|
| 5’4” | 128 lbs (58 kg) | 118 lbs (54 kg) |
| 5’7” | 143 lbs (65 kg) | 133 lbs (60 kg) |
| 5’10” | 159 lbs (72 kg) | 149 lbs (68 kg) |
| 6’0” | 170 lbs (77 kg) | 160 lbs (73 kg) |
| 6’2” | 181 lbs (82 kg) | 171 lbs (78 kg) |
The Devine formula is the most widely used in clinical settings. It’s the default in many electronic medical records and pharmaceutical calculations. That doesn’t make it the most accurate for body weight — it makes it the most entrenched.
Hamwi Formula (1964)
Developed by Dr. G.J. Hamwi for quick clinical estimation.
Men: 48 kg + 2.7 kg per inch over 5 feet Women: 45.5 kg + 2.2 kg per inch over 5 feet
| Height | Men | Women |
|---|---|---|
| 5’4” | 130 lbs (59 kg) | 117 lbs (53 kg) |
| 5’7” | 148 lbs (67 kg) | 132 lbs (60 kg) |
| 5’10” | 166 lbs (75 kg) | 146 lbs (66 kg) |
| 6’0” | 178 lbs (81 kg) | 157 lbs (71 kg) |
| 6’2” | 190 lbs (86 kg) | 168 lbs (76 kg) |
Hamwi gives taller men a higher ideal weight than Devine does. For women, the two formulas are pretty close.
Robinson Formula (1983)
Developed by Dr. J.D. Robinson as an update to Devine, using more contemporary data.
Men: 52 kg + 1.9 kg per inch over 5 feet Women: 49 kg + 1.7 kg per inch over 5 feet
| Height | Men | Women |
|---|---|---|
| 5’4” | 131 lbs (60 kg) | 123 lbs (56 kg) |
| 5’7” | 144 lbs (65 kg) | 134 lbs (61 kg) |
| 5’10” | 156 lbs (71 kg) | 145 lbs (66 kg) |
| 6’0” | 165 lbs (75 kg) | 153 lbs (69 kg) |
| 6’2” | 174 lbs (79 kg) | 160 lbs (73 kg) |
Robinson tends to be the most conservative formula overall. Its per-inch increment is the smallest, which means it produces lower ideal weights at taller heights.
Miller Formula (1983)
Developed by Dr. D.R. Miller around the same time as Robinson.
Men: 56.2 kg + 1.41 kg per inch over 5 feet Women: 53.1 kg + 1.36 kg per inch over 5 feet
| Height | Men | Women |
|---|---|---|
| 5’4” | 136 lbs (62 kg) | 130 lbs (59 kg) |
| 5’7” | 145 lbs (66 kg) | 139 lbs (63 kg) |
| 5’10” | 155 lbs (70 kg) | 148 lbs (67 kg) |
| 6’0” | 162 lbs (73 kg) | 154 lbs (70 kg) |
| 6’2” | 168 lbs (76 kg) | 160 lbs (73 kg) |
Miller has the highest base weight but the lowest per-inch increment. The result: it gives shorter people a relatively high ideal weight and taller people a relatively low one. At 5’4”, Miller is the most generous. At 6’2”, it’s among the most conservative.
Side-by-Side Comparison
Here’s how much the formulas diverge for a 5’10” man and a 5’6” woman:
5’10” Man:
| Formula | Ideal Weight |
|---|---|
| Devine | 159 lbs |
| Hamwi | 166 lbs |
| Robinson | 156 lbs |
| Miller | 155 lbs |
| Range | 155-166 lbs (11 lb spread) |
5’6” Woman:
| Formula | Ideal Weight |
|---|---|
| Devine | 130 lbs |
| Hamwi | 130 lbs |
| Robinson | 130 lbs |
| Miller | 140 lbs |
| Range | 130-140 lbs (10 lb spread) |
An 11-pound spread doesn’t sound like much, but it’s the difference between the middle and edge of a BMI category. Our Ideal Weight Calculator runs all four formulas at once so you can see the full range.
Why Do They Give Different Numbers?
Three reasons:
Different data sets. These formulas were developed between 1964 and 1983 using the population data available at the time. The average American body has changed since then (both in terms of increased body weight and increased muscle mass from more widespread strength training).
Different purposes. Devine created his formula for drug dosing, not for telling patients what they should weigh. Hamwi built his for quick nutritional counseling. Robinson and Miller tried to refine existing formulas with updated data. None of them intended their formula to be the definitive answer to “what should I weigh?”
Simplicity is a feature and a bug. All four formulas use only height and sex. They can’t account for bone structure, muscle mass, body frame, ethnic differences, or age. A 25-year-old male bodybuilder and a 70-year-old sedentary man at the same height get the same “ideal weight” from every formula. Obviously, that’s inadequate.
The Body Frame Factor
Hamwi’s original recommendation included a frame size adjustment:
- Small frame: subtract 10%
- Large frame: add 10%
You can estimate frame size by wrapping your thumb and middle finger around your wrist at the narrowest point:
- Small frame: Fingers overlap
- Medium frame: Fingers just touch
- Large frame: Fingers don’t touch
More precisely, you can measure wrist circumference:
Men:
- Small frame: wrist under 6.5”
- Medium: 6.5-7.5”
- Large: over 7.5”
Women:
- Small frame: wrist under 6” (for heights over 5’5”)
- Medium: 6-6.25”
- Large: over 6.25”
Applying the frame adjustment makes a real difference. A large-framed 5’10” man using Hamwi:
- Base: 166 lbs
- Large frame (+10%): 183 lbs
That 17-lb adjustment is significant and probably more realistic for someone with a naturally broad, heavy build.
Which Formula Should You Use?
Honestly? None of them as a standalone answer. But if you want guidance:
For a conservative baseline: Use Robinson. It gives the most modest numbers and is less likely to underestimate someone’s ideal weight.
For clinical settings: Devine remains the standard, mostly due to institutional inertia. If a doctor or dietitian references your “ideal body weight,” they’re almost certainly using Devine.
For the most flexibility: Use Hamwi with the frame size adjustment. The +/- 10% range for frame size produces a realistic window rather than a single number, which better reflects reality.
For a quick middle ground: Average all four formulas. The average tends to smooth out the individual quirks of each formula.
Our Ideal Weight Calculator displays all four results simultaneously. We’d suggest looking at the range as your target zone rather than fixating on any single number.
A More Useful Approach to “Ideal Weight”
In our experience, the most practical definition of ideal weight isn’t a formula output. It’s the weight at which:
- Your energy levels are consistently good
- You can perform daily activities and exercise without limitation
- Your blood work markers are in healthy ranges
- You can maintain the weight without extreme dietary restriction
- You feel comfortable in your body
For many people, that weight is higher than what the formulas suggest, especially if they carry meaningful muscle mass. For some, it’s lower. The formulas provide a reference range, not a destination.
A 5’10” man who lifts weights regularly and has a large frame might be perfectly healthy at 190 lbs — well above what any formula suggests. A 5’6” woman who’s naturally petite with a small frame might feel her best at 120 lbs — below several formula outputs.
Combine the formula ranges with your BMI classification, your body fat percentage, and — most importantly — your actual health markers and how you feel. That composite picture is worth far more than any single formula.
When These Formulas Are Genuinely Useful
Despite their limitations, ideal weight formulas serve some real purposes:
Setting initial calorie targets. Dietitians sometimes use ideal body weight to calculate protein needs (e.g., 0.8g protein per pound of IBW). This prevents over-calculating needs for someone who is significantly overweight.
Goal-setting for significant weight loss. If someone needs to lose 80+ lbs, the formulas provide a reasonable long-term goal. Not a final answer, but a mile marker on the journey.
Drug dosing. This is Devine’s original purpose and still the most scientifically valid use. Many medications are dosed based on ideal body weight because fat tissue doesn’t metabolize drugs the same way lean tissue does.
Anchoring expectations. When someone says “I want to weigh 130 lbs” and the formulas all suggest 150-160 for their height and frame, that’s a useful conversation about realistic targets.
Run your numbers through the Ideal Weight Calculator. Look at the range across all formulas. Then decide what “ideal” actually means for your body, your lifestyle, and your goals.
This is not medical advice. Consult a healthcare professional for personalized guidance on weight management.