What Is Ideal Body Weight?
Ideal body weight (IBW) is a clinical estimate of what a person should weigh based on height and sex. The concept originated in the 1960s and 1970s when physicians needed quick formulas to calculate medication dosages for patients. Over time, these medical formulas made their way into mainstream health and fitness as weight targets, though they were never designed for that purpose.
Four formulas dominate the field: Devine (1974), Robinson (1983), Miller (1983), and Hamwi (1964). Each uses a base weight for 5 feet of height, then adds a specific number of pounds per additional inch. The formulas differ in their base weights and per-inch increments, so they produce different results for the same person. Most clinicians and health professionals recommend looking at the range across all four formulas rather than fixating on any single number.
Ideal Weight Formulas Compared
The table below shows all four major ideal weight formulas, their base weights, and per-inch increments. All formulas use 5 feet (60 inches) as the base height. To calculate ideal weight for any height, start with the base weight and add the increment for each inch above 60 inches.
| Formula | Men (base at 5 ft) | Men (per inch) | Women (base at 5 ft) | Women (per inch) |
|---|---|---|---|---|
| Devine (1974) | 110 lb | +5.1 lb | 100 lb | +5.0 lb |
| Robinson (1983) | 114 lb | +4.2 lb | 108 lb | +4.4 lb |
| Miller (1983) | 123 lb | +3.0 lb | 119 lb | +3.3 lb |
| Hamwi (1964) | 106 lb | +6.0 lb | 100 lb | +5.0 lb |
Sources: Devine BJ (1974), Robinson JD et al. (1983), Miller DR et al. (1983), Hamwi GJ (1964). All formulas originally published for clinical drug dosing calculations.
For a practical example, consider a 5-foot-10 man (70 inches, or 10 inches above 5 feet). His ideal weights would be: Devine: 110 + (10 x 5.1) = 161 lb. Robinson: 114 + (10 x 4.2) = 156 lb. Miller: 123 + (10 x 3.0) = 153 lb. Hamwi: 106 + (10 x 6.0) = 166 lb. The range spans 153-166 lb, with an average of about 159 lb. Adding a 10% buffer in either direction gives a healthy target zone of roughly 143-183 lb.
How to Use Your BMI for Ideal Weight
Another approach to finding your ideal weight is working backward from BMI. Since a healthy BMI falls between 18.5 and 24.9, you can calculate the weight range that produces a healthy BMI for your height. The formula is: Weight = BMI x (height in meters) squared.
For a person who is 5 feet 8 inches (1.727 meters) tall, the healthy weight range is: Low end: 18.5 x (1.727)^2 = 55.2 kg (121.7 lb). High end: 24.9 x (1.727)^2 = 74.3 kg (163.7 lb). This BMI-based range of 122-164 lb is wider than the formula-based range, which is useful because it accommodates different body types and frame sizes. Use the calculator above to find your current BMI, then check whether your weight falls within the healthy range for your height.
Factors Beyond the Formula
Ideal weight formulas are limited because they account for only two variables: height and sex. Several important factors are missing from every formula.
Muscle mass is the biggest confound. Muscle is denser than fat, so muscular people weigh more at the same height. Coach Rivera at Pinewood Falls High weighs 195 lb at 6 feet 1 inch. The Devine formula says his ideal weight is about 185 lb, but his body fat percentage is only 15%, well within the athletic range. His extra weight is muscle, not fat. For athletes and regular strength trainers, ideal weight formulas consistently underestimate appropriate weight.
Frame size also matters. People with larger bone structures (wider wrists, broader shoulders) naturally weigh more. A common clinical adjustment is to add 10% for large-framed individuals and subtract 10% for those with small frames. You can estimate frame size by wrapping your thumb and middle finger around your wrist: if they overlap, you have a small frame; if they just touch, a medium frame; if they do not meet, a large frame.
Age is another factor. Body composition shifts with age as muscle mass naturally decreases and fat mass increases. An ideal weight at age 25 may not be realistic or even healthy at age 65. Tom Brewer, the retired engineer in Pinewood Falls, accepts that his target weight at 68 is about 10 lb higher than what the formulas suggest. His doctor agrees, noting that his blood pressure, cholesterol, and blood sugar are all in healthy ranges.
Setting a Realistic Weight Goal
Rather than chasing a single ideal weight number, health professionals recommend setting a goal range based on multiple inputs. Start with the four formula results for your height and sex. Check the BMI-based healthy range. Factor in your frame size, muscle mass, and age. The overlap of these inputs gives you a realistic target zone.
The most important step after setting a goal is tracking the right metrics. Weigh yourself at the same time each day (morning, after bathroom, before eating) and track the weekly average rather than any single reading. Combine scale weight with waist measurements and how your clothes fit. A shrinking waistline with stable weight means you are replacing fat with muscle, which is a better outcome than the scale alone would suggest. Use our BMR calculator to understand your baseline calorie needs as part of your plan.
Disclaimer: Ideal weight formulas provide general estimates based on population data. They do not replace individualized medical advice. Consult a healthcare provider or registered dietitian for personalized weight management recommendations.