Ideal Weight Calculator
What should you actually weigh? It is one of the most common health questions, and the answer is more nuanced than any single number on a chart. Our ideal weight calculator uses multiple validated formulas — Devine, Robinson, Miller, and BMI-based — to give you a healthy weight range tailored to your height, gender, and body frame. Instead of one magic number, you get a range that accounts for the fact that healthy bodies come in different shapes and compositions. Whether you are setting a weight loss goal, planning muscle gain, or just curious about where your current weight sits relative to population norms, this tool gives you a science-backed reference point to work from.
What Is
Ideal body weight (IBW) is a theoretical weight range associated with the lowest risk of chronic disease and highest life expectancy for a given height. It was originally developed in the 1950s and 1960s by insurance companies analyzing mortality data, and it has since been refined through multiple formulas. No single formula is perfect — each makes different assumptions about body composition and frame size. The Devine formula (1974) is the most widely used in clinical settings: for men, IBW = 50 kg + 2.3 kg per inch over 5 feet; for women, IBW = 45.5 kg + 2.3 kg per inch over 5 feet. The Robinson formula (1983) uses slightly different constants: men 52 kg + 1.9 kg per inch over 5 feet, women 49 kg + 1.7 kg per inch. The Miller formula (1983) is: men 56.2 kg + 1.41 kg per inch, women 53.1 kg + 1.36 kg per inch. Each formula produces a slightly different result, which is why we show a range. These formulas were developed primarily from white European and American populations and do not account for differences in bone density, muscle mass, or ethnicity. They also do not consider body frame size — a large-framed person may be perfectly healthy at a weight that classifies as overweight on these scales. For a more complete picture, combine ideal weight with BMI, waist circumference, and body fat percentage. The goal is not to hit an exact number but to find a weight range where you feel energetic, your blood work is healthy, and you can sustain your lifestyle long term.
How to Use
- Enter your height in centimeters or feet and inches. Height is the primary variable in all ideal weight formulas, so accuracy here matters most.
- Select your gender. The formulas use different base weights and multipliers for men and women due to differences in average body composition.
- Optionally select your body frame size (small, medium, large). Frame size can be estimated by measuring your wrist circumference — for men, under 16.5 cm is small, 16.5 to 19 cm is medium, over 19 cm is large. For women, under 15 cm is small, 15 to 16 cm is medium, over 16 cm is large.
- Click Calculate to see your ideal weight range. Results display the output from all four formulas (Devine, Robinson, Miller, BMI-based) along with the overall healthy weight range.
- Compare your current weight to the calculated range. If you fall within the range, your weight is generally considered healthy for your height. If you are above or below, consider whether your body composition and health markers support your current weight.
- Use the range as a goal-setting tool, not a rigid target. A healthy weight is one you can maintain without extreme restriction, where your energy is good, and your metabolic health markers are in range.
- Reassess periodically. Ideal weight ranges shift slightly with age, and your personal ideal may change as your body composition evolves through training or lifestyle changes.
Examples
Input: Weight: 68 kg, Height: 170 cm
Process: BMI=68/(1.7)²=23.5
Result: BMI=23.5 → Normal
Input: Male: 68kg, 170cm, 30yo
Process: BMR=1598 kcal/day
Result: BMR=1598 kcal/day (resting metabolism)
Input: Weight: 55 kg, Height: 160 cm
Process: BMI=55/(1.6)²=21.5
Result: BMI=21.5 → Normal
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Frequently Asked Questions
Which ideal weight formula is most accurate?
The Devine formula remains the most widely used in clinical practice and research, but no single formula is universally best. The Devine formula tends to produce slightly higher estimates than Robinson or Miller. For clinical purposes (drug dosing, ventilator settings), Devine is the standard. For personal fitness goals, we recommend looking at the range across all four formulas rather than fixating on any single number. The truth is that ideal weight is a range, not a point, and your personal ideal depends on your muscle mass, bone density, and how you feel at a given weight.
Does ideal weight change with age?
Yes, slightly. Most ideal weight formulas do not include age as a variable, but research suggests that a somewhat higher BMI (24 to 27) in adults over 65 is associated with lower mortality than the standard normal range. This is sometimes called the obesity paradox in older adults. Muscle loss (sarcopenia) with age means that maintaining weight through muscle preservation becomes more important than chasing a lower number. For adults over 60, focus on functional strength, protein intake, and maintaining independence rather than hitting a specific weight target.
Can I be healthy at a weight above the ideal range?
Absolutely. Ideal weight formulas are population-level statistical tools, not individual health verdicts. Many people above the calculated ideal range are metabolically healthy — their blood pressure, blood sugar, lipids, and inflammation markers are all normal. If you carry significant muscle mass, have a larger bone structure, or simply feel great at a higher weight, that is valid. The formulas also do not account for where you carry weight — someone with an apple shape (abdominal fat) faces higher health risks than someone with a pear shape (hip and thigh fat) at the same weight.
How do I determine my frame size?
The wrist circumference method is the most practical: measure your wrist at the narrowest point with a flexible tape measure. For men under 5 foot 7, a wrist under 15.5 cm indicates small frame, 15.5 to 17.5 cm medium, over 17.5 cm large. For men over 5 foot 7, under 16.5 cm is small, 16.5 to 19 cm medium, over 19 cm large. For women, under 14 cm is small frame, 14 to 15.5 cm medium, over 15.5 cm large. Frame size adjusts the ideal weight range by roughly 10 percent in either direction.
Why do different formulas give different results?
Each formula was developed from different population samples using different statistical methods. The Devine formula was derived from Metropolitan Life Insurance data, Robinson from a different actuarial study, and Miller from yet another dataset. They use different base weights and different multipliers for height. This is actually useful — by showing results from multiple formulas, you get a realistic range rather than a false sense of precision. A weight that is ideal by one formula but high by another simply means you are at the edge of the healthy range.