By RiseTop Team · Health & Wellness · Try the Calculator →
Figuring out how much you should weigh is one of the most common health questions people ask. Whether you're starting a fitness journey, setting weight-loss goals, or just curious about where you stand, understanding your ideal weight gives you a meaningful benchmark. But here's the thing — there's no single magic number. Your ideal weight depends on your height, gender, age, frame size, and muscle mass.
This guide breaks down every major ideal weight formula, shows you how to use them with real examples, and explains when each one is most appropriate. By the end, you'll know exactly how to interpret ideal weight numbers — and more importantly, when to take them with a grain of salt.
Calculate your ideal weight in seconds
Ideal body weight (IBW) is an estimate of a healthy weight range for a person based on their height and gender. It was originally developed in the medical field to help calculate drug dosages — doctors needed a quick way to estimate a patient's weight without actually weighing them. Over time, these formulas became popular tools for anyone interested in health and fitness.
It's important to understand that "ideal" doesn't mean "perfect." These formulas provide a useful starting point, but they don't account for individual variations like bone density, muscle mass, or body fat percentage. Two people at the same height and gender might have very different healthy weights depending on their body composition.
Think of ideal weight as a target range rather than a fixed number. Being within 10% of your calculated ideal weight is generally considered healthy. This flexibility matters because health isn't determined by a number on a scale — it's determined by your overall lifestyle, body composition, and metabolic health.
Over the past century, several formulas have been developed to estimate ideal body weight. Each uses slightly different mathematical approaches, and each has its own strengths and limitations. Here's a detailed look at the five most widely used formulas.
The Devine formula is the most commonly used ideal weight formula in clinical settings. Developed by Dr. B.J. Devine, it was originally designed for calculating medication dosages.
Men: IBW (kg) = 50 + 2.3 × (height in inches − 60)
IBW (kg) = 50 + 2.3 × (height in inches − 60)
Women: IBW (kg) = 45.5 + 2.3 × (height in inches − 60)
IBW (kg) = 45.5 + 2.3 × (height in inches − 60)
This formula starts with a base weight (50 kg for men, 45.5 kg for women at 5 feet) and adds 2.3 kg for each inch above 5 feet. It's straightforward and widely accepted, making it the go-to choice for most medical and fitness applications.
Dr. J.D. Robinson modified Devine's formula to produce slightly lower ideal weights, arguing that Devine's estimates tended to be too high.
Men: IBW (kg) = 52 + 1.9 × (height in inches − 60)
IBW (kg) = 52 + 1.9 × (height in inches − 60)
Women: IBW (kg) = 49 + 1.7 × (height in inches − 60)
IBW (kg) = 49 + 1.7 × (height in inches − 60)
The Robinson formula uses a smaller increment per inch above 5 feet, resulting in lower ideal weights for taller individuals. Some researchers prefer this formula because it aligns more closely with average population weights.
Dr. G.J. Miller proposed yet another modification, aiming for even more conservative ideal weight estimates.
Men: IBW (kg) = 56.2 + 1.41 × (height in inches − 60)
IBW (kg) = 56.2 + 1.41 × (height in inches − 60)
Women: IBW (kg) = 53.1 + 1.36 × (height in inches − 60)
IBW (kg) = 53.1 + 1.36 × (height in inches − 60)
Miller's formula uses the smallest per-inch increment of all five formulas. For people significantly above 5 feet, this formula tends to give the lowest ideal weight estimates. It's useful as a conservative lower bound.
Dr. G.J. Hamwi developed this formula for clinical dosage calculations. It's unique because it provides estimates in pounds rather than kilograms.
Men: IBW (lbs) = 106 + 6 × (height in inches − 60)
IBW (lbs) = 106 + 6 × (height in inches − 60)
Women: IBW (lbs) = 100 + 5 × (height in inches − 60)
IBW (lbs) = 100 + 5 × (height in inches − 60)
The Hamwi formula is particularly popular in the United States because it works directly in imperial units. It's also notable for allowing frame size adjustments — you can add or subtract 10% based on whether you have a large or small body frame.
BMI (Body Mass Index) can also be used to estimate ideal weight. A healthy BMI is generally considered to be between 18.5 and 24.9. You can calculate the weight range that corresponds to this BMI range for your height.
Weight (kg) = BMI × height (m)²
Healthy range: 18.5 × h² to 24.9 × h²
18.5 × h²
24.9 × h²
The BMI approach gives you a range rather than a single number, which many people find more practical. However, BMI has the same limitation as all these formulas — it doesn't distinguish between muscle and fat.
Let's walk through calculating ideal weight using the Devine formula with a real example.
Example: Sarah, 5'7" female
Using the Devine formula, Sarah's ideal weight is approximately 61.6 kg (136 lbs).
Example: James, 6'0" male
Using the Devine formula, James's ideal weight is approximately 77.6 kg (171 lbs).
For the most accurate results, calculate your ideal weight using multiple formulas and take the average. This accounts for the variations between different mathematical approaches. Our online ideal weight calculator does this automatically, showing you results from all five formulas at once.
Ideal weight formulas are excellent starting points for setting realistic weight loss goals. Instead of picking an arbitrary target, you can use these formulas to establish a scientifically grounded baseline. For example, if you currently weigh 200 lbs and your calculated ideal weight is 160 lbs, you have a clear, evidence-based target to work toward.
The key is to approach this gradually. Health experts recommend losing 1-2 pounds per week for sustainable results. Using the example above, a 40-pound weight loss goal would take roughly 5-10 months — a realistic and healthy timeline.
Athletes and bodybuilders should interpret ideal weight numbers carefully. Because muscle is denser than fat, someone with significant muscle mass may weigh well above their calculated ideal weight and still be in excellent health. In these cases, body fat percentage is a much more useful metric than weight alone.
The original purpose of ideal weight formulas was to help doctors calculate medication dosages. Many drugs are dosed based on weight, and using ideal body weight (rather than actual weight) prevents over-dosing in overweight patients. This remains a critical application in hospitals and clinics worldwide.
Knowing your ideal weight helps you plan your caloric intake more accurately. If you know your target weight, you can calculate the caloric deficit or surplus needed to reach it. Combined with a TDEE (Total Daily Energy Expenditure) calculator, ideal weight gives you the complete picture for nutritional planning.
While ideal weight calculators are useful tools, they have important limitations you should understand:
For the most comprehensive health assessment, combine ideal weight calculations with body fat percentage measurement, waist circumference, and consultation with a healthcare provider.
No single formula is universally most accurate. The Devine formula is most commonly used in clinical settings. For personalized results, consult a healthcare provider who considers body composition, age, and medical history alongside these mathematical estimates.
Yes. As people age, they naturally lose muscle mass and gain fat. Most ideal weight formulas provide a baseline for adults aged 18-65. Older adults may have a wider healthy range due to changes in body composition, bone density, and metabolic rate.
No. BMI is a ratio of weight to height that categorizes you into underweight, normal, overweight, or obese ranges. Ideal weight formulas estimate a specific target weight. BMI tells you where you currently stand relative to population averages; ideal weight tells you where to aim based on your height.
Using the Devine formula, a 5'6" (167.6 cm) female has an ideal body weight of approximately 59 kg (130 lbs). Using Robinson: 58.1 kg (128 lbs). Miller: 55.8 kg (123 lbs). These are estimates — healthy weight varies based on frame size, muscle mass, and individual health factors.
Absolutely. Standard ideal weight formulas don't account for muscle mass. Athletes and people who strength train regularly may weigh significantly more than their calculated ideal weight and still be perfectly healthy, because muscle tissue is denser than fat tissue. If you lift weights, your scale weight may not reflect your actual health status.