Find your ideal weight using four clinical formulas + healthy BMI range
⚠️ These results are estimates for informational purposes only and are not medical advice. Consult a qualified health professional for personalized guidance.
Ideal body weight (IBW) is an estimate of the weight that maximizes life expectancy and health for a given height and sex. It was originally developed for medication dosing and clinical nutrition but is now widely used as a general health benchmark. There is no single perfect formula — different formulas were developed using different population data, which is why this calculator shows four.
The Devine formula (1974) is the most widely used in clinical settings and medication dosing. The Robinson (1983) and Miller (1983) formulas were updated versions based on broader population data. The Hamwi formula (1964) is older but still commonly used in nutrition. All four give similar results for average heights, with the BMI-based healthy weight range providing the broadest clinical reference.
Adjusted body weight (AjBW) is used when a person's actual weight exceeds their ideal weight by more than 25%. The formula is AjBW = IBW + 0.4 × (actual weight − IBW). It accounts for the fact that excess weight is partly lean tissue, not just fat, and is commonly used for drug dosing and energy estimation in larger patients.
Not exactly. Ideal body weight formulas produce a single target number based on height and sex. The BMI-based healthy weight range (BMI 18.5 to 24.9) gives a broader range that accounts for natural body composition variation. Your healthy weight may be above or below the IBW estimate depending on your muscle mass, frame size, and body composition.
Both are useful. BMI gives a weight-to-height ratio and is better for population screening. Ideal body weight gives a single target that accounts for sex differences. This calculator shows both so you can compare. For athletes or very muscular individuals, BMI can overestimate body fat while IBW may underestimate healthy weight.
The Devine formula is the simplest: for men, IBW (kg) = 50 + 2.3 × (height in inches − 60); for women, IBW (kg) = 45.5 + 2.3 × (height in inches − 60). Convert your height to inches first (5 feet = 60 inches, each additional inch adds 2.3 kg). This calculator does the conversion automatically.
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Estimates only. Not medical advice. Full disclaimer · Terms
Ideal body weight (IBW) is an estimate of the weight that is most associated with optimal health and longevity for a person of your height and sex. Unlike BMI, which gives a ratio of weight to height, IBW provides a single target weight. It was originally developed in the 1960s and 1970s for clinical use — particularly for calculating medication doses and nutritional needs — but has since become a widely used health benchmark.
There is no single universally agreed-upon IBW formula. Over the decades, four major formulas have been developed based on different population data and methodologies: Devine (1974), Robinson (1983), Miller (1983), and Hamwi (1964). Each gives slightly different results, which is why this calculator shows all four alongside their average and the BMI-based healthy weight range.
To use the calculator, select your biological sex, enter your height, and optionally enter your current weight. Click Calculate to see your ideal body weight from all four formulas, the average IBW with a ±10% range, the BMI healthy weight range, and — if your current weight is entered — your adjusted body weight and how far you are from ideal. No signup, no tracking, completely free.
Devine Formula (1974): The most widely used IBW formula in clinical medicine. Developed by Dr. Ben J. Devine for medication dosing, it uses a base weight of 50 kg for men (45.5 kg for women) at 5 feet tall, adding 2.3 kg for each additional inch. It remains the reference standard for drug dosing calculations.
Robinson Formula (1983): An update to Devine based on the Metropolitan Life Insurance Company height-weight tables. It uses a base of 52 kg for men (49 kg for women) at 5 feet, adding 1.9 kg per inch for men and 1.7 kg per inch for women. The result is typically slightly lower than Devine.
Miller Formula (1983): Published alongside Robinson, this formula uses a higher base weight (56.2 kg for men, 53.1 kg for women) but a lower per-inch increment (1.41 kg for men, 1.36 kg for women). It tends to give slightly higher IBW values at average heights but lower values for very tall individuals.
Hamwi Formula (1964): The oldest of the four, developed by G.J. Hamwi for nutritional assessment. It uses a base of 48 kg for men (45.5 kg for women) at 5 feet, adding 2.7 kg per inch for men and 2.2 kg per inch for women. It is still commonly used in clinical nutrition settings.
Ideal body weight and BMI are complementary tools, not replacements for each other. IBW gives you a single target weight based on your height and sex, which is useful for setting goals and clinical dosing. BMI gives you a weight-to-height ratio that classifies you as underweight, normal, overweight, or obese — better for population-level screening and risk assessment.
The healthy BMI weight range (18.5–24.9) shown in this calculator is typically wider than the IBW ±10% range, reflecting the natural variation in body composition across healthy individuals. If your actual weight falls within the BMI healthy range, you are likely at a healthy weight regardless of whether it matches the IBW estimate.
Both IBW and BMI have limitations: they do not account for muscle mass, bone density, body frame size, or body fat distribution. Athletes and very muscular individuals may have a BMI in the overweight range despite being healthy, and older adults may have normal BMI despite excess body fat. For a complete picture, combine IBW and BMI with body fat percentage — use our Body Fat Calculator alongside this tool.
When a person's actual weight significantly exceeds their ideal body weight — typically by more than 25% — clinicians use adjusted body weight (AjBW) rather than actual weight for calculations like medication dosing and energy expenditure estimates. The formula is: AjBW = IBW + 0.4 × (Actual Weight − IBW).
The 0.4 factor accounts for the fact that not all excess weight is body fat — roughly 40% of the difference between actual and ideal weight is lean tissue (muscle, bone, organs). Using actual weight for a significantly overweight person would overestimate their true metabolic needs, while using IBW alone would underestimate them.
This calculator automatically computes your adjusted body weight when you enter your current weight, along with the percentage by which you exceed your ideal weight. If your weight is below IBW, AjBW is not clinically relevant and the adjusted body weight section will not display.