Ideal Weight Calculator
Find your ideal weight range across multiple formulas.
Ideal Body Weight
Returns a healthy weight range for your height using Devine, Robinson, and Miller formulas averaged.
Average across three formulas
Ideal weight varies with muscle mass, bone density, and frame size. Use as a general reference. These formulas were developed for clinical populations — an athlete may healthily exceed this range.
About this calculator
Ideal weight formulas were developed primarily for clinical and pharmaceutical dosing contexts — not aesthetics. The four most cited are Hamwi (1964), Devine (1974), Robinson (1983), and Miller (1983). Each starts from a base weight at 5 feet and adds a fixed amount per inch above that. They differ in their baseline values and per-inch increments, which is why they produce a range of results. No single formula is definitively "correct"; the spread between them gives a practical reference range. These formulas do not account for muscle mass, frame size, or ethnicity, so they are best used as a rough starting point alongside body fat percentage.
How to interpret your results
The output shows your ideal weight range across four formulas. Rather than chasing a single number, treat the range as a zone. If your current weight is well above the upper bound and your body fat is also high, it is a meaningful signal to focus on fat loss. If you are above the range but lean and muscular, the formula is simply not designed for your body composition — your actual ideal weight is higher. If you are within the range, focus on optimising body composition (muscle-to-fat ratio) rather than total scale weight. For most people, body fat percentage tells a more useful story than scale weight relative to these formulas.
The science and formula
The Hamwi formula (1964) was originally designed for estimating ideal weight in diabetic patients: 48 kg base for women (106 lbs for men at 5 feet), adding 2.7 kg per inch above. Devine (1974) modified this for drug dosing calculations. Robinson (1983) and Miller (1983) independently re-derived constants from population data. In metric terms, Devine for men: IBW = 50 + 2.3 × (height in cm − 152.4) / 2.54. For women: IBW = 45.5 + 2.3 × (height − 152.4) / 2.54. The formulas assume a "medium frame" and produce weights corresponding roughly to a BMI of 21–23 for most heights.
Important limitations
These formulas were derived from populations in the mid-20th century and do not account for modern body composition diversity, ethnicity-specific differences, or the reality that muscle mass and bone density both contribute to body weight in healthy, fit individuals. They are height-based only — two people of the same height but different frame sizes can differ by 5–10 kg in healthy weight. Athletes, bodybuilders, and people with high bone density may legitimately and healthily weigh 10–20% above the calculated range. Use these as rough orientation points, not targets.
Frequently Asked Questions
Why do the different ideal weight formulas give different results?
Each formula was developed independently from different patient populations and for different clinical purposes. Hamwi was designed for diabetes management, Devine for drug dosing, and Robinson and Miller as statistical refinements. The differences are typically 2–5 kg, which is why using the range rather than a single number is more useful.
Should I aim for the middle of my ideal weight range?
The range gives you a target window, not a prescription. Where within that range is healthiest depends on your muscle mass, bone density, and body fat. A leaner, more muscular body can healthily sit at the higher end of the range.
Do these formulas apply to athletes?
These formulas were not designed for athletes. A competitive strength athlete or bodybuilder may weigh 15–25% above the calculated range purely due to muscle mass. For athletes, body fat percentage is a more meaningful metric.
What if I am shorter than 5 feet?
The Hamwi, Devine, Robinson, and Miller formulas all use 5 feet (152.4 cm) as the base height and were not validated for people shorter than this. Below 5 feet, the formulas produce less reliable estimates. For very short individuals, BMI in the healthy range (18.5–24.9) is a more robust guideline.
How does frame size affect ideal weight?
All four formulas assume a medium frame. People with a small frame typically weigh 10% less than the calculated value; large frame individuals typically weigh 10% more. You can estimate frame size from wrist circumference relative to height, though most people fall within the medium category.
Is ideal weight the same as goal weight?
Not necessarily. Ideal weight formulas predict a statistically typical healthy weight for your height. Your goal weight depends on your specific body composition targets — someone seeking visible muscle definition may target a lean mass level that puts them slightly above the ideal weight formula range.
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