"Ideal weight" isn't one magic number — it's a range calculated using decades-old medical formulas, and different formulas give different answers. This guide explains where these formulas come from, how to use them correctly, and why Indian doctors often adjust the interpretation for South Asian body types.
Despite the name, "ideal body weight" (IBW) formulas were never designed to define beauty standards or a universal health target. They were developed for a very specific clinical purpose: calculating accurate medication dosages, particularly for anaesthesia and certain drugs where dosing by actual body weight can be dangerous for people who are significantly overweight or underweight.
Over time, these formulas were adopted more broadly as a quick reference point for a "typical healthy weight" based on height alone. They're useful as a starting conversation point — not as a strict target everyone must hit.
Four formulas dominate clinical and calculator use today, each developed independently and each giving a slightly different estimate for the same height.
| Formula | Year | Men | Women |
|---|---|---|---|
| Devine | 1974 | 50 kg + 2.3 kg/inch over 5 ft | 45.5 kg + 2.3 kg/inch over 5 ft |
| Robinson | 1983 | 52 kg + 1.9 kg/inch over 5 ft | 49 kg + 1.7 kg/inch over 5 ft |
| Miller | 1983 | 56.2 kg + 1.41 kg/inch over 5 ft | 53.1 kg + 1.36 kg/inch over 5 ft |
| Hamwi | 1964 | 48 kg + 2.7 kg/inch over 5 ft | 45.5 kg + 2.2 kg/inch over 5 ft |
Devine is the most widely used in clinical and pharmacy settings today, and is the formula most calculators default to. For a person under 5 feet tall, most formulas subtract the per-inch amount instead of adding it — resulting in a lower base estimate.
Stand fully upright without shoes against a wall, and measure in centimetres or feet/inches.
Subtract 60 inches (5 feet) from your total height in inches. This is the number the formula multiplies.
Use the Devine base — 50 kg for men, 45.5 kg for women — as your starting point.
Multiply the inches over 5 feet by 2.3 kg and add to the base weight.
Compare the result against a healthy BMI range (ICMR: 18.5–22.9) for your height to confirm it's a sensible target.
Take Priya, a 5'4" (64 inches) woman in Bengaluru, who wants to check her ideal weight range using multiple formulas.
| Formula | Calculation | Result |
|---|---|---|
| Devine | 45.5 + (2.3 × 4) | 54.7 kg |
| Robinson | 49 + (1.7 × 4) | 55.8 kg |
| Miller | 53.1 + (1.36 × 4) | 58.5 kg |
| Hamwi | 45.5 + (2.2 × 4) | 54.3 kg |
Priya's ideal weight range spans roughly 54–59 kg depending on the formula used. Her healthy BMI range (18.5–22.9 at 5'4") works out to approximately 47–60 kg — the ideal weight estimates comfortably fall inside this broader healthy zone, confirming the numbers are reasonable. Try ToolLoom's Ideal Weight Calculator to get all four formulas plus your BMI range instantly.
Approximate Devine-formula ideal weight ranges by common Indian adult heights, shown alongside the ICMR healthy BMI-based range for comparison:
| Height | Men — Ideal Weight | Women — Ideal Weight | ICMR Healthy BMI Range |
|---|---|---|---|
| 4'10" (147 cm) | 42.8 kg | 38.3 kg | 40–49 kg |
| 5'0" (152 cm) | 50.0 kg | 45.5 kg | 43–53 kg |
| 5'2" (157 cm) | 54.6 kg | 50.1 kg | 46–56 kg |
| 5'4" (163 cm) | 59.2 kg | 54.7 kg | 49–61 kg |
| 5'6" (168 cm) | 63.8 kg | 59.3 kg | 52–65 kg |
| 5'8" (173 cm) | 68.4 kg | 63.9 kg | 55–68 kg |
| 5'10" (178 cm) | 73.0 kg | 68.5 kg | 59–73 kg |
| 6'0" (183 cm) | 77.6 kg | 73.1 kg | 62–77 kg |
These are averages for reference only. Frame size (small/medium/large), muscle mass, and age all shift what's realistically healthy for an individual. Athletes and heavily muscled individuals routinely fall above their "ideal weight" while being in excellent health.
Both approaches use only height and weight, but they answer slightly different questions. Ideal weight formulas output a single target weight for your height. BMI (Body Mass Index) instead classifies your current weight into a category — underweight, healthy, overweight, or obese — using the formula weight (kg) ÷ height (m)².
For most adults of average build, the two approaches agree closely. They diverge most for people with high muscle mass (BMI can overestimate "overweight" for muscular people) or for older adults with reduced muscle mass (BMI can miss "healthy-looking" numbers that still carry higher body fat risk).
ToolLoom's BMI Calculator uses ICMR's Indian-specific thresholds (18.5–22.9 for healthy, 23+ for overweight) rather than the WHO's global 18.5–24.9 range, since South Asians statistically develop diabetes and heart disease risk at lower BMI values. Use both tools together for a fuller picture.