Calcustack

Ideal Weight Calculator

Get a healthy weight range using BMI plus the classic Devine and Robinson formulas. Useful as a sanity check, not a verdict.

Units

Your healthy weight range

128.9 lb – 173.5 lbbased on healthy BMI (18.5-24.9)
Devine
160.9 lb
Robinson
156.5 lb
BMI low
128.9 lb
BMI high
173.5 lb

Worked examples

How "ideal weight" is calculated

There is no single ideal weight number. This calculator gives you three lenses, and the truth lives somewhere among them:

  • Healthy BMI range (18.5-24.9): the broadest population-level bracket recommended by the WHO. weight(kg) = BMI × height(m)²
  • Devine formula (1974): originally created for calculating medication dosages. Men: 50 + 2.3 kg × inches over 5 ft. Women: 45.5 + 2.3 kg × inches over 5 ft.
  • Robinson formula (1983): a tighter, more modern variant. Men: 52 + 1.9 kg × inches over 5 ft. Women: 49 + 1.7 kg × inches over 5 ft.

How to use the result

Treat the BMI range as your bracket and the Devine / Robinson numbers as anchor points within it. If you carry significant muscle, you'll naturally sit toward the top of the range or even above , that's expected and not unhealthy. If your weight is well outside the bracket in either direction, that's worth a conversation with a doctor or dietitian.

Combine this with the body fat calculator and the lean body mass calculator for a more complete picture than weight alone can give you.

Worked examples

Example 1. 178 cm man. BMI range: 58.6-78.9 kg. Devine: 75 kg. Robinson: 68.5 kg. A reasonable target is somewhere in the middle of that range, adjusted up if he carries muscle.

Example 2. 165 cm woman. BMI range: 50.4-67.8 kg. Devine: 56.95 kg. Robinson: 54.4 kg. Athletic women routinely sit at the top of this range.

Example 3. 190 cm man. BMI range: 66.8-89.9 kg. Devine: 86 kg. Robinson: 74.7 kg. A 190 cm lifter at 95 kg / 12% body fat is healthier than the BMI label suggests.

Common mistakes

  • Treating it as a verdict. It's a bracket, not a target.
  • Ignoring body composition. Muscle, fat distribution and ethnicity all matter.
  • Aiming for the low end without good reason. Lower isn't better past a point.
  • Applying it to athletes, kids, pregnant women, or the elderly. BMI doesn't fit any of those well.

FAQ

Is there one 'ideal' weight?+

No. 'Ideal weight' is a useful range, not a single number. Body composition, frame size, training status and ethnicity all shift what's healthy for you personally.

Which formula is most accurate?+

None is definitive. The healthy BMI range (18.5-24.9) is the broadest evidence-based bracket. Devine and Robinson are older clinical formulas mostly used for medication dosing.

Why does my muscular build show as 'overweight'?+

BMI doesn't account for muscle mass. A 200 lb lifter at 12% body fat is technically 'overweight' by BMI but obviously not unhealthy. Use body fat percentage instead for athletes.

Is BMI useful at all?+

For the average sedentary adult, yes. For trained athletes, pregnant women, the elderly, and children, no. Use it as one signal, not the only one.

Should I aim for the low or high end of the range?+

Most people feel and perform best near the middle. Going under the low end usually requires sustained underfeeding that hurts hormones, sleep and lifts.

What about ethnicity?+

Population studies show that healthy BMI ranges are slightly lower for some Asian populations and slightly higher for some Pacific Islander populations. Treat the global numbers as a starting bracket.

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