Ideal Weight Calculator
What Is Ideal Weight?
Ideal weight is a long-standing shorthand for the weight at which a person of a given height and sex is statistically most likely to be healthy. It is not a single magic number handed down by nature: it comes from formulas developed by doctors and researchers, most famously by Robinson, Devine and Miller, who related height to a reference weight for use in medicine — for example, when working out drug doses. Today people use the same figures as a sensible target range when setting weight goals, alongside the better-known body mass index.
It is important to treat the result as a guide, not a verdict. Muscle mass, bone density, age, frame size and ethnicity all affect what a healthy weight looks like for an individual, and two people of the same height can be perfectly healthy at quite different weights. That is why this calculator shows three classic formulas plus your full healthy BMI range: together they give you a zone to aim for, rather than one number to obsess over. Use it as a starting point for a conversation with yourself — and, if you have health concerns, with a clinician too.
How to Use This Ideal Weight Calculator
- Choose your units. Tap Metric to enter height in centimetres and see results in kilograms, or Imperial for inches and pounds.
- Select your gender. The formulas differ for men and women, because average body composition differs between the sexes.
- Enter your height. Measure barefoot, standing straight with your back against a wall, from floor to the top of your head. In Imperial mode, enter your total height in inches — for example, 5 feet 10 inches is 70 inches.
- Click Calculate My Ideal Weight. You will see the Robinson estimate as the headline figure, with Devine and Miller estimates and your healthy BMI weight range underneath.
- Read the range, not just the headline. If the three formulas span a few kilograms, that spread is honest: your healthy zone is a range, and anywhere inside the BMI range is a reasonable place to be.
Worked Example: Man, 178 cm Tall
Take a man who is 178 cm tall — about 5 feet 10 inches, or 70.1 inches. Here is exactly what the calculator does:
- Inches over 5 feet: 70.1 − 60 = 10.1 inches
- Robinson: 52 + (1.9 × 10.1) = 71.1 kg
- Devine: 50 + (2.3 × 10.1) = 73.2 kg
- Miller: 56.2 + (1.41 × 10.1) = 70.4 kg
- Healthy BMI range: 18.5 × 1.78² = 58.6 kg, and 24.9 × 1.78² = 78.9 kg, so 58.6 – 78.9 kg
All three formulas cluster around 70–73 kg, comfortably inside the healthy BMI range of 58.6–78.9 kg. That agreement is reassuring: for this height, a weight in the low seventies is a very sensible target, while anything from the high fifties to the high seventies still counts as healthy by BMI. Try your own height in the tool above and see how the formulas compare for you.
How the Three Formulas Differ
| Formula | Men | Women |
|---|---|---|
| Robinson (1983) | 52 kg + 1.9 kg per inch over 5 ft | 49 kg + 1.7 kg per inch over 5 ft |
| Devine (1974) | 50 kg + 2.3 kg per inch over 5 ft | 45.5 kg + 2.3 kg per inch over 5 ft |
| Miller (1983) | 56.2 kg + 1.41 kg per inch over 5 ft | 53.1 kg + 1.36 kg per inch over 5 ft |
Tips for Reaching Your Ideal Weight
- Aim for the range, not a single kilogram. Landing anywhere in your healthy BMI range is a win; chasing one exact number adds stress without adding health.
- Change slowly. Losing or gaining about half a kilogram a week is sustainable, protects muscle, and is far more likely to last than a crash approach.
- Pair the scale with a tape measure. Waist size and how your clothes fit often improve before the scale moves, especially if you are exercising.
- Keep strength in the plan. Resistance training twice a week helps ensure weight lost is fat, not muscle, and keeps your metabolism healthier as you age.
- Check in monthly. Weigh yourself under the same conditions each month and adjust food and activity gradually, rather than reacting to daily ups and downs.
Frequently Asked Questions
What is the most accurate ideal weight formula?
No single formula is definitively best — Robinson, Devine and Miller usually agree within a few kilograms. Robinson is the most commonly cited for general use, which is why it is the headline figure here, but the healthy BMI range is arguably the more useful guide because it gives you a zone rather than a point.
Is ideal weight the same as a healthy weight?
Not exactly. Ideal weight is a formula estimate for one reference weight at your height, while a healthy weight is a range — the BMI range of 18.5 to 24.9. Most health professionals prefer the range, since healthy bodies vary in frame, muscle and build.
Does ideal weight account for muscle mass?
No, and that is its main limitation. A very muscular person can weigh more than their ideal weight while carrying little body fat. If you train with weights regularly, use body fat percentage and waist measurement alongside this calculator rather than relying on weight alone.
What if I am shorter than 5 feet?
The formulas still work: the per-inch amount is subtracted for each inch under 5 feet instead of added. For example, a man 4 feet 10 inches tall (58 inches) would have a Robinson ideal of 52 minus 1.9 times 2, which is 48.2 kg. The calculator handles this automatically.
Should children use this calculator?
No. Children's healthy weights depend on age and sex as well as height, and are assessed with growth charts by a paediatrician. This calculator is for adults only.