Ideal Weight Calculator
See your ideal body weight estimated by four classic formulas — Robinson, Miller, Devine and Hamwi — alongside the healthy weight range for your height, in metric or imperial units.
What “ideal body weight” really means
“Ideal body weight” (IBW) is a rough reference figure estimated mostly from your height, originally devised in clinical settings — for example to help with medication dosing — rather than as a personal goal. Several formulas exist, and they deliberately disagree by a few kilograms, which is the first clue that there is no single perfect number. A far more useful way to think about it is a healthy range: any weight that keeps you in the healthy BMI band (18.5–24.9) for your height is reasonable.
What IBW does well is give you a sensible starting reference. What it can’t do is tell you whether your weight is healthy, because it ignores muscle, frame size and body composition entirely. A muscular person can sit well above their “ideal” weight and be perfectly healthy. Treat the result as a conversation starter, not a verdict.
How to use this calculator
Enter your height and sex and the calculator shows your ideal body weight by four classic formulas plus their average, alongside the weight range that would put you in the healthy BMI band for your height. The four results form a small spread — use the span, not a single figure, as your reference. If you’re working toward a weight goal, the healthy BMI range is usually the more practical target, and our BMI calculator shows where your current weight sits.
How it’s calculated
All four formulas share the same shape: they set a base weight at a height of 5 feet (152 cm) and add a fixed amount for each inch above that, with a higher base for men than women. In words:
- Devine (1974): men 50 kg + 2.3 kg per inch over 5 ft; women 45.5 kg + 2.3 kg per inch. The original dosing formula.
- Robinson (1983): men 52 kg + 1.9 kg per inch; women 49 kg + 1.7 kg per inch. A refinement of Devine.
- Miller (1983): men 56.2 kg + 1.41 kg per inch; women 53.1 kg + 1.36 kg per inch.
- Hamwi (1964): men 48 kg + 2.7 kg per inch; women 45.5 kg + 2.2 kg per inch.
Because the per-inch increments differ, the formulas drift apart as height increases — which is exactly why showing the range is more honest than picking one.
A worked example
For a man who is 178 cm tall (5 ft 10 in, so 10 inches over 5 ft), the formulas give roughly: Devine 73 kg, Robinson 71 kg, Miller 70 kg and Hamwi 75 kg — an average near 72 kg. Meanwhile a healthy BMI for that height spans about 59–79 kg. So the “ideal” figure lands comfortably inside a much wider healthy range, underlining that it’s a midpoint reference rather than a strict goal.
The four formulas at a glance
| Formula | Year | Originally designed for |
|---|---|---|
| Hamwi | 1964 | Quick clinical estimates |
| Devine | 1974 | Medication dosing |
| Robinson | 1983 | Refining Devine’s figures |
| Miller | 1983 | Alternative refinement |
Limitations & tips
The biggest limitation is what these formulas leave out: they use only height and sex, so they can’t account for a larger or smaller frame, the extra weight of a muscular build, or differences in body composition. They also weren’t designed as wellness goals — Devine’s formula, for instance, exists to help calculate drug doses. They may misjudge very short or very tall people, older adults who have lost muscle, and athletes. Use your result as a starting reference, lean on the healthy weight range rather than a single figure, and set any actual weight goal with a healthcare professional who can factor in your build, health history and lifestyle.
Frequently asked questions
How is ideal weight calculated?
These formulas estimate ideal weight from height and sex. Each starts from a base weight at 5 feet (152 cm) and adds a set amount per inch above that. We show all four results plus their average.
Which ideal weight formula is best?
There's no single best one — they were derived for different purposes and give a range. For most people the healthy BMI range (18.5–24.9) is a more practical target than any single number.
Do these formulas account for muscle?
No. Like BMI, they use only height and sex, so athletes and very muscular people may sit above their 'ideal' weight while being perfectly healthy. Use them as a guide, not a rule.
Why do the four formulas give different numbers?
They were created at different times and for different purposes, and each adds a slightly different amount of weight per inch of height above 5 feet. That’s why the results spread apart, especially for taller people. The spread is a feature, not an error — it reminds you that “ideal weight” is a range, not a single exact figure.
Should I try to reach my exact ideal weight?
Not as a strict target. These numbers are reference points, and a healthy weight is better thought of as a range — for most people the weights that fall in the healthy BMI band for their height. Chasing a precise figure can be counterproductive; sustainable habits matter far more than hitting one number.
Does frame size change my ideal weight?
Yes, in practice. Someone with a broad, large frame naturally carries more bone and muscle and will sit higher than someone of the same height with a small frame, yet the formulas don’t adjust for this. If your wrist and joints are notably large or small, expect your healthy weight to land toward the upper or lower end of the range.
Is ideal weight the same for men and women?
No. Each formula uses a lower base weight for women than men at the same height, reflecting average differences in build and body composition. Even so, the formulas still ignore individual muscle and frame, so the male/female split is just an average, not a rule for any specific person.
Sources & references
- CDC — Adult BMI Categories — the healthy BMI band (18.5–24.9) this calculator uses for its "healthy weight range."
- "Universal equation for estimating ideal body weight and body weight at any BMI" (PMC, National Institutes of Health) — a review of the classic Devine, Hamwi, Robinson and Miller formulas used in this tool, and their limitations.
Last updated: July 2026 · How we calculate
BriskToolbox provides estimates for general information only and is not medical advice. Talk to a healthcare professional about your individual health.