Ideal Weight Calculator
Calculate ideal body weight using four established formulas: Devine, Robinson, Miller, and Hamwi.
"What should I weigh?" is one of the most common health questions, and there is no single perfect answer — but several well-established formulas give a sensible target range based on your height and sex. This calculator runs the classic Devine, Robinson, and Miller equations side by side so you can see a realistic band rather than a single, falsely precise number.
These formulas were originally developed for medical purposes, such as dosing medication, and have since become a popular reference for a healthy goal weight. Because they each weight height slightly differently, seeing all three at once is more useful than any one alone: the spread between them is itself the message — that ideal weight is a range, not a fixed point, and that your frame size, muscle mass, and overall health matter just as much as the scale.
Plug in some numbers —
we'll crunch.
How to use
- 1Select your biological sex.
- 2Enter your height in centimetres.
- 3Choose whether to see results in kg or lbs.
- 4Compare four different formula results and the average.
How it works
Each formula starts from a base weight for a person of about 5 feet (152 cm) tall and adds a set amount for every inch above that. The Devine formula (1974), the most widely used, adds 2.3 kg per inch over 5 feet to a base of 50 kg for men and 45.5 kg for women. The Robinson (1983) and Miller (1983) formulas use slightly different bases and per-inch increments, which is why they produce a small range rather than identical answers.
All three depend only on height and sex, so like BMI they cannot account for body composition or frame size. They are best read as the center of a healthy band: a person with a larger frame or more muscle may sensibly sit above the figure, while someone with a slight build may sit below it. The goal is a reasonable target zone, not a number to hit exactly.
Worked examples
A typical male estimate
A man who is 180 cm (about 5 ft 11 in) tall.
- That is roughly 11 inches over 5 feet.
- Devine: 50 + (2.3 × 11) ≈ 75.3 kg.
- Robinson and Miller land slightly lower, near 72–74 kg.
His ideal-weight range across the three formulas is roughly 72–76 kg. Any point in that band is a reasonable, healthy target depending on his frame and muscle mass.
Reading the spread for a woman
A woman who is 165 cm (about 5 ft 5 in) tall.
- About 5 inches over 5 feet.
- Devine: 45.5 + (2.3 × 5) ≈ 57 kg.
- Miller tends to read a few kg lower.
The formulas suggest roughly 54–58 kg. Rather than fixating on one figure, she can treat the whole range as healthy and let how she looks, feels, and performs fine-tune the target.
Tips & common mistakes
Read the output as a range, not a target. The whole point of showing three formulas is that 'ideal weight' is inherently fuzzy — anywhere within the band the equations produce is reasonable, and a few kilograms either side rarely matters for health. Fixating on hitting one exact number is a recipe for frustration.
These formulas ignore muscle and frame size, so they systematically under-shoot for muscular or large-framed people. A fit, athletic person may healthily weigh well above their 'ideal' figure because muscle is dense. If you lift weights or have a broad build, weigh the result against how you look and feel, and consider body fat percentage as a better guide.
Use ideal weight as a rough compass, not a strict destination — overall health depends far more on fitness, nutrition, sleep, and body composition than on landing on a specific weight. If you are setting a weight goal for medical reasons, do it with a doctor who can factor in your full health picture. This tool provides general estimates for education only and is not medical advice.
Frequently asked questions
⚠ Ideal weight formulas are estimates. Healthy weight depends on many factors including muscle mass, bone density, and individual health history.
Last reviewed: June 2026
About this calculator
Calculate ideal body weight using four established formulas: Devine, Robinson, Miller, and Hamwi.