Ideal Weight Calculator
The ideal weight calculator estimates a healthy body weight for your height and gender using the Devine, Robinson, Miller and Hamwi formulas, plus the healthy BMI range.
verified_userReviewed by the Calculopedia editorial teamLast updated 2026-08-14
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quizExample
How this calculator works, with real numbers (no JavaScript needed):
Inputs
- Height
- 175
- Gender
- male
- Formula
- devine
Results
- Ideal body weight
- 70.5
- Healthy weight (lower)
- 56.7
- Healthy weight (upper)
- 76.3
functionsThe formula
Ideal body weight is a rough estimate of a healthy weight for your height. It's used in clinical settings (for example, to dose medications) and is handy as a reference — though it's an estimate, not a strict target.
Where these formulas came from
It may come as a surprise that "ideal weight" was never really meant as a lifestyle goal. The Devine formula (1974), the most widely used of the four, was originally devised to help clinicians calculate drug dosages — specifically aminoglycoside antibiotics for hospitalised patients — where a quick weight estimate based on height was more practical than measuring everyone. The Robinson, Miller and Hamwi formulas that followed were refinements of the same basic idea, each tuned slightly differently. In other words, these are clinical convenience tools, and the differences between them are exactly what you would expect from a rough estimate: they are not four separate truths about your health, but four flavourings of the same approximation.
The four formulas
All four formulas use a base weight for 5 feet (60 inches) of height, then add an allowance per extra inch:
| Formula | Male (base + per inch) | Female (base + per inch) |
|---|---|---|
| Devine | 50 kg + 2.3 kg | 45.5 kg + 2.3 kg |
| Robinson | 52 kg + 1.9 kg | 49 kg + 1.7 kg |
| Miller | 56.2 kg + 1.41 kg | 53.1 kg + 1.36 kg |
| Hamwi | 48 kg + 2.7 kg | 45.5 kg + 2.2 kg |
Worked example
A 175 cm (≈68.9 in) man using Devine:
Height above 5 ft = 68.9 − 60 = 8.9 inches
Ideal = 50 + 2.3 × 8.9 = 50 + 20.5 ≈ 70.5 kg
The calculator also shows the healthy BMI range (18.5–24.9) for your height — for 175 cm that's about 56.7–76.3 kg. The four formulas sit within that range but give slightly different answers; the differences show that "ideal" is fuzzy.
Why the answers differ
Notice how narrow the spread is in the equation: for a man, the four formulas give somewhere between roughly 57 kg (Miller) and 71 kg (Devine) depending on height — a meaningful gap that has nothing to do with your actual health and everything to do with how each formula's authors chose their base weight and per-inch allowance. That is a useful lesson: when two "authoritative" formulas disagree by several kilograms, no single weight can claim to be the ideal.
Use with care
These formulas were developed decades ago from limited samples and don't account for frame size or muscle mass. They are best understood as quick clinical references rather than personal verdicts. For most people the healthy BMI range is the more meaningful target — stay within it and focus on habits, not a single number. This tool is for general information and not a substitute for professional medical advice.
helpFrequently asked questions
question_markWhat is ideal body weight?
Ideal body weight is an estimate of a healthy weight for a given height and gender, calculated by formulas like Devine, Robinson, Miller and Hamwi.
question_markWhat is the Devine formula?
The Devine formula gives men 50 kg plus 2.3 kg per inch above 5 feet, and women 45.5 kg plus 2.3 kg per inch above 5 feet.
question_markWhich ideal weight formula is most accurate?
There's no single "most accurate" — the formulas were built from small, older samples. Treat the healthy BMI range as the practical target instead.