# Free online ideal body weight calculator

> Ideal body weight (IBW) is a height-based estimate of a healthy target weight. This calculator runs four widely cited formulas and shows you where they agree — and where they.

Find your ideal body weight using four evidence-based formulas — Devine, Robinson, Miller, and Hamwi. See the average, the full range, and a side-by-side formula comparison.

**Interactive version:** https://onlinecalculator.me/health/ideal-weight/
**Category:** Health

## How to use

1. Select sex and unit system with the toggles.
2. Enter your height in inches or centimeters.
3. The average ideal weight and the range across all four formulas appear instantly.
4. The formula breakdown shows each result individually.

## The four formulas

All formulas compute weight from height above 5 feet (60 inches). Heights below 5 ft extrapolate backward from the base values.

**Devine (1974):**
```
Men:   50 kg + 2.3 kg per inch over 60 in
Women: 45.5 kg + 2.3 kg per inch over 60 in
```

**Robinson (1983):**
```
Men:   52 kg + 1.9 kg per inch over 60 in
Women: 49 kg + 1.7 kg per inch over 60 in
```

**Miller (1983):**
```
Men:   56.2 kg + 1.41 kg per inch over 60 in
Women: 53.1 kg + 1.36 kg per inch over 60 in
```

**Hamwi (1964) — originally in pounds:**
```
Men:   106 lb + 6 lb per inch over 60 in
Women: 100 lb + 5 lb per inch over 60 in
```

## Worked example

Male, 5 ft 7 in (67 in) — 7 inches above 5 ft:

| Formula   | Calculation                | Result |
|-----------|---------------------------|--------|
| Devine    | 50 + 2.3 × 7 = 66.1 kg   | 145.7 lb |
| Robinson  | 52 + 1.9 × 7 = 65.3 kg   | 143.9 lb |
| Miller    | 56.2 + 1.41 × 7 = 66.1 kg | 145.7 lb |
| Hamwi     | 106 + 6 × 7              | 148.0 lb |

Average ≈ **145.8 lb** (66.1 kg). Range: 143.9–148.0 lb.

## Notes

> **Health disclaimer:** Ideal body weight formulas are population-level estimates originally designed for clinical drug dosing, not personal fitness targets. They do not account for muscle mass, body composition, or age. Consult a healthcare professional before using IBW to set a weight goal.

- Sources: Devine BJ (1974) *Drug Intelligence and Clinical Pharmacy*; Robinson JD et al. (1983) *JPEN*; Miller DR et al. (1983) *Am J Hosp Pharm*; Hamwi GJ (1964) *Diabetes*.

## Frequently asked questions

### What is ideal body weight and how is it used?

Ideal body weight is a height-based estimate originally developed for clinical drug dosing — medications like gentamicin and vancomycin are dosed on IBW rather than total weight to avoid overdosing obese patients. It is also used as a rough fitness target, though it does not account for muscle mass, age, or body composition.

### Why do the four formulas give different numbers?

Each formula was developed independently from different study populations in different decades. Devine (1974) and Robinson (1983) were drug-dosing references; Miller (1983) and Hamwi (1964) came from clinical nutrition. They use slightly different base weights and per-inch increments, so results can differ by 5–15 lb for the same height.

### Should I use IBW as my personal weight goal?

Not necessarily. IBW formulas do not account for muscle mass, frame size, age, or body composition. A heavily muscled person may weigh well above IBW with very low body fat. Think of IBW as a clinical reference point, not a personal target. Pair it with BMI and body fat percentage for a fuller picture.

### Which formula is the most accurate?

No single formula is definitively best for the general population. Devine is the most widely used in clinical settings. Robinson and Miller tend to give slightly lower values. The average of the four formulas, or the range they span, is often a more useful reference than any single estimate.

### Can I share my results with a link?

Yes. Use the "Share with my numbers" button to copy a URL that encodes your height and sex as query parameters. Anyone who opens it will see the same inputs pre-filled.

## Sources

- [Variability in ideal body weight formulae](https://pmc.ncbi.nlm.nih.gov/articles/PMC10621523/) — Journal of the Intensive Care Society

## Related calculators

- [BMI calculator](https://onlinecalculator.me/health/bmi/) — Body mass index from height and weight with CDC healthy weight categories.
- [Body fat percentage calculator](https://onlinecalculator.me/health/body-fat/) — Estimate body fat using the US Navy circumference method — more nuanced than weight alone.
- [BMR calculator](https://onlinecalculator.me/health/bmr/) — Calculate basal metabolic rate — calories burned at rest — from age, sex, height, and weight.
- [Calorie calculator](https://onlinecalculator.me/health/calorie/) — Estimate daily calorie needs adjusted for activity level and weight goal.

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