For educational and tracking purposes only. Results are estimates and are not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional.
Calculator tool
How this calculator works
Use the explanation to understand the formula, assumptions, and practical limits behind the calculator result.
The Three Reference Formulas
Ideal body weight (IBW) formulas are reference equations that are often used in clinical contexts such as dosing and ventilation, but they are not direct measures of personal health or body composition. They use height above 5 feet (60 inches) as the primary input.
Devine Formula (1974) — Most widely cited in clinical practice:
Robinson Formula (1983):
Miller Formula (1983):
- All results are in kilograms
- Formulas apply to heights above 5 feet; below 5 feet, adjustments are needed
Worked Example — 5 ft 9 in (69 inches) Male
Height above 5 ft = 69 − 60 = 9 inches
| Formula | Calculation | Result |
|---|---|---|
| Devine | 50 + 2.3 × 9 | 70.7 kg (155.8 lb) |
| Robinson | 52 + 1.9 × 9 | 69.1 kg (152.3 lb) |
| Miller | 56.2 + 1.41 × 9 | 68.9 kg (151.9 lb) |
| Range | 68.9 – 70.7 kg |
Frame Size and the Range
Bone structure affects how much weight a given height can carry healthily. Frame size can be estimated from wrist circumference (for the same height, larger wrists indicate larger frames):
- Small frame: aim toward the lower end of the IBW range
- Medium frame: middle of the range
- Large frame: upper end or slightly above
Note: these formulas have a ±5–10 kg error margin. Body composition (muscle vs fat) matters more than weight alone for health outcomes.
Frequently asked questions
Why do the three formulas give slightly different results?
Devine, Robinson, and Miller use different coefficients after 5 feet of height, so they produce nearby but not identical estimates. The variation is a reminder that ideal body weight is a reference construct, not one exact personal target.
Is the ideal weight from these formulas the same as a healthy weight?
No. These formulas are rough reference equations and were not designed to diagnose whether one individual is healthy. A healthier interpretation also considers BMI context, waist circumference, body composition, medical history, and clinician guidance.
How do I estimate my frame size?
The frame setting in this tool shifts the displayed range modestly to make comparisons easier, but it is only a heuristic. It does not replace body-composition assessment or clinical judgment.
Should athletes use these formulas for weight goals?
Use the range as one reference point when comparing with BMI, body-fat percentage, or a clinician's goal. Do not treat a single number as proof that weight is healthy or unhealthy by itself.
