Ideal Weight Calculator
Calculate your ideal weight using four validated clinical formulas. Understand what each result means, why they differ, and how to use them alongside the BMI healthy weight range.
Enter your values above to see the results.
Tips & Notes
- ✓The four ideal weight formulas typically agree within 5–8 kg of each other. If your current weight falls within that range, you are likely at or near any reasonable reference target.
- ✓These formulas were not designed for people under 5 feet tall (152 cm) — accuracy drops significantly below that height as the base values dominate.
- ✓Frame size matters. A large-framed person with broad shoulders and wide hips may healthily weigh 5–10% above these estimates; a small-framed person may be healthiest 5% below.
- ✓For athletes and people with significant muscle mass, the BMI healthy weight range (upper end) is a more realistic target than the single-point formula estimates.
- ✓None of these formulas account for body fat percentage. A person at the "ideal weight" with 35% body fat is not in ideal health; a person 10 kg above ideal weight with 14% body fat likely is.
Common Mistakes
- ✗Treating the formula result as a precise personal goal rather than a rough clinical reference point designed for medication dosing.
- ✗Using these formulas for people under 5 feet tall, where the math produces results that do not scale properly.
- ✗Ignoring the BMI healthy weight range (18.5–24.9), which is a broader, more realistic, and better-validated target for general health.
- ✗Assuming that weighing more than the formula result means you are unhealthy — athletes, muscular individuals, and large-framed people routinely exceed these estimates in perfect health.
- ✗Comparing formula results across different calculators without checking which formula each is using — Hamwi and Robinson can differ by 6 kg at the same height.
Ideal Weight Calculator Overview
Ideal body weight formulas give clinicians a quick estimate of lean-based weight for drug dosing and nutritional planning. For everyone else, they provide a ballpark reference — useful as context, not as a target.
Devine and Robinson formulas (most widely used clinically):
Devine Formula (most widely used clinically): Male: IBW = 50 kg + 2.3 kg × (height in inches − 60) Female: IBW = 45.5 kg + 2.3 kg × (height in inches − 60) Robinson Formula: Male: IBW = 52 kg + 1.9 kg × (height in inches − 60) Female: IBW = 49 kg + 1.7 kg × (height in inches − 60)
EX: Male, 5 ft 10 in (70 inches = 10 inches over 5 ft) Devine: 50 + 2.3 × 10 = 73.0 kg (160.9 lbs) Robinson: 52 + 1.9 × 10 = 71.0 kg (156.5 lbs) Miller: 56.2 + 1.41 × 10 = 70.3 kg (155.0 lbs) Hamwi: 48 + 2.7 × 10 = 75.0 kg (165.3 lbs) BMI healthy range (18.5–24.9): 57.9–78.0 kg
Miller and Hamwi formulas:
Miller Formula: Male: IBW = 56.2 kg + 1.41 kg × (height in inches − 60) Female: IBW = 53.1 kg + 1.36 kg × (height in inches − 60) Hamwi Formula: Male: IBW = 48 kg + 2.7 kg × (height in inches − 60) Female: IBW = 45.4 kg + 2.3 kg × (height in inches − 60)
EX: Female, 5 ft 5 in (65 inches = 5 inches over 5 ft) Devine: 45.5 + 2.3 × 5 = 57.0 kg (125.7 lbs) Robinson: 49 + 1.7 × 5 = 57.5 kg (126.8 lbs) Miller: 53.1 + 1.36 × 5 = 59.9 kg (132.1 lbs) Hamwi: 45.4 + 2.3 × 5 = 56.9 kg (125.4 lbs) BMI healthy range: 51.8–69.7 kg — the formulas fall right in the middle.
Ideal weight formula comparison across common heights:
| Formula | Year | Originally developed for | Male base (at 5 ft) | Female base (at 5 ft) |
|---|---|---|---|---|
| Hamwi | 1964 | Diabetes nutritional planning | 48 kg | 45.4 kg |
| Devine | 1974 | Gentamicin antibiotic dosing | 50 kg | 45.5 kg |
| Robinson | 1983 | Pulmonary drug dosing | 52 kg | 49 kg |
| Miller | 1983 | Obesity research comparison | 56.2 kg | 53.1 kg |
When each formula is most appropriate:
| Height | Devine IBW (M) | Devine IBW (F) | BMI Healthy Range |
|---|---|---|---|
| 5 ft 0 in (152 cm) | 50.0 kg | 45.5 kg | 42.8–57.7 kg |
| 5 ft 4 in (163 cm) | 59.2 kg | 54.7 kg | 49.2–66.2 kg |
| 5 ft 8 in (173 cm) | 68.5 kg | 64.0 kg | 55.5–74.7 kg |
| 5 ft 10 in (178 cm) | 73.0 kg | 68.5 kg | 58.7–79.0 kg |
| 6 ft 0 in (183 cm) | 77.6 kg | 73.0 kg | 62.0–83.5 kg |
| 6 ft 2 in (188 cm) | 82.1 kg | 77.6 kg | 65.3–87.9 kg |
The formulas consistently produce a single point estimate, while the BMI range gives a 15–20 kg window. For practical purposes, the BMI healthy weight range (18.5–24.9) is a more honest and clinically useful target for most people because it acknowledges that healthy bodies come in a real range of sizes. The clinical formulas remain most relevant in their original context — drug dosing and clinical nutrition — and as a rough check that your weight goal is in a reasonable vicinity. If a formula says 70 kg and you want to weigh 68 or 73 kg, both are well within the healthy range. The formula is not a verdict.
Frequently Asked Questions
Each formula was derived from a different clinical dataset and designed for a different purpose. Devine (1974) was based on gentamicin dosing research, Robinson (1983) on pulmonary patients, Hamwi (1964) on diabetic nutrition planning, and Miller (1983) on obesity research. The populations studied, the statistical methods, and the clinical goals all differed, producing slightly different slope and intercept values. None was derived to define personal weight goals — they were all proxies for estimating lean tissue mass in hospitalized patients.
No single formula is universally most accurate for general use. Devine is the most widely cited in clinical literature and is commonly used in ICU settings. Robinson tends to produce more conservative estimates. For practical purposes, the average of all four provides a reasonable midpoint. However, the BMI healthy weight range (18.5–24.9) is arguably more useful for most people because it acknowledges natural variation in body size rather than targeting a single point estimate.
Yes. These formulas use a linear relationship per inch above 5 feet, which means they work well in the average height range but break down at extremes. Very tall people (above 6 ft 4 in) will have the formula generate ideal weights that imply unrealistically low BMI values. Very short people (below 5 ft) face the opposite problem — the base values of the formulas are designed for the 5-foot starting point. For people outside the 5 ft to 6 ft 2 in range, the BMI method (targeting BMI 20–23) often gives a more reasonable result.
The formulas themselves do not change with age, but the practical interpretation does. Research on older adults (65+) suggests that slightly higher weight — and therefore higher BMI in the 25–27 range — is associated with better health outcomes than being at the lower end of the normal range. This is thought to reflect the protective reserve that additional weight provides during illness, hospitalization, or stress. The formula results, which often fall in the BMI 20–23 range, may therefore be too low as a target for adults over 65.
Being significantly below ideal weight by these formulas typically means your BMI is below 18.5 — the underweight classification. This is associated with reduced muscle and bone mass, immune compromise, hormonal disruption, nutrient deficiencies, and in severe cases, cardiac complications. If you are well below these estimates and have not intentionally lost weight, it warrants medical evaluation. If you are underweight due to restrictive eating, working with a registered dietitian is strongly recommended before attempting rapid weight gain.
Calorie needs (TDEE) are most accurately calculated from your current weight and body composition, not your ideal weight. Using ideal weight to calculate calories will underestimate your needs if you currently weigh significantly more — your body has to fuel its actual size, not your target size. The correct approach is: calculate TDEE based on current weight, apply a moderate deficit (300–500 kcal/day), and adjust as you progress. As your weight decreases toward your target, your TDEE will decrease accordingly.