The Hamwi Formula: How to Calculate Your Ideal Body Weight
What the Hamwi formula is, how it works, and how to calculate your ideal body weight using it. Includes worked examples for men and women plus comparison with other methods.
The Hamwi formula estimates ideal body weight based on height. For men, it starts at 48 kg for the first 152.4 cm (5 feet) and adds 2.7 kg for each additional 2.54 cm (1 inch). For women, it starts at 45.5 kg for 152.4 cm and adds 2.2 kg per additional inch. A man who is 178 cm (5’10”) tall has a Hamwi ideal weight of approximately 73.5 kg (11 st 8 lb).
Calculate yours instantly with our Ideal Weight Calculator, which uses the Hamwi formula alongside three other established methods.
The Hamwi Formula
For men:
Ideal weight (kg) = 48 + 2.7 × (height in cm − 152.4) ÷ 2.54For women:
Ideal weight (kg) = 45.5 + 2.2 × (height in cm − 152.4) ÷ 2.54Worked Examples
Man, 178 cm (5’10”)
Inches above 5 feet = (178 − 152.4) ÷ 2.54 = 10.08 inches
Ideal weight = 48 + (2.7 × 10.08) = 48 + 27.2 = 75.2 kg
Woman, 165 cm (5’5”)
Inches above 5 feet = (165 − 152.4) ÷ 2.54 = 4.96 inches
Ideal weight = 45.5 + (2.2 × 4.96) = 45.5 + 10.9 = 56.4 kg
Quick Reference Table
| Height | Hamwi ideal weight (men) | Hamwi ideal weight (women) |
|---|---|---|
| 160 cm (5’3”) | 56.1 kg | 52.1 kg |
| 165 cm (5’5”) | 59.5 kg | 56.4 kg |
| 170 cm (5’7”) | 66.8 kg | 58.6 kg |
| 175 cm (5’9”) | 72.2 kg | 62.8 kg |
| 178 cm (5’10”) | 75.2 kg | 65.0 kg |
| 183 cm (6’0”) | 81.6 kg | 69.4 kg |
| 188 cm (6’2”) | 88.0 kg | 73.8 kg |
How Hamwi Compares to Other Formulas
The Hamwi formula (1964) is one of four commonly used ideal weight equations. Each gives slightly different results:
| Formula | Year | Man 178 cm | Woman 165 cm |
|---|---|---|---|
| Hamwi | 1964 | 75.2 kg | 56.4 kg |
| Devine | 1974 | 73.5 kg | 57.5 kg |
| Robinson | 1983 | 72.6 kg | 56.2 kg |
| Miller | 1983 | 71.5 kg | 57.4 kg |
No single formula is definitively correct. They are all rough guides originally developed for pharmaceutical dosing calculations, not comprehensive health assessments.
Limitations
The Hamwi formula does not account for body composition, frame size, age, or ethnicity. A muscular person may weigh well above their Hamwi ideal weight while being perfectly healthy. Use it as a starting reference point, not a target.
For a fuller picture, check your BMI alongside your ideal weight, and use our Body Fat Calculator if you want an estimate of your body composition.
Related Tools
- Ideal Weight Calculator — Hamwi, Devine, Robinson, and Miller formulas
- BMI Calculator — check your weight classification
- Calorie Calculator — find your daily maintenance calories