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Step by step
Here is the exact math behind your result, using your own numbers.
- Convert stones to pounds. There are 14 pounds in a stone: 11 st 2 lb = 154 + 2 = 156 lb.
- Convert height to inches. 5 ft 4 in = 64 in.
- Square the height. 64 × 64 = 4,096.
- Multiply weight by 703 and divide. 156 × 703 = 109,668, and 109,668 ÷ 4,096 = 26.77, which rounds to 26.8.
The metric route
Many UK scales and GP records use kilograms and centimeters. One stone is 6.35 kg, so you can also convert and use the metric formula:
156 lb = 70.8 kg, 5 ft 4 in = 162.6 cm, and 70.8 ÷ 1.626² = 26.8
Both routes give the same BMI. How to calculate BMI in cm and kg.
Stones to pounds and kilograms
| Stones | Pounds | Kilograms |
|---|---|---|
| 8 st | 112 lb | 50.8 kg |
| 9 st | 126 lb | 57.2 kg |
| 10 st | 140 lb | 63.5 kg |
| 11 st | 154 lb | 69.9 kg |
| 12 st | 168 lb | 76.2 kg |
| 14 st | 196 lb | 88.9 kg |
| 16 st | 224 lb | 101.6 kg |
Common mistakes
- Writing 11 st 2 lb as 11.2 stones. 2 lb is 0.14 of a stone, so it's 11.14 stones, not 11.2.
- Converting stones straight to kg with the wrong factor. 1 st = 6.35 kg (14 × 0.4536).
- Mixing a metric height with the 703 formula. Use inches with pounds, or centimeters with kilograms.
Frequently asked questions
Sources
Kept up to dateLast updated October 9, 2026
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This page is for education and is not medical advice. Talk with a healthcare professional about your weight and health.
