BMI Calculator Using Stones and Pounds — UK Measurement Guide

How to Calculate BMI Using Stones and Pounds

In the UK, most people still weigh themselves in **stones and pounds** rather than kilograms — even though the NHS, doctors, and the WHO use metric units for BMI calculation. This article shows you exactly how to convert UK units into a BMI score, with worked examples and a full lookup table.

To skip the maths entirely, use our [free BMI calculator](/) — it accepts stones-and-pounds and feet-and-inches directly and converts everything for you.

The Standard BMI Formula (Metric)

The official WHO/NHS BMI formula uses metric units:

BMI = weight (kg) ÷ height (m)²

To use UK units, you need to convert your weight and height into metric first.

Converting Stones to Kilograms

There are **6.35029 kg** in 1 stone. The quick way to convert:

Quick reference

| Stones | Kilograms |

|---|---|

| 7 st | 44.5 kg |

| 8 st | 50.8 kg |

| 9 st | 57.2 kg |

| 10 st | 63.5 kg |

| 11 st | 69.9 kg |

| 12 st | 76.2 kg |

| 13 st | 82.6 kg |

| 14 st | 88.9 kg |

| 15 st | 95.3 kg |

| 16 st | 101.6 kg |

| 17 st | 108.0 kg |

| 18 st | 114.3 kg |

Converting Feet and Inches to Metres

There are **2.54 cm** in 1 inch. The quick way:

Quick reference

| Height | Metres |

|---|---|

| 4'10" | 1.47 m |

| 5'0" | 1.52 m |

| 5'2" | 1.57 m |

| 5'4" | 1.63 m |

| 5'6" | 1.68 m |

| 5'8" | 1.73 m |

| 5'10" | 1.78 m |

| 6'0" | 1.83 m |

| 6'2" | 1.88 m |

| 6'4" | 1.93 m |

Worked Example #1: 11 stone 5 pounds, 5'6"

Result: BMI 25.6 — just into the overweight category.

Worked Example #2: 14 stone 0 pounds, 5'10"

Result: BMI 28.1 — overweight, near the obese threshold.

NHS Healthy Weight Range in Stones

The NHS healthy weight range (BMI 18.5–24.9) translates to the following stones-and-pounds ranges by height:

| Height | Healthy weight (stones & pounds) |

|---|---|

| 4'10" (1.47 m) | 6 st 4 lb – 8 st 6 lb |

| 5'0" (1.52 m) | 6 st 10 lb – 9 st 0 lb |

| 5'2" (1.57 m) | 7 st 2 lb – 9 st 8 lb |

| 5'4" (1.63 m) | 7 st 8 lb – 10 st 3 lb |

| 5'6" (1.68 m) | 8 st 1 lb – 10 st 12 lb |

| 5'8" (1.73 m) | 8 st 8 lb – 11 st 7 lb |

| 5'10" (1.78 m) | 9 st 2 lb – 12 st 3 lb |

| 6'0" (1.83 m) | 9 st 9 lb – 12 st 13 lb |

| 6'2" (1.88 m) | 10 st 3 lb – 13 st 9 lb |

| 6'4" (1.93 m) | 10 st 11 lb – 14 st 6 lb |

If your weight in stones falls inside the range for your height, you're in the NHS healthy BMI band.

A Shortcut: Imperial BMI Formula

There is an imperial-units version of the BMI formula that skips the metric conversion:

BMI = (weight in pounds ÷ height in inches²) × 703

Convert your weight to pounds first: 1 stone = 14 pounds.

So 11 stone 5 lb = (11 × 14) + 5 = **159 lbs**.

For 5'6" = 66 inches.

BMI = (159 ÷ (66 × 66)) × 703 = (159 ÷ 4356) × 703 = 0.0365 × 703 = **25.7**.

(The tiny 0.1 difference from Example #1 is rounding.)

Targeting a Specific Weight in Stones

If you want to find what weight (in stones) you should aim for to reach a target BMI, use our [reverse BMI calculator](/reverse-bmi-calculator). It returns target weight in kilograms, pounds, **and** stones-and-pounds simultaneously.

Common UK Conversion Tips

A practical shortcut: to convert kg roughly to stones, divide by 6.35 (or divide by 6 then subtract a tiny amount). 80 kg ÷ 6.35 ≈ 12.6 stone (12 st 8 lb).

The Bottom Line

The NHS uses BMI for adults whether you weigh yourself in stones or kilograms — the underlying formula is the same. To work it out in UK units:

Or skip the maths and use our [free BMI calculator](/) — it accepts UK units directly and shows your result in all three weight units (kg, lbs, stones-and-pounds).