Stone to Pounds Calculator - Convert st to lb and kg

About the Stone to Pounds Calculator

In the United Kingdom and Ireland, people commonly give their body weight in stone and pounds — "eleven stone four", for example — even though shops, doctors and official forms now use kilograms. Americans, meanwhile, think in pounds alone. So a British weight often needs converting to pounds for an American fitness app, or to kilograms for a medical form, a gym programme or an airline.

This stone to pounds calculator converts stone, or stone and pounds together, into pounds and kilograms exactly. It also shows the weight in decimal stone and in stone and pounds tidied up, plus the total in ounces.

How to Use the Stone to Pounds Calculator

Enter the stone. Decimals such as 12.5 are fine.

Enter any extra pounds, as in 11 stone 4 pounds. Leave the pounds at zero if you only have stone.

The pounds and kilograms appear straight away.

The Formula

  pounds     = stone × 14 + extra pounds
  kilograms  = pounds × 0.45359237
  1 stone    = 14 lb = 6.35029318 kg

A stone is exactly 14 pounds, and the pound is exactly 0.45359237 kilograms, so both steps are exact.

Step-by-Step Example

11 stone 4 pounds.

  Pounds:     11 × 14 + 4 = 154 + 4 = 158 lb
  Kilograms:  158 × 0.45359237 = 71.6676 kg

So 11 st 4 lb is 158 pounds, or 71.6676 kg.

12.5 stone, entered as a decimal, is 12.5 × 14 = 175 pounds, which is 12 stone 7 pounds — not 12 stone 5 pounds — and about 79.3787 kg.

Quick Reference

The table below covers the range of most adult body weights. Each extra stone adds 14 pounds, or about 6.35 kilograms, so values in between are easy to work out.

   8 st  = 112 lb = 50.8023 kg
   9 st  = 126 lb = 57.1526 kg
  10 st  = 140 lb = 63.5029 kg
  11 st  = 154 lb = 69.8532 kg
  12 st  = 168 lb = 76.2035 kg
  13 st  = 182 lb = 82.5538 kg
  14 st  = 196 lb = 88.9041 kg
  15 st  = 210 lb = 95.2544 kg

Each pound adds about 0.4536 kg, so 10 st 6 lb is 63.5029 + 6 × 0.4536, about 66.2 kg.

Where the Stone Came From

The stone is an old English trading weight. Before standardisation, a stone of wool, meat or cheese could weigh anything from 5 to 20 pounds depending on the goods and the town. An Act of Parliament in 1835 fixed it at 14 pounds, and that value stuck. The stone was officially removed from use for trade in the UK in 1985, but it lives on in everyday speech, bathroom scales, slimming clubs and many doctors' conversations with patients.

Body Weight and Health

Health calculations such as body mass index, calorie needs and many medicine doses use kilograms. To work out a BMI from a weight in stone, convert to kilograms first. For example, 13 st 2 lb is 184 pounds, 83.46 kg; at a height of 1.75 m, the BMI is 83.46 ÷ 1.75² ≈ 27.3. Weight changes also convert directly: losing half a stone is losing 7 pounds, about 3.2 kg.

Converting the Other Way

To turn pounds into stone and pounds, divide by 14. The whole number is the stone and the remainder the pounds: 158 ÷ 14 = 11 remainder 4, so 158 lb is 11 st 4 lb. To turn kilograms into stone, divide by 6.35029318: 70 kg is 11.023 stone, or 11 st 0.3 lb. The calculator shows the decimal stone and the tidied stone-and-pounds form so you can check either way of writing it.

Stone in Sport

Stone survives in a few sports. Jockeys in British and Irish horse racing are still allotted weights in stone and pounds: a horse carrying 9 st 7 lb carries 133 pounds, about 60.3 kg, including the rider and saddle. Boxing weight classes were historically described in stone too, and older British boxing records often list a fighter as, say, 10 st 7 lb, which is the 147-pound welterweight limit, about 66.68 kg. Rugby and football programmes in Britain sometimes still give players' weights in stone, alongside or instead of kilograms.

Reading Bathroom Scales

Many bathroom scales sold in Britain and Ireland can switch between kilograms, pounds and stone. Some show stone and pounds with a fraction of a pound; others show decimal stone, which is easy to misread. A display of 11.4 st means 11 stone and 0.4 of a stone, which is 11 st 5.6 lb, not 11 st 4 lb. When tracking weight over time, stick to one unit, and use the calculator to convert when you need to report the figure in another.

Understanding Your Result

The headline is the total weight in pounds.

The kilograms line gives the metric weight.

The stone line shows the weight as decimal stone and as whole stone plus pounds.

The ounces line gives the weight in ounces, occasionally needed for small amounts.

When Should You Use This Calculator?

Use it to convert a UK body weight for medical forms, apps and gyms.

Use it to compare weights quoted in stone, pounds and kilograms.

Use it for BMI and diet calculations that need kilograms.

Use it for older British records, recipes and sporting weights in stone.

Common Mistakes

Treating stone as 10 pounds. A stone is 14 pounds, so 10 stone is 140 pounds.

Reading decimal stone as stone and pounds. 12.5 st is 12 st 7 lb, not 12 st 5 lb.

Adding stone and pounds directly. Multiply the stone by 14 before adding.

Using stone in medical calculations. Convert to kilograms first.

Rounding kilograms too early. Keep the full figure until the end, then round to one decimal place for everyday use.