🧮 Calculators · Updated October 22, 2026 · 7 min read

Stone to kg and Pounds: Exact Factor, Table, st-lb Math

To convert stone to kg, multiply by 6.35029318; for pounds, multiply by 14. So 12 stone is 168 pounds or 76.20 kilograms. British and Irish body weights are usually written as a mix, such as 11 st 6 lb, so turn the whole reading into pounds first (11 × 14 + 6 = 160) and then into kilograms (72.57).

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Unit Converter on the Weight tab showing 160 lb = 72.57 kg, the metric value of 11 st 6 lb — 11 st 6 lb as pounds and kilograms in one view.

💡 Why the old unit still needs converting

Ask someone in Manchester or Dublin what they weigh and the answer usually comes back in st and lb, even from people who buy petrol in litres and food in grams. Bathroom scales sold there often offer the unit, slimming clubs have long tracked progress with it, and it turns up in newspapers, TV makeover shows and novels. Almost nobody else uses it. A British traveller at an American urgent-care clinic is asked for lb; a gym app, a ski-rental desk or a hospital in Spain wants kilograms; a US reader of a British memoir wonders how heavy 17 st really is. The arithmetic is simple once you know the unit is exactly 14 lb, but the mixed two-part notation trips up calculators, spreadsheets and people alike.

The exact stone to kg and pounds factors

Since the 1959 international agreement, the avoirdupois pound has been defined as exactly 0.45359237 kg, and the British stone is fixed at fourteen of those. That makes every factor exact rather than approximate:

One stone = fourteen pounds = 6.35029318 kilograms.
One kilogram = 0.157473 stone, or about 2.20462 pounds.
Everyday rounding: one stone ≈ 6.35 kilograms. Multiplying by 6.35 stays within a hundredth of a kilogram even at 20 stone, so it is safe for any adult body weight.
Rougher mental math: one stone is a little over six kilograms, and one kilogram is a little over two pounds. Good for a quick sanity check, never for official paperwork.

British usage keeps the plural unchanged (she weighs 9 stone), and the abbreviation is st. Do not confuse it with the metric tonne (t) or the US short ton when picking units in a list.

Stone to kg and pounds table, 10 to 20 stone

Whole values with exact pounds and kilograms rounded to two decimals, covering most adult weights:

10 st = 140 lb = 63.50 kg.
11 st = 154 lb = 69.85 kg.
12 st = 168 lb = 76.20 kg.
15 st = 210 lb = 95.25 kg.
16 st = 224 lb = 101.60 kg.
20 st = 280 lb = 127.01 kg.

For in-between readings, add about 0.45 kilograms for each extra pound: 13 st 4 lb is 186 pounds, which is 84.37 kilograms.

Mixed notation, sport weights and tracking progress

11 st 6 lb is not 11.6 st. The second number counts pounds out of fourteen, so reading it as a decimal is wrong by up to half a stone, roughly three kilograms.

Mixed to pounds: multiply the first number by fourteen and add the second. 11 st 6 lb = 160 pounds.
Mixed to decimal: add the second number divided by 14. 11 st 6 lb = 11.43 st.
Horse racing in Britain and Ireland still publishes the weight each horse carries this way, for example 9 st 7 lb, which is 133 pounds or 60.3 kilograms.
Boxing divisions are set in lb, so a 147-pound welterweight limit appears in British coverage as 10 st 7 lb, or 66.7 kilograms.

A worked progress log shows why picking one unit matters. A start of 15 st 2 lb (212 lb, 96.16 kg) and a later reading of 13 st 10 lb (192 lb, 87.09 kg) is a loss of 1 st 6 lb, which is 20 lb or 9.07 kg, about 9.4% of starting weight. Subtracting the parts directly (15 − 13 and 2 − 10) gives nonsense until you borrow fourteen pounds, so convert both readings to pounds or kilograms before comparing.

Using GrabCast's Unit Converter for st, lb and kg

The Weight category lists st beside kg, g, mg, lb, oz, metric ton, short and long tons and carats, using the exact 6.35029318 kg factor.

Type into Quick convert: 12 st to kg, 12 stone in lb or 80 kg to st.
Or pick Weight, set the two boxes to st and kg, and type in either field; the other updates and a formula line shows the multiplier.
The list under the result gives the same value in every weight unit, so pounds and kilograms appear together.
It runs in your browser, with no sign-up.

One limit: Quick convert takes a single number and unit, so 11 st 6 lb in one line is not understood. Enter 160 lb, or the decimal 11.43 st. Results come back as decimals, so multiply the fraction by 14 to recover the pounds part.

Quick convert box with 160 lb to kg typed in, the pound total of an 11 st 6 lb reading — Type the pound total as a phrase: 160 lb to kg.

Worked examples for forms and fitness tracking

Most official forms outside the UK want a single unit, so convert before you fill them in. A person weighing 12 st 5 lb is 12 × 14 + 5 = 173 lb, which is 173 × 0.45359237 = 78.47 kg. A target of 10 st 7 lb is 147 lb or 66.68 kg. Keep the pounds as the base unit while you calculate, then convert once at the end so rounding errors do not accumulate.

US forms usually want pounds, so give 173 lb rather than 12 st 5 lb.
EU and medical records use kilograms, normally to one decimal.
Fitness apps may store stone and pounds as a decimal; check the unit label before you log a value.
Dosage calculations use kilograms, so always convert precisely and ask a pharmacist if unsure.

For other conversions, converting gallons, ounces, tons and more covers common pitfalls, and mL to fl oz for travel and labels handles liquids.

Why the stone is still used

The stone survives in the UK and Ireland as an everyday measure of body weight, even though shops and the NHS use kilograms. Because one stone is exactly fourteen pounds, mental arithmetic is easy once you remember the factor, but mixed notation can confuse visitors who see 11 st 6 lb on a scale and expect a decimal.

Step-by-step

1Split the reading — Write down the stones and the pounds separately, for example 11 and 6 from 11 st 6 lb.

2Convert to pounds — Multiply the stones by fourteen and add the leftover pounds, giving 160 pounds.

All units list for 160 pounds: 72.57 kilograms, 11.43 stone and 2,560 ounces side by side — All units shows the same weight in stone, pounds and kilograms together.

3Convert to kilograms — Multiply by 0.45359237, or type 160 lb to kg in the Unit Converter.

Weight result: 160 lb equals 72.5747792 kg, with the formula multiply by 0.45359237 — The kilograms appear instantly, with the exact 0.45359237 factor.

4Round for the form — Use whole pounds for American paperwork and one decimal place of kilograms for European or medical records.

Precision set to 2 so 160 lb reads as 72.57 kg, ready for a medical or European form — Set Precision to 2 for 72.57 kg, or round to one decimal (72.6 kg) for the form.

Common mistakes to avoid

⚠️Reading 11 st 6 lb as 11.6, which overstates the weight by about a kilogram.

⚠️Multiplying by 6.3 or 6.4 instead of 6.35, which drifts by more than a kilogram at typical adult weights.

⚠️Subtracting two mixed readings part by part without borrowing, which produces a negative number of pounds.

⚠️Copying a kilogram figure into a field labeled pounds on a dosing or insurance form; the error is a factor of 2.2.

Pro tips

✓Memorize ten stone = 140 pounds = 63.5 kilograms as an anchor and adjust from there.

✓If your scale can switch units, set it to kg before a medical appointment abroad and skip the arithmetic entirely.

✓Keep a weight log in a single unit, ideally kilograms or pounds, and convert only when someone asks for stone.

✓Weigh at the same time of day on the same scale; day-to-day swings of a kilogram or two are normal and are not a units problem.

✓Use the converter's Link button to send the exact conversion to someone else.

✓Convert to pounds first when a weight is given as stones and pounds, then switch to kilograms once.

Frequently asked questions

How many kg is 1 stone?

Exactly 6.35029318 kilograms, usually rounded to 6.35 kilograms.

How many pounds is a stone?

Exactly fourteen pounds, fixed by the international definition of the pound.

What is 11 stone in kg?

69.85 kilograms, which is 154 pounds.

How do I convert kg to stone and pounds?

Divide kilograms by 6.35029318, keep the whole number as stones, and multiply the decimal part by fourteen for the remaining pounds. 70 kg is 11.02, just over 11 st (11 st 0.3 lb).

Can I type 11 st 6 lb into the Unit Converter?

Not in one line. Enter 160 lb, or 11.43 st, and it converts both ways.

📌 Bottom line

One stone is exactly fourteen pounds and 6.35029318 kilograms. Turn mixed readings into a single unit before doing any arithmetic, track progress in that one unit, and round only at the end to whatever the form in front of you expects.

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