Stone to Pounds and Kilograms Weight Converter and Chart

Author: Ian C. Langtree - Writer/Editor for Disabled World (DW)
Published: 4 Jan 2014 - Updated: 27 Sep 2026
Publication Type: Conversion, Calculation

Table of Contents:
Synopsis - Definition - Overview - FAQs - Insights, Updates - Related Content

Synopsis

This information gives readers a calculator and a printable reference chart for converting body weight between stones, pounds, and kilograms. It covers weights from 7 stone 1 pound (45 kilograms) up to 22 stone (140 kilograms). One stone equals exactly 14 pounds, or 6.35029318 kilograms. These figures are not estimates: they come from the 1959 international definition of the avoirdupois pound as exactly 0.45359237 kilograms, a standard kept by NIST, the UK National Physical Laboratory, and the International Bureau of Weights and Measures. The tool is especially useful for people in the United Kingdom and Ireland, where body weight is still commonly given in stone. It also helps anyone who has to compare figures across the imperial and metric systems. The healthcare angle is the part that matters most. Many medications are dosed per kilogram of body weight, so accurate conversion helps patients, caregivers, seniors, and people with disabilities keep their weight records consistent across providers, scales, and countries.

At a Glance

• 1 - One avoirdupois ounce equals 437.5 grains, and 16 of those ounces make up one avoirdupois pound.
• 2 - In U.S. law the metric system is preferred but compliance is voluntary, so many people and industries mix both systems.
• 3 - Many modern bathroom scales include a display setting that switches readings between kilograms, pounds, and stone/pounds.
• 4 - Before England fixed it at 14 pounds, a medieval stone could range from about 5 to more than 40 pounds depending on the goods being weighed.

Topic Definition

Stone (Unit of Weight)

A stone is a British imperial unit of weight equal to exactly 14 pounds, or 6.35029318 kilograms. People in the United Kingdom and Ireland still use it mainly to describe body weight. A weight such as 11 stone 4 means 11 stone plus 4 extra pounds, which comes to 158 pounds. The stone started out as a loose trading measure in medieval Europe, when actual stones were placed on balance scales, and its size changed from place to place and from one commodity to another. England eventually standardized it at 14 pounds. Since the international pound was fixed in 1959 as exactly 0.45359237 kilograms, the stone's metric value has also been exact. That lets it be converted precisely to pounds and kilograms for health, travel, and everyday use.

Overview

What is a Stone in Weight Measurement?

The stone (st) is a unit of measure equal to 14 pounds (lb) or 6.3503 kilograms (kg). The plural of stone is also stone. The stone measurement remains widely used in Britain, Australia, and Ireland for measuring human body weight. In the U.K., Australia, New Zealand, and Ireland, people may be said to weigh, e.g., "11 stone 4" (11 stones and 4 pounds), rather than "72 kilograms", or "158 pounds", as in the United States (US). Many scales today provide a "change weight display" setting that you can select to display either kilograms, pounds, or stone/pounds.

The stone began as a practical trading weight in medieval Europe, when actual stones were used on balance scales to weigh goods such as wool, meat, and produce. Because a "stone" varied from town to town and commodity to commodity - ranging anywhere from around 5 to over 40 pounds depending on what was being weighed - England gradually standardized it, ultimately fixing the stone at 14 pounds for general use. That 14 pound stone survived into modern British and Irish life as the customary way to describe human body weight, which is why it remains familiar today even though the United Kingdom has otherwise largely adopted the metric system.

Quick Stone Conversions:

• 1 stone = 14 pounds
• 1 stone = 6.35029318 kilograms
• To convert kilograms to stones, divide by 6.35029318
• To convert stones to kilograms, multiply by 6.35029318

Standards and Accuracy

The conversion factors used on this page are not approximations - they are fixed by international agreement. Since 1959, the international avoirdupois pound has been defined as exactly 0.45359237 kilograms, a standard maintained by national metrology institutes including the U.S. National Institute of Standards and Technology (NIST) and the United Kingdom's National Physical Laboratory (NPL), under the framework of the International Bureau of Weights and Measures (BIPM). Because one stone equals exactly 14 pounds, it follows that one stone equals exactly 6.35029318 kilograms (14 x 0.45359237). Our calculator applies this exact factor, and the printable table above is rounded to one decimal place for kilograms to keep it easy to read. For everyday health, fitness, and travel use these figures are precise; for clinical or legal purposes, always confirm against the full unrounded value. Conversions on this page are verified against NIST and NPL standard factors, last reviewed June 13, 2026.

How the Conversion Works - A Worked Example To see the method in action, take a weight given in British style as "11 stone 4." First convert the stones to pounds and add the loose pounds: (11 x 14) + 4 = 158 pounds. Then convert pounds to kilograms by dividing by 2.20462: 158 ÷ 2.20462 = 71.7 kilograms. Working the other way, to turn kilograms into stones you divide by 6.35029318, so 71.7 ÷ 6.35029318 = 11.29 stone, where the 0.29 represents the leftover 4 pounds. Showing the steps this way makes it clear that nothing is estimated - each result comes straight from the fixed relationships between the units.

Chart to Convert Stones to Kilograms and Pounds

Below the chart is an easy-to-read weight conversion calculator for Stone, Pounds, and Kilograms, and a stone conversion graph.

Calculator to Convert Stones to Pounds and/or Kilograms

Enter the value you know in the appropriate box, and the other figures will be instantly calculated for you.

Stones to Pounds Conversion Graph

Avoirdupois

An avoirdupois ounce is a unit of weight equal to 28.35 grams and is defined as 1/16 of an avoirdupois pound (there are 16 ounces in a pound). It is the standard ounce used for everyday weighing and is distinct from the troy ounce, which is used for precious metals and weighs more (31.10) grams.

• 1 avoirdupois ounce = 28.35 grams
• 1 avoirdupois ounce = 437.5 grains
• 16 avoirdupois ounces = 1 avoirdupois pound

Why Accurate Weight Conversion Matters in Healthcare

For people managing their health, getting a weight conversion right is more than a convenience. Many medications, particularly in pediatric, anesthetic, and chemotherapy care, are dosed per kilogram of body weight, so a unit mix-up between pounds and kilograms can lead to a serious dosing error. Patients who think in stones and pounds but are treated by clinicians working in kilograms - common across the UK and Ireland - benefit from converting their weight accurately before appointments. For disabled and older adults who track weight as part of ongoing care, a reliable conversion ensures records stay consistent across different providers, scales, and countries.

Countries That Use Imperial and Metric Systems

In Australia, New Zealand, and increasingly so in Canada, the metric system (kilograms) has replaced the measurement of stone and pounds since the 1960's-70's.

The stone unit of measurement is still used in Great Britain, Ireland, and by some people in Australia for measuring human body weight, as it will probably take a generation or more for populations to fully convert to the metric system (i.e., kilograms instead of stones or pounds). People in those countries who still use the stone unit of measurement are said to weigh, for example, 11 stone 4 (11 stone and 4 pounds), which is approximately 72 kilograms or 158 pounds.

The United States still uses the older Imperial system, e.g., pounds as body weight measurement; however, U.S. law has indicated the metric system to be preferred, but not the only one allowed. Compliance is totally voluntary - some people and industries convert fully, some not at all, and most are a mix - resulting in ongoing confusion both domestically and internationally from not using the metric system consistently.

Frequently Asked Questions

How many pounds are in a stone? One stone equals exactly 14 pounds.

How many kilograms are in a stone? One stone equals exactly 6.35029318 kilograms, which is often rounded to 6.35 kg.

How do I convert kilograms to stones? Divide the number of kilograms by 6.35029318.

How do I convert stones to kilograms? Multiply the number of stones by 6.35029318.

Which countries still use the stone? The stone is still commonly used for body weight in the United Kingdom and Ireland, and by some people in Australia and New Zealand, although those countries have largely moved to kilograms.

Is the everyday ounce the same as the troy ounce? No. The everyday avoirdupois ounce weighs 28.35 grams, while the troy ounce used for precious metals is heavier at 31.10 grams.

References and Sources

• National Institute of Standards and Technology (NIST) - NIST Handbook 44 and the Office of Weights and Measures, definitions of the avoirdupois pound and ounce.
• National Physical Laboratory (NPL) - the United Kingdom's national metrology institute, unit of mass (the kilogram).
• International Bureau of Weights and Measures (BIPM) - The International System of Units (SI).
• UK Government (GOV.UK) - guidance on metric and imperial units of measurement permitted for use in the United Kingdom.

Frequently Asked Questions

How many stone is 100 kilograms?

100 kilograms is about 15.75 stone, which works out to roughly 15 stone 10 pounds.

How do I convert pounds to stones and pounds?

Divide the total pounds by 14. The whole number is the stone, and the remainder is the leftover pounds, so 200 pounds becomes 14 stone 4 pounds.

How many grams are in one stone?

One stone equals about 6,350.29 grams, since it is exactly 14 pounds and each pound is 453.59237 grams.

What is a hundredweight and how does it relate to the stone?

In the British system a long hundredweight is 112 pounds, which equals exactly 8 stone. In the United States a short hundredweight is 100 pounds.

Is a metric tonne the same as a ton?

No. A metric tonne is 1,000 kilograms, a British long ton is 2,240 pounds or 160 stone, and a U.S. short ton is 2,000 pounds.

Can I calculate BMI if I only know my weight in stone?

Yes. Convert your weight to kilograms first by multiplying the stone value by 6.35029318, then divide that figure by your height in meters squared.

Do UK hospitals record weight in stone or kilograms?

UK hospitals and clinics generally record weight in kilograms, even though many patients still know their own weight in stone and pounds.

How can I get the most consistent readings from a home scale?

Place the scale on a hard, level floor, weigh yourself at the same time of day in similar clothing, and keep the scale set to one unit to avoid confusion.

Insights, Analysis, and Developments

Editorial Note: The stone has hung on as a way of describing body weight long after Britain and Ireland moved most other measurements to metric. That leaves millions of people who think of themselves as 11 stone 4 while their clinic, pharmacy, or fitness app records them as 71.7 kilograms. A converter like this bridges that gap in seconds. It also shows the working, so readers can see that each result follows directly from fixed relationships between the units and is not a guess. For travelers, families caring for relatives abroad, and anyone moving between providers who use different systems, a dependable conversion chart is a small tool that prevents real mistakes. In medical settings, where a single unit mix-up can change a dose, that reliability matters most.

Author Credentials: Ian is the founder and Editor-in-Chief of Disabled World, a leading resource for news and information on disability issues. With a global perspective shaped by years of travel and lived experience, Ian is a committed proponent of the Social Model of Disability, a transformative framework developed by disabled activists in the 1970s that emphasizes dismantling societal barriers rather than focusing solely on individual impairments. His work reflects a deep commitment to disability rights, accessibility, and social inclusion. To learn more about Ian's background, expertise, and accomplishments, visit his full biography.