Weight Converter: Stones, Pounds and Kilograms

Author: Ian C. Langtree - Writer/Editor for Disabled World (DW)
Published: 4 Jan 2014 - Updated: 13 Jun 2026
Publication Type: Conversion, Calculation

Contents: Synopsis - Definition - Introduction - Main - Insights, Updates - Related Publications

Synopsis: This page provides a user-friendly weight calculator and printable chart for converting measurements from stones to pounds, kilograms, and ounces. It is particularly useful for individuals in regions where the stone is still a common unit of measure, like the United Kingdom (UK) and Ireland, and sometimes in parts of the Commonwealth, like Australia and New Zealand, helping to quickly and accurately convert weights for health, fitness, or daily life purposes. The tool enhances understanding by offering conversions in both directions, thus bridging the gap between imperial and metric systems, which can be especially helpful in medical contexts, international communication, or when dealing with diverse measurement standards.

At a Glance

• 1 - One stone equals exactly 14 pounds or about 6.35 kilograms, and in everyday British or Irish use a person might say they weigh "11 stone 4," meaning 11 stone and 4 pounds, rather than giving a single pound or kilogram figure.
• 2 - The everyday avoirdupois ounce weighs 28.35 grams, but it is not the same as the troy ounce used for precious metals, which is heavier at 31.10 grams.
• 3 - Australia, New Zealand, and increasingly Canada largely switched to kilograms back in the 1960s and 70s, while the United States keeps the Imperial system and treats metric use as preferred but voluntary.

Topic Definition: Weight Converter

A weight converter is a simple tool, usually a calculator paired with a reference chart, that translates a body weight or object weight from one unit of measure into another, most commonly between stones, pounds, and kilograms. It exists because different parts of the world count weight in different ways. People in Britain and Ireland still talk in stones, the United States sticks with pounds, and most other countries have moved to kilograms, so the same person can be described by three very different sounding numbers. By letting you enter a figure in whatever unit you already know and instantly showing the equivalents, a converter bridges the gap between the imperial and metric systems, which is handy for everything from tracking your health and reading a doctor's notes to traveling or comparing measurements with someone overseas. At its heart it relies on fixed relationships, such as 14 pounds to a stone and roughly 6.35 kilograms to a stone, to keep the results consistent and accurate.

Introduction

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

Main Content

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.

Insights, Analysis, and Developments

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.