Metric Conversion Charts: Units, Prefixes, and Guides
Author: Ian C. Langtree - Writer/Editor for Disabled World (DW)
Published: 20 Dec 2017 - Updated: 29 Aug 2026
Publication Type: Charts, Graphs, Tables
Table of Contents:
Synopsis - Definition - Overview - FAQs - Insights, Updates - Related Content
Synopsis
This information presents a comprehensive overview of metric conversions and measurement charts, detailing the structure and logic of the metric system, including its base units, prefixes, and practical applications for area, length, mass, and volume. The resource is particularly authoritative and useful as it breaks down complex metric concepts into accessible tables and explanations, making it easier to understand and apply metric measurements in daily life, healthcare, and accessible environments. The article also discusses global adoption of the metric system, contrasts it with the U.S. customary system, and highlights real-world consequences of conversion errors, such as the NASA Mars Climate Orbiter incident. Authored by an experienced editor and disability advocate, the content is both reliable and relevant, offering essential reference material for anyone needing clear, accurate measurement conversions.
At a Glance
- 1 - The metric system is decimalized, with units related by powers of ten. This makes conversions as simple as shifting a decimal point.
- 2 - Liberia and Burma are the only nations besides the United States that have not officially adopted the metric system. Most other countries switched within the past 30 to 40 years.
- 3 - One liter of water equals one cubic decimeter and weighs one kilogram, while one milliliter equals one cubic centimeter and weighs one gram. These clean relationships link volume, mass, and length together.
- 4 - The 125 million dollar NASA Mars Climate Orbiter was lost because engineers mixed Imperial pound-seconds with metric newton-seconds. Lockheed Martin supplied data in English units while JPL calculated in metric ones.
Topic Definition
- Metric System
The metric system is a decimalized way of measuring things in which every unit relates to the next by a factor of ten, so quantities scale up or down through tidy steps of 10, 100, or 1,000 rather than the awkward fractions found in older systems. It is built around a handful of base units - the meter for length, the gram for mass, and the liter for volume - which are then stretched or shrunk using standard prefixes such as kilo for a thousand, centi for a hundredth, and milli for a thousandth. What makes it so practical is that these prefixes work the same way no matter what you are measuring, which is why most of the world relies on it for personal, commercial, and scientific work alike. Because everything hinges on powers of ten, converting between units usually means nothing more than moving a decimal point, a simplicity that has made the metric system the common language of measurement across borders and disciplines.
Overview
What is the Metric Measurement System?
The metric system is a decimalised system of measurement. Multiples and submultiples are related to the fundamental unit by factors of powers of ten eg. 10, 100, 1000. The names of multiples and submultiples are formed with prefixes. They include deca (ten), hecto (hundred), kilo (thousand), mega (million), and giga (billion), deci (tenth), centi (hundredth), milli (thousandth), micro (millionth), and Nano (billionth). Metric units are commonly used around the world for personal, commercial and scientific purposes.
What is an Are?
An Are is a unit of area equal to 100 square metres (10 m by 10 m), used for measuring land area. It is mainly used in French, Portuguese, Polish, Dutch and German-speaking countries to measure real estate, elsewhere, the square metre is usually used.
What is a Centiare?
A centiare is a unit of area, equal to 1 square meter. 1 centiare = 0.01 ares = 1 square metre = 1 m2 = 1 m by 1 m.
The are is sometimes used in combination with the centiare, e.g. "10 ares 12 centiares" = 1012 m2.
| 1000 litres = 1 cubic meter = 1 tonne of water |
| 1 litre = 1 cubic decimeter = 1 kilogram of water |
| 1 millilitre = 1 cubic centimeter = 1 gram of water |
| 1 microlitre = 1 cubic millimeter = 1 milligram of water |
| 100 square millimeter (mm2) | 1 square centimeter (cm2) |
| 100 square centimeter | 1 square decimeter (dm2) |
| 100 square decimeters | 1 square meter (m2) |
| 100 square meters | 1 square dekameter (dam2) = 1 are |
| 100 square dekameters | 1 square hectometer (hm2) = 1 hectare (ha) |
| 100 square hectometers | 1 square kilometer (km2) |
| 10 milligrams (mg) | 1 centigram (cg) |
| 10 centigrams | 1 decigram (dg) = 100 milligrams |
| 10 decigrams | 1 gram (g) = 1000 milligrams |
| 10 grams | 1 dekagram (dag) |
| 10 dekagrams | 1 hectogram (hg) = 100 grams |
| 10 hectograms | 1 kilogram (kg) = 1000 grams |
| 1000 kilograms | 1 megagram (Mg) or 1 metric ton(t) |
| 10 millimeters (mm) | 1 centimeter (cm) |
| 10 centimeters | 1 decimeter (dm) = 100 millimeters |
| 10 decimeters | 1 meter (m) = 1000 millimeters |
| 10 meters | 1 dekameter (dam) |
| 10 dekameters | 1 hectometer (hm) = 100 meters |
| 10 hectometers | 1 kilometer (km) = 1000 meters |
| 10 milliliters (mL) | 1 centiliter (cL) |
| 10 centiliters | 1 deciliter (dL) = 100 milliliters |
| 10 deciliters | 1 liter1 = 1000 milliliters |
| 10 liters | 1 dekaliter (daL) |
| 10 dekaliters | 1 hectoliter (hL) = 100 liters |
| 10 hectoliters | 1 kiloliter (kL) = 1000 liters |
| 1000 cubic millimeters (mm3) | 1 cubic centimeter (cm3) |
| 1000 cubic centimeters | 1 cubic decimeter (dm3) 1 000 000 cubic millimeters |
| 1000 cubic decimeters | 1 cubic meter (m3) 1 000 000 cubic centimeters 1 000 000 000 cubic millimeters |
Metric (SI) Prefixes
In some fields it is far more convenient to provide for multiples larger than 1,000 and for subdivisions smaller than 1,000th. In the metric system of measurement, designations of multiples and subdivision of any unit may be arrived at by combining with the name of the unit the prefixes deka, hecto, and kilo meaning, respectively, 10, 100, and 1000, and deci, centi, and milli, meaning, respectively, one-tenth, one-hundredth, and one-thousandth. The following decimal multiples, and sub multiples, of SI unit prefixes are generally recognized and in use today. They are written using the SI prefixes listed in the charts below:
| Whole Units | Decimal Units | |||||
|---|---|---|---|---|---|---|
| Thousands | Hundreds | Tens | SI unit* | Tenths | Hundredths | Thousandths |
| 1000 | 100 | 10 | 1 | 0.1 | 0.01 | 0.001 |
| kilo- | hecto- | deka- | meter gram liter |
deci- | centi- | milli |
* SI base or derived units with special names may be used
| Larger Quantities or Whole Units Prefixes | |||||
|---|---|---|---|---|---|
| Prefix Name | Pronunciation | Symbol | Value | Multiplying Factor | |
| yotta | Yä-tuh | Y | 1024 | Septillion | 1 000 000 000 000 000 000 000 000 |
| zetta | ZETT-uh | Z | 1021 | Sextillion | 1 000 000 000 000 000 000 000 |
| exa | EX-uh | E | 1018 | Quintillion | 1 000 000 000 000 000 000 |
| peta | PET-uh | P | 1015 | Quadrillion | 1 000 000 000 000 000 |
| tera | TAIR-uh | T | 1012 | Trillion | 1 000 000 000 000 |
| giga | JIG-uh | G | 109 | Billion | 1 000 000 000 |
| mega | MEG-uh | M | 106 | Million | 1 000 000 |
| kilo | KILL-oh | k | 103 | Thousand | 1 000 |
| hecto | HECK-toe | h | 102 | Hundred | 100 |
| deka | DECK-uh | da | 101 | Ten | 10 |
| 100 | One | 1 | |||
| Smaller Quantities or Sub Unit Prefixes | |||||
| deci | DESS-ih | d | 10-1 | Tenth | 0.1 |
| centi | SENT-ih | c | 10-2 | Hundredth | 0.01 |
| milli | MILL-ih | m | 10-3 | Thousandth | 0.001 |
| micro | MI-crow | μ | 10-6 | Millionth | 0.000 001 |
| nano | NAN-oh | n | 10-9 | Billionth | 0.000 000 001 |
| pico | PEEK-oh | p | 10-12 | Trillionth | 0.000 000 000 001 |
| femto | FEM-toe | f | 10-15 | Quadrillionth | 0.000 000 000 000 001 |
| atto | AT-toe | a | 10-18 | Quintillionth | 0.000 000 000 000 000 001 |
| zepto | ZEP-toe | z | 10-21 | Sextillionth | 0.000 000 000 000 000 000 001 |
| yocto | YOCK-toe | y | 10-24 | Septillionth | 0.000 000 000 000 000 000 000 001 |
Who Uses the Metric System?
Most countries have either used the metric system for many years, or have adopted the metric system within the past 30 or 40 years. The only countries besides the U.S. that have not officially adopted the metric system are Liberia (Africa) and Burma (Southeast Asia). However the use of the metric system in the U.S. is slowly due to increasing wider acceptance of global standards and global trade which usually use metric measurements.
Why Doesn't America Use the Metric System?
America has always wanted to be different since it gained independence from England - The US declared independence on July 4th 1776 but did not gain independence until September 3, 1783 after the American Revolutionary War or the American War of Independence - One of the first things they changed was producing left hand drive cars and driving on the right side of the road, (as opposed to the R/H drive, L/H side of the road British system), as they were anxious to cast off all remaining links with their British colonial past. This mentality seems to continue today with the reluctance of the US to adopt the far more practical metric system into everyday use.
In fact the reluctance of the US to convert to the metric system resulted in the loss of the $125 million NASA Mars Climate Orbiter because spacecraft engineers failed to convert from Imperial to metric measurements when exchanging data before the craft was launched. A navigation team at the Jet Propulsion Laboratory (JPL) used the metric system in its calculations, while Lockheed Martin Astronautics in Denver, which built the orbiter, provided acceleration data in the English Imperial system of inches, feet and pounds. JPL engineers mistook acceleration readings in English units of pound-seconds for a metric measure of force called newton-seconds.
It is ironic that the US can cooperate in space with the Russians, Japanese, and French yet have trouble communicating across different areas of the United States...
Frequently Asked Questions
What is the difference between the metric system and the SI system
The SI system, or International System of Units, is the modern and formally standardized version of the metric system used in science and international trade. The term metric system is broader and older, covering earlier decimal systems that the SI later refined and unified.
How do you convert kilometers to miles
To convert kilometers to miles you multiply the number of kilometers by roughly 0.621. For a quick estimate you can also divide the kilometer figure by 1.609.
Why is the metric system easier to use than the imperial system
The metric system is based on powers of ten, so converting between units only requires moving a decimal point rather than memorizing irregular factors. The imperial system uses varied numbers like 12 inches to a foot and 16 ounces to a pound, which makes calculations more complex.
What are the seven base units of the SI system
The seven base units are the meter for length, kilogram for mass, second for time, ampere for electric current, kelvin for temperature, mole for amount of substance, and candela for luminous intensity. All other SI units are derived from these seven.
Is a metric ton the same as a US ton
No, a metric ton equals 1,000 kilograms or about 2,205 pounds, while a US short ton equals 2,000 pounds. The two measures are close but not identical, so the distinction matters in trade and engineering.
When was the metric system first created
The metric system was first introduced in France in the 1790s during the French Revolution as a unified standard of measurement. It has since been revised and expanded into the modern SI system adopted worldwide.
What does the prefix kilo actually mean
The prefix kilo means one thousand, so a kilometer is 1,000 meters and a kilogram is 1,000 grams. It is one of the most widely used metric prefixes in everyday life.
Does the United States use the metric system at all
Yes, the United States uses the metric system in science, medicine, the military, and many manufacturing sectors even though everyday life still relies on customary units. Its use has grown steadily because of global trade and international standards.
Insights, Analysis, and Developments
Editorial Note: As the world becomes increasingly interconnected, a solid grasp of the metric system is more valuable than ever. This article not only clarifies the intricacies of metric measurements but also underscores the practical importance of standardized units, especially for those navigating health, accessibility, or international communication. Whether for personal use, professional tasks, or supporting accessible environments, these charts and explanations are a vital tool for bridging gaps in understanding and ensuring accuracy in everyday life.
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.