Definitions of the SI units: The twenty SI prefixes (2023)

Definitions of the SI units: The twenty SI prefixes (1) SI prefixes

See also prefixes for binary multiples adopted by the IEC.

(Video) What are SI Prefixes? (Measurements)

The 20 SI prefixes used to form decimal multiples and submultiples of SI units are given in Table 5.

(Video) Units, Standards and the S.I. System

Table 5. SI prefixes
Factor Name Symbol
1024 yotta Y
1021 zetta Z
1018 exa E
1015 peta P
1012 tera T
109 giga G
106 mega M
103 kilo k
102 hecto h
101 deka da
Factor Name Symbol
10-1 deci d
10-2 centi c
10-3 milli m
10-6 micro µ
10-9 nano n
10-12 pico p
10-15 femto f
10-18 atto a
10-21 zepto z
10-24 yocto y

It is important to note that the kilogram is the only SI unit with a prefix as part of its name and symbol. Because multiple prefixes may not be used, in the case of the kilogram the prefix names of Table5 are used with the unit name "gram" and the prefix symbols are used with the unit symbol "g." With this exception, any SI prefix may be used with any SI unit, including the degree Celsius and its symbol °C.

(Video) S.I. base units and derived units

Example 1: 10-6 kg = 1 mg (one milligram), but not 10-6 kg = 1 µkg (one microkilogram)
Example 2: Consider the earlier example of the height of the Washington Monument. We may write hW = 169 000 mm = 16 900 cm = 169 m = 0.169 km using the millimeter (SI prefix milli, symbol m), centimeter (SI prefix centi, symbol c), or kilometer (SI prefix kilo, symbol k).

Because the SI prefixes strictly represent powers of 10, they should not be used to represent powers of 2. Thus, one kilobit, or 1 kbit, is 1000 bit and not 210 bit = 1024 bit. To alleviate this ambiguity, prefixes for binary multiples have been adopted by the International Electrotechnical Commission (IEC) for use in information technology.

(Video) GCE (A-level) Physics G1 SI prefixes

Continue to
Units outside the SI

(Video) SI System


What are the SI prefixes and their meanings? ›

In the SI, 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.

What is SI prefixes in chemistry? ›

The International System of Units (SI) is system of units of measurements that is widely used all over the world. This modern form of the Metric system is based around the number 10 for convenience. A set unit of prefixes have been established and are known as the SI prefixes or the metric prefixes (or units).

How many SI prefixes are there? ›

The 20 SI prefixes used to form decimal multiples and submultiples of SI units are given in Table 5. It is important to note that the kilogram is the only SI unit with a prefix as part of its name and symbol.

What does SI unit mean? ›

International System of Units (SI), French Système International d'Unités, international decimal system of weights and measures derived from and extending the metric system of units. Adopted by the 11th General Conference on Weights and Measures (CGPM) in 1960, it is abbreviated SI in all languages.

What are the 20 most common prefixes? ›

  • anti- against. antifreeze.
  • de- opposite. defrost.
  • dis-* not, opposite of. disagree.
  • en-, em- cause to. encode, embrace.
  • fore- before. forecast.
  • in-, im- in. infield.
  • in-, im-, il-, ir-* not. injustice, impossible.
  • inter- between. interact.

What are prefix with 20 examples? ›

English Prefixes List, Meanings and Example Words Prefix Meaning Example Anti- Against Antifreeze, antithesis De- Opposite Decode, decompose Dis- Not, opposite of Disconnect, disembark Em- Cause to Embrace, emphasis En- Cause to Encode, encounter Fore- Before Forecast, foresight In- İn Infield, infiltrate Im- İn ...

Why is SI stand for? ›

What does "S.I." stand for? S.I. is an abbreviation of Système Internationale or International System: our metric system of measurements. It is an internationally standardised system, giving a common language between nations and between the different branches of science and technology.

What is the 12 prefix? ›

4 more rows

How do you write SI units? ›

Laws for writing SI units:
  1. The name of the unit should be written in small letters even if it is after the name of the scientist.
  2. Symbols are generally written in small letters, for example, metre (m).
  3. But the symbol of units named after scientists is written in capital letters, for example, newton (N).

How many SI units are there name them? ›

The seven Base SI Units are the Second for Time, the Metre for Length, the Ampere for Electric Current, the Candela for Luminous Intensity, the Mole for Amount of Substance, the Kilogram for Mass, and the Kelvin for Thermodynamic Temperature.

What is the SI definition of second? ›

The second, symbol s, is the SI unit of time. It is defined by taking the fixed numerical value of the cesium frequency ΔνCs, the unperturbed ground-state hyperfine transition frequency of the cesium 133 atom, to be 9 192 631 770 when expressed in the unit Hz, which is equal to s-1.

What are the SI unit symbols? ›

SI base unit
Base quantityNameSymbol
electric currentampereA
4 more rows

What are all the prefix words? ›

The most common prefixes are a-, be-, de-, dis-, ex-, in-, mis-, non-, over-, pre-, re-, uni- and with-.

What are the main prefixes? ›

The most common prefixes used to form new verbs in academic English are: re-, dis-, over-, un-, mis-, out-. The most common suffixes are: -ise, -en, -ate, -(i)fy. By far the most common affix in academic English is -ise.

What are the 10 examples of prefix? ›

Sharing is caring!
  • Anti- Against. Antisocial.
  • De- Opposite. Demotivated.
  • Un- Not. Unhappy.
  • Dis- Not, opposite of. Disagree.
  • Im- Not. Impolite.
  • Mid- Middle. Midday.
  • Mis- Wrongly. Misunderstand.
  • Over- Over. Overenthusiastic.
Aug 19, 2015

What are prefix words and examples? ›

A prefix is a letter or a group of letters that we add to the beginning of a word. Prefixes change the meanings of words. For example, the prefix un- (or u-n) can mean "not," "remove," or "opposite." Adding un- to the word "happy" gives you the word "unhappy," which means not happy.

What is a name prefix examples? ›

Name prefixes are typically Dr., Mr., Mrs., Ms., and a name suffix may be Jr., Sr., to name a few.

What are 5 words with the prefix in? ›

Prefixes and the Prefix "In"
  • inject: throw 'in'
  • influx: flow 'in'
  • inscribe: write 'on'
  • invoke: call 'on'
  • insane: 'not' sane.
  • independent: 'not' hanging from something.
  • invalid: 'not' valid.

What is the trick to learn prefixes? ›

The mnemonic for the six most commonly used prefixes from kilo to milli is King Henry Didn't Drink Chocolate Milk. You may also include a B for the base unit in the middle of the chart -- King Henry Died By Drinking Chocolate Milk.

What is the order of prefixes? ›

Orders of Magnitude Prefixes for SI Units
14 more rows

Who uses the SI units? ›

The SI has an official status in most countries, including the United States, Canada, and the United Kingdom, although these three countries are amongst a handful of nations that, to various degrees, also continue to use their customary systems.

What is SI based on? ›

As you can see above, the units in the revised SI are based completely on seven unchanging quantities or “universal constants,” including the speed of light, the amount of electric charge in an electron, and the Planck constant.

What are SI units for Grade 6? ›

SI units stands for systeme intornational (a french word) which means international system of units which means that the units have been agreed to be used throughout the world. examples of SI units are -litre , millimeter,kilogram etc. S.I init is an International standard unit which is accepted though out the world.

What prefix is +7? ›

+7 is the country calling code assigned to Russia by the International Telecommunication Union.

What are the 100 prefixes? ›

There are many prefixes being used, for example, dis-, mis-, anti-, non-, etc.
100+ Prefix Words List for Grades.
de-fromdecode, decrease, deflate, degenerate, depress
non-notnonsense, nonentity, nondescript
co-withco-worker, co-pilot, co-operation
dis-notdisagree, disallow, disarray, disconnect, disloyal, disrespect
35 more rows

What are the 7 prefixes? ›

Here are 7 common prefixes in English, together with their basic meaning and some examples:
  • counter- meaning: opposition, opposite direction. ...
  • extra- meaning: outside, beyond. ...
  • hemi- meaning: half. ...
  • inter- meaning: between, among. ...
  • non- meaning: absence, negation. ...
  • post- meaning: after in time or order. ...
  • re- meaning: again.

What are 100 examples of prefixes? ›

English Prefixes List, Meanings and Example Words Prefix Meaning Example Anti- Against Antifreeze, antithesis De- Opposite Decode, decompose Dis- Not, opposite of Disconnect, disembark Em- Cause to Embrace, emphasis En- Cause to Encode, encounter Fore- Before Forecast, foresight In- İn Infield, infiltrate Im- İn ...

What are the 6 prefixes? ›

prefixnumber indicated
6 more rows

What are 100 metric prefixes? ›

Metric Prefixes
PrefixUnit Abbrev.Meaning
8 more rows
Aug 24, 2020

How do you teach prefixes in a fun way? ›

Write some base words on popsicle sticks and add prefixes and suffixes to clothespins. Students create variations of words by adding prefix and suffix clips. Then they can write the words they create. If you do this activity in partners, students can talk about what the words mean as the prefixes and suffixes change.

What prefixes should be taught first? ›

The Two Most Common Prefixes

The most common prefixes are un and re. These two prefixes are the most useful for beginning spellers to learn because they appear frequently and their meanings are easy to understand and remember.

What are the 35 common prefixes in English? ›

35 Common Prefixes in English.
Common Prefixes.
anti-against, opposite ofanticlimax. antiaircraft, antiseptic, antibody
auto-self, sameautopilot, autobiography, automobile, autofocus
circum-around, aboutcircumvent, circumnavigate, circumscribe
co-with, togetherco-pilot, co-worker, co-exist, co-author
31 more rows
May 4, 2019

What are prefixes answer? ›

A prefix is a word part added to the beginning of a word that changes the word's meaning. A suffix is a word part added to the end of a word that changes the word's meaning. Learning the meanings of prefixes and suffixes will help expand your vocabulary, which will help improve your writing.

What prefix means 2? ›

The English prefixes bi-, derived from Latin, and its Greek counterpart di- both mean “two.” These “two” prefixes are used commonly, especially bi-. Let's begin with the frequently used English prefix bi-, which means “two.” A bicycle has “two” wheels.

What is a prefix give 5 examples? ›

The most common prefixes
down-reduce or lowerdowngrade, downhearted
extra-beyondextraordinary, extraterrestrial
hyper-extremehyperactive, hypertension
il-, im-, in-, ir-notillegal, impossible, insecure, irregular
24 more rows


1. SI System
(Brady Kurtz)
2. SI Prefixes
(Chris Morong)
3. 0 2 Scientific Notation and SI Prefixes
(Diana LaBarbera)
4. SI Units
(Chris Morong)
5. 130 SI Prefixes
6. Metric Unit Prefixes
(PaNDa Chemistry)


Top Articles
Latest Posts
Article information

Author: Dan Stracke

Last Updated: 07/10/2023

Views: 5311

Rating: 4.2 / 5 (43 voted)

Reviews: 90% of readers found this page helpful

Author information

Name: Dan Stracke

Birthday: 1992-08-25

Address: 2253 Brown Springs, East Alla, OH 38634-0309

Phone: +398735162064

Job: Investor Government Associate

Hobby: Shopping, LARPing, Scrapbooking, Surfing, Slacklining, Dance, Glassblowing

Introduction: My name is Dan Stracke, I am a homely, gleaming, glamorous, inquisitive, homely, gorgeous, light person who loves writing and wants to share my knowledge and understanding with you.