SI Units Home
The International System of Units (SI units) is founded on seven base quantities. Each
of the quantities, such as length and time, are assumed to be independent of each other.
All seven units are explained on these pages, together with worked examples:
The SI or International System of Units (from the French Système international
d'unités) as we know it today was developed in 1960 in order to establish an
internationally agreed set of quantity measurement standards.
It has been adopted throughout the world for use in science and technology, and
by most countries for day-to-day use. Exceptions to the latter include the US and,
in some instances, the UK which uses a mixed system for everyday commerce.
To learn more about individual SI units click on the unit names in the table above
or choose from the pages below for related pages and guides.
Derived units
Individual SI units can be combined to form derived units, such as the watt, coulomb
and joule. You can see a list of derived units here.
Unit conversions
It’s often necessary or useful to convert one type of unit into another, such as kilometres
into miles, kilograms into pounds or kelvin into Fahrenheit etc. You can do so
automatically by tapping here.
Metric prefix units
Most people know that kilo usually means 1000, so there are 1000 metres in a
kilometre. Likewise, milli may be added to metre to form the word millimetre, i.e. one
thousandth of a metre. You can see a complete list of metric prefixes here.
SI Units Explained
Calculators
A series of calculators, explanations and examples, including speed, distance and time,
power, energy and time, density, momentum (including a recoil calculator), and
calculators for force (F = ma), the newton and many more.
Base quantity
Amount of substance
Electric current
Length
Luminous intensity
Mass
Thermodynamic temperature
Time
Unit
mole
ampere
metre
candela
kilogram
kelvin
second
Symbol
mol
A
m
cd
kg
K
s
MS Word Equation Editor Guides
Quick and easy guides to the Microsoft Equation Editor. Fast editing and aligning at
the equals sign etc. Equation and symbol templates. Helps to make your
mathematical work neat and professional, and saves a lot of time.
How to Memorize Equations
A visual method for memorizing equations which becomes second nature with a little
practise. The method explained with easy-to-follow examples.
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SI Units Home
The International System of Units (SI units) is founded on seven
base quantities. Each of the quantities, such as length and time,
are assumed to be independent of each other. All seven units
are explained on these pages, together with worked examples:
The SI or International System of Units (from the French
Système international d'unités) as we know it today was
developed in 1960 in order to establish an internationally agreed
set of quantity measurement standards.
It has been adopted throughout the world for use in science and
technology, and by most countries for day-to-day use.
Exceptions to the latter include the US and, in some instances,
the UK which uses a mixed system for everyday commerce.
Tap here for the formal definitions of each of the 7 base units.
Unit conversions
It’s often necessary or useful to convert one type of unit into
another, such as kilometres into miles, kilograms into pounds or
kelvin into Fahrenheit etc. You can do so automatically by
tapping here.
Metric prefix units
Most people know that kilo usually means 1000, so there are
1000 metres in a kilometre. Likewise, milli may be added to
metre to form the word millimetre, i.e. one thousandth of a
metre. You can see a complete list of metric prefixes here.
Derived units
Individual SI units can be combined to form derived units, such
as the watt, coulomb and joule. You can see a list of derived
units here.
Calculators
A series of calculators, explanations and examples, including
speed, distance and time, power, energy and time, density,
momentum (including a recoil calculator), and calculators for
force (F = ma), the newton and many more.
MS Word Equation Editor Guides
Quick and easy guides to the Microsoft Equation Editor. Fast
editing and aligning at the equals sign etc. Equation and symbol
templates. Helps to make your mathematical work neat and
professional, and saves a lot of time.
Base quantity
Amount of substance
Electric current
Length
Luminous intensity
Mass
Thermodynamic temperature
Time
Unit
mole
ampere
metre
candela
kilogram
kelvin
second
Symbol
mol
A
m
cd
kg
K
s
How to Memorize Equations
A visual method for memorizing equations which becomes
second nature with a little practise. The method explained with
easy-to-follow examples.