SI Unit Prefixes: How Many Watts in Kilowatt?

Unit prefixes are an excellent way of writing things shorter, but still keeping the results as accurate as possible.

However, some prefixes, no matter how simple they look, can be confusing and lead to mistakes. Here is the list of the SI prefixes commonly used not only in electronics but in every walk of life...

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In order to write down very large or very small numbers, SI prefixes are used.

For example, 1 W means 'one watt', 1 kW means 'one kilowatt', which is equal to 1000 W (thousand watts). The following chart lists prefixes used in the International System of Units (SI):

Prefix Base 10 Decimal English Word
Name Symbol Short Scale Long Scale
yotta Y 1024 1 000 000 000 000 000 000 000 000 septillion quadrillion
zetta Z 1021 1 000 000 000 000 000 000 000 sextillion trilliard
exa E 1018 1 000 000 000 000 000 000 quintillion trillion
peta P 1015 1 000 000 000 000 000 quadrillion billiard
tera T 1012 1 000 000 000 000 trillion billion
giga G 109 1 000 000 000 billion milliard
mega M 106 1 000 000 million
kilo k 103 1 000 thousand
hecto h 102 100 hundred
deca da 101 10 ten
- - 100 1 one
deci d 10-1 0.1 tenth
centi c 10-2 0.01 hundredth
milli m 10-3 0.001 thousandth
micro μ 10-6 0.000 001 millionth
nano n 10-9 0.000 000 001 billionth milliardth
pico p 10-12 0.000 000 000 001 trillionth billionth
femto f 10-15 0.000 000 000 000 001 quadrillionth billiardth
atto a 10-18 0.000 000 000 000 000 001 quintillionth trillionth
zepto z 10-21 0.000 000 000 000 000 000 001 sextillionth trilliardth
yocto y 10-24 0.000 000 000 000 000 000 000 001 septillionth quadrillionth

Note: 'Short Scale' is in use in, for example, the United States, while 'Long Scale' is in use in, for example, Europe.

Unit conversions

Unit conversions are relatively easy, just be sure not to mix when to add and when to remove zeroes.

For example, how many watts (W) is in a kilowatt (kW) - prefix is 'k', its name is 'kilo', decimal is 1000 and the English word is thousand. Thus, one kilowatt is 1000 watts.

How Man Kilowatts are in the Megawatt?

There are many ways of counting this, but perhaps the easiest way is:

1 kW = 1 000 W

1 MW = 1 000 000 W → 1 MW = 1 000 kW

Also, one has to know some math basics, and one them is:

10A * 10B = 10A+B

For example:

1015 * 10-9 = 10(15-9)=106

Thus:

1 MW = 106 W = 10(3+3) W = 103 * 103 W = 1 000 kW

Similarly, if you want to convert very small units, for example, μA (micro Amps), commonly used in small batteries like LR44 and similar, use:

10A * 10B = 10A+B

formula.


Using SI Unit prefixes can greatly help when calculating very large or very small values of most common electric and non-electric units.

At first, they may seem confusing, but after some practice, they are very easy to understand and to use.