SI Unit Prefixes: How Many Watts in Kilowatt?
Unit prefixes help dealing with very low and very large values of units - writing is easier and even the math is easier, at least up to the point.
When converting Watts in kilowatts and kilowatts in Watts, it is important to know that the prefix "kilo" means "one thousand of something". Similarly, there are other unit prefixes like mega, giga, tera, peta, exa, etc.
Published: March 11, 2023.
SI Unit Prefix "Kilo"
SI unit prefix "kilo" means "a thousand" - so, one kilowatt means one thousand watts:
1 kW = 1000 W
Similarly, one Watt is a one-thousandth of one kilowatt:
1 W = 0.001 kW
The following comparison 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.
SI prefixes range from yocto (y, 10-24) to yotta (Y, 1024) and significantly help when numbers/values are multiplied due to the simple rule in math (parentheses are added to make things more clear an easier to understand):
(A * 10x) * (B *10y) = (A+B) * 10(x+y)
For example:
200 * 3000 = (2 * 100) * (3 * 1000) = (2 * 102) * (3 * 103) = (2 * 3) * 10(2+3) = 6 * 105 = 600000
Long Story Short: If You have a value of, for example, 15400 Watts, that is 15.4 kW:
15400 Watts = 15400/1000 kW = 15.4 kW
And the math is very similar when other prefixes from the SI system of units are used.
