# SI Prefixes: How Many Watts in a Kilowatt and Kilowatts in a Megawatt and Vice Versa

SI prefixes are very important in electrical engineering but also in everyday life. Their use is relatively easy, but it can also cause many problems when done incorrectly.

Watts to kilowatts, kilowatts to megawatts, and other conversions are very important when electric energy and power of electric motors, pumps, winches, inverters, batteries, and other devices are being calculated, planned, transferred, or being used. SI prefixes help significantly, especially when dealing with very large or very small values.

**Updated: January 15, 2024.**

## Standard SI Prefixes

SI prefixes are used in order to write down a very large or very small numbers - after all, it is much easier to write, for example, 25 kW than 25000 watts. But, it is also much easier to write 25 MW than 25000 kW or 25000000 watts.

The following chart lists the International System of Units (SI) official prefixes:

Prefix |
Base 10 |
Decimal |
English Word |
||

Name |
Symbol |
Short Scale |
Long Scale |
||

quetta | Q | 10^{30} |
1 000 000 000 000 000 000 000 000 000 000 | nonillion | quintillion |

ronna | R | 10^{27} |
1 000 000 000 000 000 000 000 000 000 | octillion | quadrilliard |

yotta | Y | 10^{24} |
1 000 000 000 000 000 000 000 000 | septillion | quadrillion |

zetta | Z | 10^{21} |
1 000 000 000 000 000 000 000 | sextillion | trilliard |

exa | E | 10^{18} |
1 000 000 000 000 000 000 | quintillion | trillion |

peta | P | 10^{15} |
1 000 000 000 000 000 | quadrillion | billiard |

tera | T | 10^{12} |
1 000 000 000 000 | trillion | billion |

giga | G | 10^{9} |
1 000 000 000 | billion | milliard |

mega | M | 10^{6} |
1 000 000 | million | |

kilo | k | 10^{3} |
1 000 | thousand | |

hecto | h | 10^{2} |
100 | hundred | |

deca | da | 10^{1} |
10 | ten | |

- | - | 10^{0} |
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 |

ronto | r | 10^{-27} |
0.000 000 000 000 000 000 000 000 001 | octillionth | quadrilliardth |

quecto | q | 10^{-30} |
0.000 000 000 000 000 000 000 000 000 001 | nonillionth | quintillionth |

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

## How Many Watts in a Kilowatt and Kilowatts in a Watt

If you wonder how many watts (W) are there in a kilowatt (kW) and vice versa, just check the chart:

**1 kW = 1000W**

**1W = 10 ^{-3} kW**

This is a strictly mathematical 'issue' and can be even continued:

**1 kW = 1000W = 1 000 000 mW (milliwatt) = 10 ^{6} mW = 1 000 000 000 μW (microwatt) = 10^{9} μW**

**1W = 10 ^{-3} kW = 0.001 kW = 0.000001 MW**

It may look confusing, but multiplying large numbers using SI proxies is very simple:

**1 kW = 10 ^{3} W = 10^{3} * 10^{3} mW = 10^{3+3} mW = 10^{6} mW**

Or, just use a good calculator and be careful with typing the decimals.

## How Many Kilowatts in a Megawatt and Megawatts in a Kilowatt

Similarly, if you want to know how many kilowatts (kW) are there in a megawatt (MW) and vice versa, just check the chart:

**1 MW = 1 000 kW = 10 ^{3} kW = 10^{3} * 10^{3} W = 10^{3+3} W = 10^{6} W = 1 000 000 W**

**1 kW = 0.001 MW = 10 ^{-3} MW**

One kilowatt is a thousand watts, and one megawatt is a thousand kilowatts and/or a million watts.

If You want, You can easily express yottawatts using yoctowatts:

**1 YW = 10 ^{24} W = 10^{24} * 10^{24} yW = 10^{24+24} yW = 10^{48} yW**

Why would anybody in real-life electrical engineering use such large or small units, I don't know, but it is a good way of showing the actual scale from one end to another of the SI prefixes chart.

## How Many Watts in a Megawatt and Megawatts in a Watt

If you wonder how many watts (W) are there in a Megawatt (MW) nd vice versa, just check the chart:

**1 MW = 1 000 kW = 1 000 000 W = 10 ^{6} W**

**1W = 0.001 kW = 0.000001 MW = 10 ^{-6} MW**

So, one Megawatt is a million Watts, and Watt is a one-millionth of a Megawatt.

### How often does one use Megawatts (MW) in real life?

Well, the Rimac Nevera hypercar's maximum power output is 1914 HP, which is ~1.4 MW, and that is 1400000 Watts.

And that is a lot.

## Watts to Kilowatts and Kilowatts to Watts Conversion Calculator

To convert power expressed in Watts to kilowatts and kilowatts to Watts, feel free to use the following calculator:

## Power (W)P(W) = P(kW) * 1000 |
## Power (kW)P(kW) = P(W) / 1000 |

Power (kW): Power (W): |
Power (W): Power (kW): |

## Kilowatts to Megawatts and Megawatts to Kilowatts Conversion Calculator

To convert power expressed in Megawatts to kilowatts and kilowatts to Megawatts, feel free to use the following calculator:

## Power (kW)P(kW) = P(MW) * 1000 |
## Power (MW)P(MW) = P(kW) / 1000 |

Power (MW): Power (kW): |
Power (kW): Power (MW): |

## Short History of the Watt

The watt, a unit of power in the International System of Units (SI), has a fascinating history deeply intertwined with the evolution of science and industry.

Named after James Watt, the Scottish inventor who significantly improved the steam engine, the watt became a cornerstone in measuring power, a concept central to understanding and harnessing energy.

### The Origins of the Watt

The story of the Watt begins with James Watt's work in the late 18th century. Although Watt did not invent the steam engine, his enhancements made it much more efficient, transforming it into a key driver of the Industrial Revolution.

In honor of his contributions, the watt was officially adopted as a unit of power in 1882 during the International Electrical Congress. This was several decades after Watt's death, but his legacy lived on through this unit.

A watt is defined as one joule per second. It quantifies the rate of energy transfer. In practical terms, if a device is using one watt, it is consuming energy at a rate of one joule per second.

### Comparison with Horsepower

Horsepower is another unit of power, traditionally used to express the output of engines and motors. It originated from the Scottish engineer James Watt himself, who wanted a way to equate the power of his steam engines with that of draft horses, the workhorses of that era. One mechanical horsepower is equivalent to about 745.7 watts.

However, horsepower comes in various forms:

- Mechanical Horsepower (hp): Approximately 745.7 watts.
- Metric Horsepower (PS, CV): Slightly less than mechanical horsepower, at 735.5 watts.
- Electrical Horsepower: Commonly used in the electrical industry, it's equivalent to exactly 746 watts.

### The Watt in the Larger SI Context: Kilowatts and Megawatts

The watt scales up and down efficiently, making it ideal for various applications.

A kilowatt (kW) is 1,000 watts, often used to express the power of household appliances and small machinery. In larger scales, such as in power plants and electricity grids, power is measured in megawatts (MW), where one megawatt equals one million watts.

#### Kilowatts

A kilowatt represents a thousand watts of power. It is a common unit used in everyday life. For instance, a typical microwave might use about 1 kW of power. Residential solar panels also have their capacities expressed in kilowatts.

#### Megawatts

On a much larger scale, megawatts are used. One megawatt is equal to 1,000 kilowatts or one million watts. This unit is common in industrial applications and for measuring the output of power plants. For instance, a small power station might generate a few megawatts of power.

The watt, originating from the innovations of James Watt, has become a universal unit for measuring power. Its versatility, seen in its scalable forms like kilowatts and megawatts, and its comparison with traditional units like horsepower, highlight its importance in understanding and quantifying energy in both everyday life and large-scale industrial applications.

**Long Story Short:** Unit conversions, including W to kW to MW and back, are easy, just be sure to remember the right formulas, for example,

**1 MW = 1 000 kW = 1 000 000 W = 1 000 000 000 mW**

And don't forget to use the calculator, especially for very large or very small values.