Watts to Kilowatts (W to kW)

1 watt equals 0.001 kilowatts exactly.

How to convert watts to kilowatts

To convert watts to kilowatts, multiply the number of watts by 0.001. This factor is exact. To go the other way, multiply kilowatts by 1,000.

kilowatts = watts × 0.001

Example: 10 watts = 0.01 kilowatts.

Several different horsepower units exist. This site lists mechanical (745.7 W), metric (735.5 W) and electrical (746 W) horsepower separately.

About these units

Watt (W)

Metric (SI)Current unit

The SI unit of power: one joule per second. A typical LED bulb uses 5–10 W and a laptop 30–60 W.

Credit for the name goes to C. William Siemens, who proposed it in August 1882 in his presidential address to the British Association for the Advancement of Science. He chose it to honor James Watt, the Scottish inventor who in 1776 improved the Newcomen steam engine. An International Conference on Electric Units and Standards adopted Siemens' definition in London in October 1908 as the international watt. After the 1948 General Conference on Weights and Measures the unit was redefined in absolute terms, and in 1960 the 11th General Conference adopted it into the SI as the unit of power.

Today one watt is one joule per second, or equivalently one volt times one ampere. Orders-of-magnitude tables put an LED light bulb at about 7 W and an adult's basal metabolic rate at roughly 100 W. A 100 kg person climbing a 3 m ladder in 5 seconds works at about 600 W, while a laborer can sustain around 75 W over an eight-hour day. The watt measures a rate, so it says how fast energy is being used, not how much has been used in total.

The watt is the reference unit for power on this site.

Sources: Wikipedia: Watt; Wikipedia: Orders of magnitude (power)

Kilowatt (kW)

Metric (SI)Current unit

1,000 watts. Used for the power of motors, cars and household appliances.

A kilowatt is simply the watt with the SI prefix kilo, meaning a thousand, attached. The watt was adopted into the SI in 1960 and is small next to machinery, since an incandescent night light uses about 4 W, so the thousand-watt multiple suits engines, electric motors, tools and heaters. For readers used to older units, one kilowatt is roughly 1.34 horsepower.

Small electric heaters with a single element can use about 1 kW, and a domestic electric kettle or microwave oven draws a similar amount. The average household in the United States uses about 1 kW of electric power over time. On a clear midday near the equator, a square meter of Earth's surface receives about 1 kW of sunlight. Do not confuse the kilowatt with the kilowatt-hour on an electricity bill: the first is a rate, the second is the energy used by running one kilowatt for an hour, which equals 3,600,000 watt-seconds.

1 kilowatt = 1,000 watts (exactly).

Sources: Wikipedia: Kilowatt; Wikipedia: Orders of magnitude (power); BIPM: SI prefixes

Related conversions

See all power units.