K

Alphabetical index

kelvin

Unit of measurement of thermodynamic temperature, symbol: K.

The symbol does not include the degree symbol °:
e.g. 1000 K, not 1000 °K.

kilo

Prefix for a multiple of 1000, symbol: k.

kilowatt-hour

The kilowatt-hour, symbol: kW h, is a unit of energy mostly used by utility companies.

As is the case with the hour, the kilowatt-hour is a non-SI unit but is accepted for use with the SI. The unit is formed by multiplying kilowatts by hours. For example a 2-kilowatt electric fire running for 3 hours, will use 6 kilowatt-hours of energy.

1 kilowatt-hour = 1 kilowatt × 3600 seconds

Since one watt is equal to one joule per second, it follows that:
1 kW h = 3600 kJ
1 kW h = 3.6 MJ

When metric units are formed by multiplying two individual units, a space or a hyphen is used to separate the names of the individual units.
e.g. kilowatt-hour or kilowatt hour (not kilowatthour).
For the corresponding symbols, a space or a half-high (centred) dot (⋅) is used to separate the symbols of the individual units.
e.g. kW h or kW⋅h (not kWh, or kW.h).