Kilojoules to Kilowatt-hours Converter

One kilojoule is exactly 1,000 joules, and the symbol is kJ. It is the joule multiple that food packaging commonly prints, with energy shown in kilojoules beside kilocalories, and chemistry uses it for reaction energies.

Nutrition panels, exercise machines and dietary advice report energy in kilojoules wherever the metric system is used. Materials and fuel data, such as energy content per kilogram, are tabulated in kilojoules as well.

The step from kilojoules to megajoules divides by exactly one thousand, so nothing is lost in the conversion. One kilocalorie equals 4.184 kilojoules, which is how the two columns on a food label correspond.

A reader who compares a kilojoule figure with a kilocalorie figure as though they were the same number will misjudge the energy by more than four times. The label's two columns state one amount in two units.

Kilojoules and kilocalories are the two energy columns on a food label, and the kilojoule figure is the larger number because one kilocalorie is 4.184 kilojoules. Megajoules take over where kilojoule figures become long, as they do for fuels.

The kilowatt-hour is the energy of one kilowatt sustained for one hour, and it is exactly 3.6 megajoules. Its symbol is kWh, and it equals 1,000 watt-hours.

Electricity bills, prepaid meter units, solar generation totals and battery or power-bank capacity are all measured in kilowatt-hours. Appliance consumption over time is compared in the same unit.

A kilowatt-hour is an amount of energy and a kilowatt is a rate, so the unit already contains the time element. Multiplying a kilowatt rating by hours of use gives kilowatt-hours directly.

Quoting a battery in kilowatt-hours when the label gives only amp-hours and a voltage skips a step, because the two must be multiplied first. A kilowatt-hour and a kilowatt are also not interchangeable.

The kilowatt-hour is the meter's accounting unit, the watt-hour is its one-thousandth for battery labels, and the joule and megajoule express the same energy in physics and fuel data. A meter reading is rarely converted into joules, but the two describe one amount.