The kilojoule (kJ) equals 1,000 joules and is the standard unit for expressing food energy content and chemical reaction energies in countries using the metric system. Food labels in Australia, Europe, and many other regions display energy values in kilojoules alongside or instead of calories. One kilojoule equals approximately 238.8 calories or about 0.239 kilocalories.

The kilowatt-hour (kWh) equals 3,600,000 joules and is the standard billing unit for residential and commercial electricity consumption worldwide. Utility companies charge by the kilowatt-hour, and understanding this unit helps consumers evaluate appliance running costs and solar panel output. One kilowatt-hour represents the energy used by a 1,000-watt appliance running for one hour.