Joules, calories, kilowatt-hours and electronvolts.
Open the Energy converter →One of 23 unit converters in the ABC Chemistry Calculator Suite, alongside 44 chemistry, physics and maths tools. Nothing is behind a login and no value you type is sent anywhere — the conversion runs in your own browser.
The link above opens the suite with the Energy set already selected.
Any unit here converts to any other in one step — for example J to kJ, J to cal, J to kcal. Values are converted in your browser; nothing is sent to a server.