Energy Converter

Convert between joules, calories, and kilowatt-hours using the exact thermochemical calorie definition.

Works for any combination of the units above -- every value converts through the same verified base-unit math used on the individual pages.

How Energy Units Relate

Energy units here reduce to the joule, the SI unit of energy. The calorie traces back to the historical definition of heating water, standardized today as exactly 4.184 joules; the kilowatt-hour is a practical billing unit equal to running one kilowatt of power for one hour (3,600,000 joules).

All Energy Converters

Each of these has its own page with the exact formula, a reference table, and answers to common questions.

Joule to Calorie Calorie to Joule Kilowatt-hour to Joule

Cedrick Reese

Ready Utilities was founded by Cedrick Reese, a retired veteran and web developer who enjoys building free, user-friendly online tools that simplify everyday tasks. His journey began in the early 2000s with affiliate marketing and niche site development, which grew into a passion for creating practical digital utilities and calculators. After retiring, he earned a Computer Systems Technician certificate from UEI College, completed Electro-Mechanical Technologies at Tulsa Welding School, and finished the Carpentry program at Florida State College at Jacksonville. Today, he combines his technical background and craftsmanship by building furniture using traditional woodworking methods, gardening, and developing helpful online tools for users worldwide.