Converted amount with unit and interpretation
The main result includes the target-unit label. The SI equivalent is in joules, and the table lists other supported energy representations. Conversion does not add an operating-time or efficiency assumption.
To estimate appliance energy use and cost from power, operating time, and tariff, use the Appliance Electricity Cost Calculator and follow its own input conventions.
The formula
Multiply by the source unit’s joule factor and divide by the target factor. Watt-hours include the duration unit; thermochemical calories and Btu IT use their explicitly named conventions.
Verified worked example
One kilowatt-hour equals 3,600,000 joules, or 3.6 megajoules. It also equals 1,000 watt-hours because the kilo prefix multiplies the unit by one thousand.
How to use this calculator
- Enter the energy quantity you already know.
- Choose matching source and destination units, checking cal versus kcal and the named Btu convention.
- Read the labeled result, equivalent joules, and conversion table.
Energy input conventions
Energy represents an amount of work or transferred heat. A watt-hour combines power with duration, so it is an energy unit even though its name contains watt. A kilowatt without the hour is a power unit and cannot be converted directly to energy without specifying elapsed time. The SI base-equivalent field here reports joules.
Interpreting converted amount with unit
Several historical calorie and British thermal unit conventions exist. This page explicitly selects the thermochemical calorie and International Table Btu, so a table based on another convention can differ slightly. A food-label Calorie generally refers to a kilocalorie, but confirm the label before choosing cal or kcal. This converter changes unit scale only; it does not estimate appliance efficiency, metabolic energy use, electricity tariffs, or heating-system output.
Assumptions & limitations
What this calculation assumes
- Calories use the thermochemical definition and Btu uses the International Table definition.
What to keep in mind
- No power-to-energy duration calculation; fixed thermochemical calorie and Btu IT conventions.
Common questions
Can I convert kW directly to kWh?
You need a duration. A constant power of 1 kW acting for one hour transfers 1 kWh; this page starts from an energy amount already supplied.
Which calorie does the tool use?
The thermochemical calorie, defined as 4.184 joules. Its kilocalorie is 4,184 joules. Other historical calorie definitions are not interchangeable.
Does the conversion account for efficiency?
No. Unit conversion preserves the same energy amount. Any difference between supplied and useful energy requires a separate efficiency model.
Sources & further reading
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