Energy Converter
Convert energy between joules, kilojoules, calories, kilocalories, watt-hours, kilowatt-hours, and BTU. Enter a value, pick the From and To units, and the tool returns the converted amount. Free and runs in your browser.
What this calculator does
The Energy Converter estimates your result instantly from the values you enter, using standard science & engineering formulas. Convert energy between joules, kilojoules, calories, kilocalories, watt-hours, kilowatt-hours, and BTU. Enter a value, pick the From and To units, and the tool returns the converted amount. Free and runs in your browser. Calculations run in your browser, so nothing you type is sent to a server, and the output is an estimate rather than a certified or official figure.
Result
About Energy Converter
The Energy Converter changes an energy value from one unit to another. It supports joules (J), kilojoules (kJ), calories (cal), kilocalories (kcal), watt-hours (Wh), kilowatt-hours (kWh), and BTU.
Each value is converted to joules using fixed factors and then to the target unit, with the result rounded to six decimal places.
Formula & Mathematical Calculation
Converted Value = f(Energy value, From, To)
Calculated according to standard science formulas implemented in the calculator core.
Calculation Example
Converting 10 kcal to kJ:
10 × 4184 = 41840 J, then 41840 ÷ 1000 = 41.84 kJ
Key Benefits
- Converts across joules, kilojoules, calories, kilocalories, watt-hours, kilowatt-hours, and BTU
- Uses fixed joule-based factors, including 4.184 J per calorie and 1055.06 J per BTU
- Rounds the converted value to six decimal places
- Free, browser-based, and needs no sign-up
How to Use this Calculator
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Enter the energy value
Type the amount into the Energy value field, for example 10. -
Choose the From unit
Select the unit you are converting from, such as Kilocalorie (kcal). -
Choose the To unit and calculate
Select the target unit, such as Kilojoule (kJ), then select Calculate to see the converted value.
Assumptions & Limitations
What the calculation assumes
- Every value you enter is treated as an exact, known amount.
- Any rate or interval you enter is assumed to hold for the whole period unless the form asks for it separately.
- Results use standard published formulas and account only for the values entered above.
- Rounding is applied for display; the underlying calculation uses your full precision.
- Results are returned in the same units you enter, unless the tool states the output unit.
What it does not cover
- Energy Converter produces a calculated result for reference and learning, not a certified or official measurement.
- Real-world outcomes differ when tolerances, rounding rules or local standards apply.
- Definitions and standards vary by region and change over time; verify the convention that applies to your case.
- Figures are only as accurate as the inputs you supply — check them before acting on the result.
- For work where the result carries real consequences, confirm it against an authoritative source.
Frequently Asked Questions
Free to use, no account needed. Calculations run in your browser, so nothing you type is sent to a server. Results are estimates — how we build and check our calculators.