Free Online Energy Converter
An energy tool maps a value across joules, kilojoules, calories, kilocalories, Wh, kWh, BTU and electronvolts using the joule as the SI pivot.
Your data is processed entirely in your browser and never sent to any server.
How to Use This Converter
- Pick the input unit in From.
- Pick the output unit in To.
- Type the energy value; the converted result and factor display.
- Tap swap to reverse direction.
What Is an Energy Converter?
Energy is the same physical quantity behind food labels, electricity bills, heating specs and atomic physics, just measured in radically different scales. The SI unit is the joule. Nutrition uses kilocalories (1 kcal = 4184 J), often labelled simply 'Calories' with a capital C. Utility bills use kilowatt-hours (1 kWh = 3.6 MJ). HVAC and refrigeration use BTU (1 BTU ≈ 1055.06 J). Particle physics uses electronvolts (1 eV ≈ 1.602 × 10⁻¹⁹ J).
This matters whenever you compare across domains. A 500 kcal meal is 2.1 MJ. A 60 Wh laptop battery holds 216 kJ. A 12,000 BTU air conditioner runs at 3.52 kW.
The tool normalises every input to joules and converts to the chosen output unit, showing the ratio so you can sanity-check the result.
Frequently Asked Questions
How many joules in a calorie?
What is a BTU?
kWh to joules?
Published by the WeGotEveryTool team. We build and test every tool in-house and update pages when the underlying spec, formula, or recommendation changes.
Reviewed: May 2026. Disclaimer: this tool is provided as-is for general informational use. For decisions with material consequences (medical, legal, financial, security) verify results against a qualified professional source.
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