Energy Converter

Energy Converter - Joules, Calories, kWh, BTU | Tuttilo

Convert between all common energy and work units instantly.

Enter your value in any supported energy unit and select from a comprehensive range including Joules, kilojoules, calories, kilocalories, watt-hours, kilowatt-hours, BTUs, and electron volts. The tool instantly calculates equivalent values across all units simultaneously, letting you compare electrical energy (kWh), heat energy (BTU), nutritional energy (kcal), and atomic-scale energy (eV) side by side. All conversions happen directly in your browser using precise conversion factors, ensuring your energy data never leaves your device.

Physics students use this when solving thermodynamics problems that require converting between mechanical work in Joules and heat in calories. Electrical engineers calculate battery capacity by converting watt-hours to Joules for circuit analysis. Nutritionists translate food energy from kilocalories to kilojoules when working with international dietary standards. HVAC technicians convert between BTUs and kilowatts when sizing heating and cooling systems for buildings.

Remember that calories in nutrition labels are actually kilocalories (kcal) — one food calorie equals 1000 small calories. When working with batteries, note that watt-hours depend on voltage, so a 5000mAh power bank at 3.7V delivers about 18.5Wh of energy. For scientific accuracy, use Joules as your reference unit since it's the SI standard. When converting electron volts, keep in mind this unit is primarily used at atomic and molecular scales — one eV equals approximately 1.602×10⁻¹⁹ Joules.

All processing happens directly in your browser. Your files never leave your device — no server uploads, no cloud storage, no data retention. The tool works offline once loaded, requires no registration, and is completely free with no usage limits.