Online Energy Unit Converter

Instantly convert between Joules, Calories, Kilowatt-hours, BTU, Electron Volts, and more. Perfect for students, engineers, fitness enthusiasts, and anyone working with energy measurements.

From

Quick Reference

Common Conversions

1 cal = 4.184 J

1 kWh = 3,600,000 J

1 BTU = 1,055.06 J

1 kcal = 4.184 kJ

Common Uses

Nutrition & calorie tracking (kcal ↔ kJ)
Electricity bill calculations (kWh ↔ J)
HVAC & heating system sizing (BTU ↔ kWh)
Physics & chemistry homework
Engineering thermodynamics calculations

About Energy Converter

Convert between all common energy units used in physics, engineering, nutrition, and everyday life. All conversions happen instantly in your browser — no data is sent to any server.

Features

10 energy units: J, kJ, cal, kcal, Wh, kWh, BTU, eV, ft·lbf, erg
Pure client-side — your data never leaves your device
Real-time bidirectional conversion
One-click swap to reverse units
Copy result to clipboard instantly
Shows conversion formula for transparency