Energy Unit Converter
The Energy Unit Converter converts between 20+ energy units including joules, kWh, BTU, calories, electronvolts, and fossil fuel equivalents (toe, boe). It generates a complete conversion table, provides power unit conversion (watts, hp, BTU/h), and calculates energy-to-time relationships — with instant interactive results AI cannot replicate. Free, no signup.
3,600,000 J
Formula: 1 kWh = 3,600,000 J
Full Conversion Table
SI Units
Electrical
Thermal
Food
Nuclear/Atomic
Mechanical
Fossil Fuel Equivalents
Power Conversion
1.341021859 hp
Formula: 1 kW = 1.341021859 hp
Energy ↔ Time
10 hours
Formula: 100 Wh ÷ 10 W
Common Equivalences
- 1 kWh = 3,600,000 J
- 1 kWh = 860 kcal
- 1 BTU = 1,055 J
- 1 cal = 4.184 J
- 1 eV = 1.602 × 10⁻¹⁹ J
- 1 toe = 41.868 GJ
- 1 hp·h = 2,684,520 J
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What is an Energy Unit Converter?
An Energy Unit Converter translates between different units of energy measurement across scientific, engineering, and everyday domains. Energy — the capacity to do work — is measured in joules (SI), but practically expressed in kilowatt-hours (electrical billing), BTU (HVAC), calories (food/chemistry), electronvolts (particle physics), and tonnes of oil equivalent (energy policy). All conversions pass through joules: 1 kWh = 3.6 × 10⁶ J, 1 BTU = 1055.06 J, 1 cal = 4.184 J, 1 eV = 1.602 × 10⁻¹⁹ J. The converter also handles power units and energy-time relationships.
How to Use This Converter
- Enter the energy value you want to convert
- Select the source unit from 20+ options across 7 categories
- Select the target unit or view the complete conversion table for all units
- Use the power converter tab for watts, kilowatts, horsepower, and BTU/hour
- Calculate energy-to-time relationships (e.g., how long a battery lasts at a given power)
Frequently Asked Questions
How do I convert kWh to joules?
Multiply by 3,600,000 (3.6 × 10⁶). One kilowatt-hour equals the energy of 1000 watts sustained for 3600 seconds: 1 kWh = 1000 W × 3600 s = 3,600,000 J = 3.6 MJ. For example, a typical US household uses about 30 kWh/day = 108,000,000 J = 108 MJ.
What is the difference between a calorie and a food Calorie?
A 'small calorie' (cal) is the energy to raise 1 gram of water by 1°C = 4.184 joules. A 'food Calorie' (Cal, capitalized) or kilocalorie (kcal) equals 1000 small calories = 4184 joules. When nutrition labels say '200 Calories,' they mean 200 kcal = 836,800 J. The confusing naming convention persists from 19th-century chemistry.
What is a tonne of oil equivalent (toe)?
One tonne of oil equivalent (toe) = 41.868 GJ = 11,630 kWh, representing the energy released by burning one metric tonne of crude oil. It's used in energy policy to compare different fuel sources: 1 toe ≈ 1.43 tonnes of coal ≈ 1111 m³ of natural gas. Global primary energy consumption is about 14,000 Mtoe (megatonnes of oil equivalent) per year.
How many electronvolts are in a joule?
One joule equals approximately 6.242 × 10¹⁸ electronvolts (eV). Conversely, 1 eV = 1.602 × 10⁻¹⁹ J — the energy gained by an electron accelerated through 1 volt. Particle physics uses MeV (10⁶ eV) and GeV (10⁹ eV): a proton's rest mass energy is 938.3 MeV, and the Higgs boson has a mass-energy of 125.1 GeV.