Energy Unit Conversion

Enter a value in any unit below to instantly convert between SI, metric, imperial and other energy units.

S.I. Units

Joule (J)

J

Kilojoule (kJ)

kJ

Metric Units

Calorie (cal)

cal

Kilocalorie (kcal)

kcal

Imperial Units

British Thermal Unit (BTU)

BTU

Other Units

Kilowatt-hour (kWh)

kWh

Horsepower-hour (hph)

hph

Kilogram force meter (kgf·m)

kgf·m

Pound-force foot (lbf·ft)

ft-lbf

Unit Conversion Relations

1 kJ = 0.24 kcal = 0.95 BTU
1 kWh = 1.34 hph = 3600 kJ
1 kgf·m = 9.81 N·m = 7.23 ft-lbf = 9.81 J

FAQ

What is the difference between energy and power?
Energy is the capacity to do work, measured in joules (J) or kilowatt-hours (kWh). Power is the rate at which energy is used or transferred, measured in watts (W) or kilowatts (kW). Energy = Power × Time.
Why are there so many different energy units?
Different industries and applications use different units. Joules are the SI standard, calories are used in nutrition and chemistry, BTUs in heating/cooling, kWh for electricity billing, and horsepower-hours in mechanical systems. Each unit evolved for specific practical needs.
How do I convert between mechanical and thermal energy units?
Use the mechanical equivalent of heat: 1 calorie = 4.184 joules. For example, 1 BTU = 1055 J, and 1 kWh = 3.6 MJ. The calculator handles these conversions automatically using established conversion factors.
What are typical energy consumption values?
A typical home uses 10-30 kWh/day, a car engine produces about 100-300 HP (75-225 kW), and human daily food intake is about 2000 kcal (8.4 MJ). These values help put energy measurements in perspective.
How accurate are energy unit conversions?
The conversions use internationally accepted conversion factors and are highly accurate. For example, 1 kWh = exactly 3,600,000 J. The calculator maintains precision suitable for engineering, scientific, and commercial applications.
What are common applications for energy calculations?
Energy calculations are used in electrical engineering (power consumption), mechanical engineering (work done), HVAC systems (heating/cooling loads), nutrition (caloric content), and renewable energy systems (solar, wind output). They're essential for efficiency analysis and cost calculations.