Energy Units Conversion Calculator

Energy Unit Converter

Enter a value in any field to convert between all units

1000 J

1 kJ

1 BTU

1 kcal

1 kWh

Joule J

Kilojoule kJ

Megajoule MJ

Gigajoule GJ

Calorie cal

Kilocalorie kcal

BTU BTU

Watt-hour Wh

Kilowatt-hour kWh

Electron volt eV

Foot-pound ft⋅lbf

Therm therm

Show scientific notation

Energy Comparison

Visual representation of energy magnitude

Gigajoule (GJ) Megajoule (MJ) Kilojoule (kJ) Joule (J) Calorie (cal) BTU kWh Wh

No value entered

Energy Conversion Formulas

1 BTU = 1055.06 J

1 cal = 4.184 J

1 kWh = 3.6 MJ

1 therm = 105.5 MJ

Note: The visualization shows relative magnitude on a logarithmic scale.

Advanced Energy Calculators

Professional tools for energy analysis and calculations

Energy Density Calculator

Energy:

Mass/Volume:

Density:

Energy Cost Calculator

Energy:

Rate: $/unit

Total Cost:

Heat Capacity Calculator

Mass (kg):

Specific Heat:

ΔT (K):

Energy (J):

Formula: Q = m × c × ΔT

Energy Efficiency Calculator

Useful Energy:

Total Energy:

Efficiency:

Formula: η = (Useful Energy / Total Energy) × 100%

Fuel Energy Content Database

Gasoline

34.2

MJ/L

Diesel

38.6

MJ/L

Natural Gas

37.5

MJ/m³

Coal

24-35

MJ/kg

Wood

15-20

MJ/kg

Hydrogen

120

MJ/kg

Propane

25.3

MJ/L

Ethanol

21.2

MJ/L

Energy Scale Visualization

Compare different energy magnitudes across common applications

Energy Range	Example Applications	Typical Units
1 J - 1 kJ	Small electronic operations, sensor readings	J
1 kJ - 1 MJ	Food calories, small device batteries	kJ, kcal
1 MJ - 1 GJ	Household daily energy, car fuel tank	MJ, kWh
1 GJ - 1 TJ	Building heating systems, industrial processes	GJ, MMBtu
1 TJ - 1 PJ	Power plant daily output, city energy consumption	TJ
1 PJ+	National energy consumption, major industrial facilities	PJ, TWh

Energy Conversion Examples

Common Energy Equivalents

1 kWh = 3.6 MJ = 3,412 BTU = 860 kcal
1 gallon gasoline ≈ 129 MJ = 36 kWh = 121,000 BTU
1 ton TNT = 4.184 GJ = 1,162 kWh = 4 million BTU
Human daily food ≈ 8-10 MJ = 2,000-2,500 kcal
Lightning bolt ≈ 1-5 GJ = 280-1,400 kWh
1 cubic meter natural gas ≈ 37.5 MJ = 10.4 kWh

Energy Storage Comparison

Storage Method	Energy Density	Typical Use
Lithium-ion Battery	0.4-0.9 MJ/kg	Electronics, EVs
Lead-acid Battery	0.14 MJ/kg	Cars, UPS systems
Compressed Air	0.02-0.2 MJ/kg	Grid storage
Pumped Hydro	0.001-0.002 MJ/kg	Grid storage
Flywheel	0.01-0.5 MJ/kg	Grid stabilization

Energy in Real-World Applications

Understanding energy units in various fields and industries

Thermodynamics & HVAC

In thermodynamics and HVAC systems, energy is measured in various units:

Building heating: 10-100 GJ per year for residential homes
Air conditioning: 1-5 kWh per hour for residential units
Industrial heating: 100 MJ - 10 GJ per day
Refrigeration systems: 5-50 kWh per day

BTU and kWh are commonly used for HVAC calculations, while industrial processes often use MJ or GJ.

Industrial Processes

Industrial applications involve significant energy consumption:

Steel production: 18-25 GJ per ton of steel
Aluminum smelting: 45-55 GJ per ton of aluminum
Cement production: 3-6 GJ per ton of cement
Chemical processing: 1-100 GJ per ton depending on product
Paper manufacturing: 10-30 GJ per ton of paper

Energy efficiency calculations are critical for cost optimization and environmental compliance.

Transportation

Transportation energy is typically measured in fuel equivalents:

Gasoline car: 2-4 MJ per km (highway driving)
Electric vehicle: 0.6-1.2 MJ per km (150-300 Wh/km)
Diesel truck: 8-15 MJ per km depending on load
Commercial aircraft: 3-4 MJ per passenger-km
High-speed rail: 0.5-1 MJ per passenger-km

Understanding energy content helps in fuel economy calculations and emission assessments.

Residential Energy

Household energy usage patterns:

Daily household consumption: 20-50 kWh (70-180 MJ)
Water heating: 3-5 kWh per day (10-18 MJ)
Cooking: 1-3 kWh per day (3.6-10.8 MJ)
Lighting: 0.5-2 kWh per day (1.8-7.2 MJ)
Space heating: 50-200 kWh per day in winter (180-720 MJ)

Energy audits use these conversions to identify efficiency opportunities and size renewable systems.

Food & Nutrition

Food energy is typically measured in calories:

Daily human energy intake: 8-12 MJ (2000-3000 kcal)
Carbohydrates: 17 kJ/g (4 kcal/g)
Proteins: 17 kJ/g (4 kcal/g)
Fats: 38 kJ/g (9 kcal/g)
Alcohol: 29 kJ/g (7 kcal/g)

Nutritional analysis requires accurate conversion between calories and joules for metabolic calculations.

Renewable Energy

Renewable energy systems use various energy measurements:

Solar irradiance: 3-7 kWh/m² per day (10-25 MJ/m²)
Wind energy: 2-4 MWh per MWh capacity per day
Biomass energy content: 15-20 MJ/kg for wood
Hydroelectric: Energy = mgh (gravitational potential)
Geothermal: 50-150 MJ/m³ of hot water

Energy calculations help determine feasibility and sizing of renewable energy installations.

About Energy Units

Energy is the capacity to do work or produce heat. The SI unit of energy is the joule (J), but many other units are used in different fields and regions.

Common energy units and their applications:

Joule (J): SI base unit - Used in scientific calculations, physics
Kilojoule (kJ): 1000 J - Used in nutrition, small-scale energy calculations
Megajoule (MJ): 10⁶ J - Used in industrial processes, fuel energy content
Gigajoule (GJ): 10⁹ J - Used in large industrial processes, building energy
Calorie (cal): 4.184 J - Used in chemistry, small-scale measurements
Kilocalorie (kcal): 4,184 J - Used in nutrition, food energy content
BTU: 1,055.06 J - Used in HVAC, energy industries (especially US)
Watt-hour (Wh): 3,600 J - Used in electrical energy measurements
Kilowatt-hour (kWh): 3.6 MJ - Used in electrical utility billing
Therm: 105.5 MJ - Used in natural gas industry
Electron volt (eV): 1.602 × 10^-19 J - Used in atomic physics
Foot-pound (ft⋅lbf): 1.356 J - Used in mechanical engineering

Understanding these units and their conversions is essential for energy analysis, efficiency calculations, and engineering design.