Energy Converter

Convert between joules, calories, kilowatt-hours, BTU, and electron volts energy units.

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1. Select the energy unit you want to convert from (joules, calories, kWh, BTU, or electron volts). 2. Enter the energy value in the input field. 3. Instantly see the equivalent energy expressed in all five supported units. 4. Use the results for comparing appliance efficiency, nutrition calculations, or physics problems. 5. Click copy next to any result to save the converted energy value to your clipboard.

About This Tool

The Energy Converter enables instant conversion between all major energy measurement units. Whether you are comparing energy consumption between appliances, converting food calorie values for scientific calculations, analyzing electricity costs, or working on physics problems, this tool provides precise conversions across five commonly used energy units.

Our converter supports joules (J) - the SI unit of energy, calories (cal) - familiar from nutrition and chemistry, kilowatt-hours (kWh) - the standard for electricity billing, British Thermal Units (BTU) - used in heating and cooling, and electron volts (eV) - essential in particle physics. Each conversion uses internationally recognized conversion factors for maximum accuracy.

Energy conversion is relevant in many fields. Homeowners compare energy costs between gas (BTU) and electric (kWh) appliances. Nutritionists convert between food calories and joules. Engineers calculate thermal efficiency across unit systems. Physicists switch between electron volts and joules. This converter serves all of these needs with a single, easy-to-use interface.

Formula / How It Works

1 J = 0.239006 cal = 2.7778e-7 kWh = 0.000947817 BTU = 6.242e+18 eV

Frequently Asked Questions

One thermochemical calorie equals exactly 4.184 joules. Note that the "calories" listed on food labels are actually kilocalories (kcal), where 1 kcal = 1,000 calories = 4,184 joules.
One kilowatt-hour (kWh) equals 3,600,000 joules (3.6 megajoules). This is because 1 kW = 1,000 watts = 1,000 joules per second, and one hour = 3,600 seconds. kWh is the standard unit for electricity billing.
A British Thermal Unit (BTU) is the amount of heat needed to raise one pound of water by one degree Fahrenheit. One BTU equals approximately 1,055.06 joules or about 252 calories. BTUs are commonly used to rate heating and cooling equipment.
An electron volt (eV) is the energy gained by an electron moving through an electric potential difference of one volt. It equals approximately 1.602 x 10^-19 joules. It is used in particle physics and quantum mechanics where joules would be impractically small numbers.
Gas is typically measured in BTUs or therms (1 therm = 100,000 BTU) and electricity in kWh. To compare: 1 kWh = 3,412 BTU. Divide the BTU rating of gas by 3,412 to get the kWh equivalent, then compare costs using your utility rates.

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