Can I control the decimal precision of the conversion results?

Yes, the calculator lets you set decimal precision from 0 to 12 places, depending on your needs.

Can I do multiple conversions at once?

Yes, the calculator displays equivalent values in all standard energy units instantly, so you can see conversions across different units at the same time.

How does the ‘One-click unit swap’ feature help?

The 'One-click unit swap' feature instantly reverses the source and target units. This is helpful if you want to double-check your conversions or switch the direction of the conversion without re-entering data.

Can I convert both metric and imperial energy units?

Yes, you can convert both metric units, like joules and kilojoules, and imperial units, like BTU and foot-pounds, with our energy converter.

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Updated on September 1, 2025

About Our Energy Unit Conversion Calculator

Written By

Nadiba Rahman

Reviewed by

Mrinmoy Roy

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Our energy conversion calculator provides fast and reliable conversions across 18 different energy units, like joules, calories, BTUs, kilowatt-hours, electronvolts, and more. It features real-time results, adjustable settings, and a handy history tracker, making your conversions smoother and faster. In this guide, I’ll explain how energy conversions work and how our converter can save you time and effort.

What is Energy?

Energy is the capacity to do work. According to the law of conservation of energy, energy cannot be created or destroyed; it can only be converted from one form to another.

The standard unit of energy is the joule (J). Depending on the situation, energy is also measured in kilowatt-hours (kWh), calories, British thermal units (BTUs), and more.

Energy comes in different forms, such as mechanical energy (motion of objects), thermal energy (heat), chemical energy (stored in bonds), electrical energy (movement of electrons), nuclear energy (stored in the nucleus of atoms), potential energy (stored energy based on an object’s position, like gravitational or elastic energy), and kinetic energy (energy of motion).There are also several natural sources of energy, such as:

Solar Energy: Energy from the sun.
Wind Energy: Energy from moving air.
Hydroelectric Energy: Energy from moving water.
Biomass Energy: Energy from organic materials.

Conversion Units of Our Energy Converter

Here are the 18 units you can convert using our energy conversion calculator:

British Thermal Unit (BTU): A BTU is the energy to heat one pound of water by one degree Fahrenheit. It’s used mostly in the United States for heating and cooling systems.
Calorie (cal): A calorie is the energy to heat one gram of water by one degree Celsius. It’s commonly used in food labeling.
Erg: An erg is a small energy unit used in physics. One erg equals 1 × 10⁻⁷ joules.
Electronvolt (eV): An electronvolt measures the energy of an electron when moving through a one-volt potential. It’s used in particle and atomic physics.
Exajoule (EJ): An exajoule is a very large unit of energy, equal to one quintillion joules (1,000,000,000,000,000 J).
Foot-pound (ft-lb): It represents the energy required to move one pound a distance of one foot. It’s often used in mechanics and engineering.
Gigajoule (GJ): A gigajoule is one billion joules (1 GJ = 10⁹ joules). It is commonly used in large-scale energy applications.
Gigawatt-hour (GWh): A gigawatt-hour is a unit of energy equivalent to one gigawatt of power used for one hour. It measures electricity generation and use.
Joule (J): The joule is the SI unit of energy. It represents the energy needed to move one coulomb of electric charge through a potential difference of one volt.
Kilocalorie (kcal): A kilocalorie, also called a large calorie, is 1,000 calories. It measures the energy in food.
Kilojoule (kJ): A kilojoule is 1,000 joules. It’s used for nutrition and scientific work.
Megajoule (MJ): A megajoule is one million joules (1,000,000 J). It’s used in the energy and heating fields.
Megawatt-hour (MWh): It’s equivalent to one megawatt of power consumed over one hour. It is frequently used in electricity generation and consumption.
Natural Gas Low Heating Value (NG LHV): It measures the heat released by burning natural gas but excludes the energy from vaporizing water.
Newton-meter (N·m): It is defined as the energy used to move an object one meter with a force of one newton. It measures energy in the metric system.
Therm: A therm is a unit of heat energy used in natural gas. One therm equals 100,000 BTUs.
Watt-hour (Wh): It’s equivalent to one watt of power used for one hour. It is commonly used to measure the energy consumed by electrical devices.
Watt-second (Ws): A watt-second is the amount of energy used when one watt of power is consumed for one second. It’s used in electrical and scientific contexts.

How to Use Our Energy Conversion Calculator?

To use our energy conversion calculator, follow the easy steps below:

Select the energy units you want to convert from and to.
As soon as you choose the units, a real-time formula preview appears that helps you understand the conversion between the selected units.
Input the energy value in the source field.
The converted result will appear immediately in the target unit. You can even copy the result instantly with our one-click copy option.

Features of Our Energy Conversion Calculator

Our energy conversion calculator includes powerful features to handle even the most precise energy conversions. You can access all these features from the settings menu. Here’s how each feature supports your work:

Real-time Multi-unit Conversion

Energy values often need to be viewed in multiple units. Our calculator displays the equivalent values in all standard energy units instantly, so you don’t have to convert each unit manually.

For instance, if you enter 150 joules, it automatically shows kilocalories, BTUs, and more, helping you cross-check data and share results seamlessly.

Flexible Decimal Precision

Even a small error in energy conversion can cause incorrect calculations or analysis. That’s why our energy conversion calculator lets you set your desired level of decimal precision.

By default, results are displayed up to 6 decimal places, but you can adjust this to any value between 0 to 12 decimal places in the settings menu. This flexibility ensures you get the exact level of precision you need for your project or analysis.

Rounding Mode Control

When working with energy conversions in critical applications, even small differences can impact heating calculations, efficiency assessments, or system sizing accuracy. That’s why our calculator includes rounding mode control.

You can choose to round up, round down, or turn off rounding completely. This ensures your converted energy values meet your project’s exact requirements and reduces the risk of calculation errors.

Multiple Number Format

Energy can be as small as nanojoules or as large as terajoules. To make these numbers easier to read and work with, our calculator lets you choose from three formats:

Standard Decimal (like 5,000,000,000 J)
Scientific Notation (like 5.0e+9)
Engineering Format (like 5.0 × 10^9)

For example, converting 5 gigajoules can be displayed as 5,000,000,000 J (Standard Decimal), 5.0e+9 (Scientific), or 5.0 × 10^9 (Engineering), making results easier to understand and communicate depending on your project.

Thousand Separators Toggle

Energy values can get very large and hard to read, especially in industrial settings. Our toggle lets you turn on thousand separators, making big numbers clearer and easier to review. For example, instead of seeing 12345678 joules, you’ll see 12,345,678 J.

One-click Unit Swap

When checking energy conversions, it’s often helpful to see the values both ways, for instance, converting calories to joules and then back to double-check your work. Our one-click unit swap quickly reverses the input and output units with just one click, making your process faster and more accurate.

Clickable and Auto-Saved Conversion History

When working with energy conversions, it’s easy to lose track of your past results. Our calculator automatically saves your last 10 conversions, even if you refresh or close your browser, so you can quickly find and reuse them without retyping.

Simply open the History tab and click on any previous entry to load it right away. This makes your work faster, more organized, and error-free.

Energy Conversion Chart

Click the button below to download the energy conversion chart. This chart provides conversion factors for all your energy calculations.

3 Examples of Conversion With Our Energy Converter

To convert energy units accurately, you need to know the source unit, the target unit, and the correct conversion factor (you can find these in the Energy Conversion Chart above). The formula is simple:Converted Value = Conversion Factor × Value of Source UnitHere are three quick examples:

Joules (J) to Kilocalories (kcal) Conversion

To convert joules to kilocalories, multiply the joule value by the conversion factor 0.000239. For example, to convert 1000 joules to kilocalories:

1000 × 0.000239 = 0.239006 kilocalories

Conversion between Joules and Kilocalories

For reverse conversion (kilocalories to joules), multiply the kilocalorie value by 4184.

British Thermal Units (BTU) to Watt-hours (Wh) Conversion

To convert BTUs to watt-hours, multiply the BTU value by 0.293072. For example, to convert 500 BTUs to watt-hours:

500 × 0.293072 = 146.536 watt-hours

Conversion between British Thermal Units and Watt-hours

For reverse conversion (watt-hours to BTUs), multiply the watt-hour value by 3.412128.

Megajoules (MJ) to Gigajoules (GJ) Conversion

To convert megajoules to gigajoules, multiply the megajoule value by 0.001. For example, to convert 4300 MJ to GJ:

4300 × 0.001 = 4.3 GJ

Conversion between Megajoules and Gigajoules

For reverse conversion (gigajoules to megajoules), multiply the gigajoule value by 1000.

Conclusion

Easily convert between different energy units with our smart and user-friendly energy conversion calculator. Whether you're dealing with joules, BTUs, calories, or kilowatt-hours, this tool offers accurate results, real-time formulas, and flexible display options. Try it out and make your energy conversions smooth, fast, and error-free with our reliable conversion tool.

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