Energy Conversion Calculator

Free Online Energy Conversion Calculator

Effortlessly convert between energy units like watt-hours (Wh), kilowatt-hours (kWh), megawatt-hours (MWh), BTUs, joules (J), calories, and electronvolts (eV) with our intuitive calculator. Perfect for engineers, students, and energy enthusiasts, this tool provides instant, accurate conversions with a history log and no sign-up required.

Energy Unit Converter

Conversion History

How to Use the Energy Conversion Calculator

Our Energy Conversion Calculator simplifies converting between various energy units, from watt-hours to electronvolts. Follow these steps to get accurate results:

  1. Enter a Value: Input a number in any of the provided unit fields (e.g., kWh, Joules, BTU). Use decimal points for precision if needed.
  2. Click Convert: Press the "Convert" button to instantly calculate the equivalent values in all other units.
  3. Review Results: View the converted values displayed in a clear, organized grid below the input fields.
  4. Track History: Your conversions are logged in the history section, with an option to copy results to your clipboard.
  5. Clear Inputs: Use the "Clear" button to reset all fields and start a new conversion.
  6. Copy Results: Click the copy icon next to any result in the history log to copy it to your clipboard for easy sharing or documentation.

Note: Only one input field should contain a value at a time. If multiple fields are filled, the first non-empty field (from top to bottom) will be used for conversion.

Frequently Asked Questions (FAQ)
What is an energy conversion calculator, and who can use it?
An energy conversion calculator transforms energy values between different units, such as joules (J), kilowatt-hours (kWh), BTUs, and electronvolts (eV). It’s invaluable for engineers calculating power consumption, students studying physics, homeowners analyzing energy bills, or researchers working with subatomic particles. This tool ensures quick, accurate conversions for professional and educational use.
Which energy units are supported by this calculator?
The calculator supports a wide range of units: watt-hour (Wh), kilowatt-hour (kWh), megawatt-hour (MWh), BTU (IT), kiloBTU (kBTU), joules (J), kilojoules (kJ), megajoules (MJ), gigajoules (GJ), calories (cal), kilocalories (kcal), electronvolts (eV), kiloelectronvolts (keV), megaelectronvolts (MeV), and gigaelectronvolts (GeV). This covers applications from everyday energy use to scientific research.
How accurate are the conversions?
Conversions are based on standard scientific constants (e.g., 1 kWh = 3,600,000 J, 1 BTU = 1055.06 J) and are accurate to several decimal places. Results are rounded to 6 decimal places for readability, but you can copy raw values from the history log for higher precision if needed.
Can I use this calculator offline?
The calculator requires an active internet connection to load its interface and scripts. Once loaded, it functions offline as it performs calculations locally in your browser. However, features like external links or updates won’t work without connectivity.
How does the conversion history feature work?
Each time you convert a value, the input and all resulting conversions are saved in the history log below the calculator. You can view past calculations, copy individual results to your clipboard, or clear the history using the "Clear" button. History is stored in your browser’s local storage and persists until you clear it or your browser data.
What’s the difference between calories and kilocalories?
A calorie (cal) is the energy needed to raise 1 gram of water by 1°C, while a kilocalorie (kcal) equals 1,000 calories. In nutrition, “calories” on food labels typically refer to kilocalories. For example, 1 kcal = 4,184 J, while 1 cal = 4.184 J. Our calculator clearly distinguishes between these units for accurate conversions.
Why include electronvolts (eV) in an energy calculator?
Electronvolts (eV) are commonly used in physics to measure energy at atomic and subatomic scales (1 eV ≈ 1.602 × 10⁻¹⁹ J). Including eV, keV, MeV, and GeV makes the calculator useful for researchers and students in fields like particle physics or quantum mechanics, bridging macroscopic and microscopic energy scales.
Is this calculator accessible for users with disabilities?
Yes, the calculator is designed with accessibility in mind. It features high-contrast visuals, clear typography, and keyboard-navigable inputs and buttons (use Tab and Enter keys). Labels are associated with inputs for screen reader compatibility. We welcome feedback to further enhance accessibility.
Can I use this for real-world applications like energy bills?
Absolutely! Convert kWh from your energy bill to joules or BTUs to understand consumption in different contexts, such as comparing appliance efficiency or calculating heating costs. The calculator’s precision and history log make it practical for both household and professional energy analysis.

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About Our Energy Conversion Calculator

Energy calculations can be complex, but our Energy Conversion Calculator makes them simple and accessible. Whether you’re an engineer sizing a solar panel system, a student solving physics problems, or a homeowner comparing energy usage, this tool delivers instant, reliable conversions across 15 units, from watt-hours to gigaelectronvolts.

Built with precision and user experience in mind, the calculator features a clean interface, a conversion history log, and copy-to-clipboard functionality. No downloads or accounts are needed—everything runs securely in your browser. With accessibility features like keyboard navigation and high-contrast design, it’s suitable for all users. Start converting energy units today and streamline your calculations with confidence.