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Energy Converter — 65+ Units Worldwide | Joules, kWh, BTU, Calories, eV | ASLI FORM

Energy Converter

Convert between 65+ energy units used worldwide with scientific precision. Select a unit group to filter the options.

Showing: All Energy Units (65 units)
Conversion Formula
1 kilowatt-hour = 3,600,000 joules

Common Energy Conversions

Quick reference table
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Understanding Energy

Energy is the quantitative property that is transferred to a body or physical system, recognizable in the performance of work and in the form of heat and light. The SI unit of energy is the Joule (J), named after James Prescott Joule. Energy exists in many forms and is measured using different units depending on the field, scale, and regional conventions.

Our converter supports every major energy unit system used globally — from the International System of Units (SI) used in physics, to kilowatt-hours used in electricity billing, BTUs used in HVAC systems, calories used in nutrition and chemistry, electronvolts used in particle physics, and industrial units like tons of oil equivalent and TNT equivalents.

Electrical Energy

Measured in watt-hours and kilowatt-hours. Used in electricity billing and power engineering.

Thermal Energy

Heat energy measured in BTUs, calories, and Joules. Used in HVAC and thermodynamics.

Atomic & Nuclear

Measured in electronvolts (eV), MeV, GeV. Used in particle physics and nuclear energy.

Food Energy

Measured in Calories (kcal) and kilojoules. Used in nutrition labeling worldwide.

Industrial Units

TOE, BOE, therms. Used in oil & gas industry and energy economics.

Explosives

TNT equivalents. Used in military, mining, and asteroid impact calculations.

Mechanical

Foot-pounds, horsepower-hours. Used in mechanical engineering and automotive.

Scientific Units

Joules, ergs, Hartree. Used in physics research and scientific calculations.

How to Use This Energy Converter

Our energy converter is engineered for precision, speed, and ease of use across all 65+ units. Follow these steps to get accurate conversions instantly.

  • Select a Unit Group Choose from 9 groups using the sidebar to filter units by category (SI, Electrical, Thermal, Atomic, etc.).
  • Choose Source Unit Pick the energy unit you want to convert from in the first dropdown.
  • Choose Target Unit Select the energy unit you want to convert to in the second dropdown.
  • Enter Value Type your number — the result appears instantly with 10-digit precision.
  • Swap Units Click the swap button to instantly reverse the conversion direction.
  • Review Formula The exact conversion factor and formula are displayed for verification.

Why Scientists Choose ASLI FORM

Built with scientific precision and premium design, our energy converter meets the demands of researchers, engineers, and professionals across every field.

  • Scientific Precision Results accurate to 10 significant digits using NIST, CODATA, and BIPM standards.
  • 65+ Energy Units The most comprehensive collection — SI, electrical, thermal, atomic, industrial, explosives, and more.
  • Instant Results Real-time conversion as you type — no buttons to click, no waiting.
  • Works Offline All calculations run locally in your browser. Perfect for field work and labs.
  • Universal Compatibility From basic keypad phones to 4K displays — works on every device, every OS.
  • Zero Tracking No cookies, no analytics, no data collection. Your privacy is absolute.

Frequently Asked Questions

Energy is the capacity to do work or produce heat. It is a fundamental physical quantity conserved in isolated systems (First Law of Thermodynamics). Common units include:
  • Joule (J) — the SI unit, used in physics
  • Kilowatt-hour (kWh) — used in electricity billing
  • Calorie (cal/kcal) — used in nutrition and chemistry
  • BTU — used in HVAC and heating systems
  • Electronvolt (eV) — used in particle physics
  • Erg — CGS unit used in astrophysics
  • Ton of oil equivalent (TOE) — industrial energy economics
  • Ton of TNT — for explosions and large-scale events
Different fields prefer different units based on scale, tradition, and convenience.
Multiply the kWh value by 3,600,000 to get Joules. The formula is:

E(J) = E(kWh) × 3,600,000

This is because 1 kWh equals 1,000 watts × 3,600 seconds = 3,600,000 watt-seconds = 3,600,000 Joules. For example, a typical household uses about 30 kWh per day, which equals 108,000,000 Joules (108 MJ). Our converter handles this and 64 other unit conversions automatically.
This is a common source of confusion. In nutrition, the word "Calorie" (with a capital C) actually means kilocalorie (kcal), which is 1,000 small calories:
  • Small calorie (cal) = 4.184 Joules — energy to raise 1 gram of water by 1°C
  • Kilocalorie (kcal or Cal) = 4,184 Joules — energy to raise 1 kg of water by 1°C
When a food label says "200 Calories," it means 200 kilocalories or 836,800 Joules. Our converter includes both the thermochemical calorie (4.184 J) and the International Table calorie (4.1868 J) for scientific precision.
Different historical definitions exist based on the temperature range and measurement method. For BTU:
  • BTU (International Table) = 1,055.056 J — modern standard
  • BTU (thermochemical) = 1,054.350 J — used in chemistry
  • BTU (39°F) = 1,059.67 J — based on water at 39°F
  • BTU (59°F) = 1,054.80 J — US standard
  • BTU (60°F) = 1,054.68 J — used in natural gas
  • BTU (mean) = 1,055.87 J — average across range
Similarly, calories have thermochemical (4.184 J), International Table (4.1868 J), 15°C (4.1855 J), and mean (4.19002 J) variants. Our converter includes all standard variants so you can choose the exact one required for your application.
By convention, 1 ton of TNT equals exactly 4.184 gigajoules (10⁹ thermochemical calories). This unit is used to express the energy of large-scale events:
  • Ton of TNT = 4.184 × 10⁹ J — small explosions
  • Kiloton of TNT = 4.184 × 10¹² J — nuclear weapons (Hiroshima ≈ 15 kt)
  • Megaton of TNT = 4.184 × 10¹⁵ J — large nuclear weapons, asteroid impacts
  • Gigaton of TNT = 4.184 × 10¹⁸ J — mega-events like dinosaur-extinction asteroid
The Chicxulub asteroid that wiped out the dinosaurs released about 100 teratons of TNT equivalent (4.184 × 10²³ J) — energy beyond everyday comprehension.
An electronvolt (eV) is the energy gained by a single electron moving through an electric potential difference of one volt. It equals 1.602176634 × 10⁻¹⁹ Joules — an extremely small value suited for atomic and subatomic scales.

Common multiples:
  • eV — chemical bonds, visible light photons
  • keV (10³ eV) — X-rays, inner electron shells
  • MeV (10⁶ eV) — nuclear reactions, gamma rays
  • GeV (10⁹ eV) — particle physics (proton mass ≈ 0.938 GeV)
  • TeV (10¹² eV) — Large Hadron Collider energies
The LHC at CERN accelerates protons to 6.5 TeV each — energies last seen microseconds after the Big Bang.
Our converter delivers results accurate to 10 significant digits using conversion factors from official metrology institutes:
  • NIST (US National Institute of Standards and Technology)
  • CODATA (Committee on Data for Science and Technology)
  • BIPM (International Bureau of Weights and Measures)
This level of precision is suitable for physics research, engineering calculations, academic work, industrial applications, and professional publications. The elementary charge used for electronvolts is the exact CODATA 2019 value of 1.602176634 × 10⁻¹⁹ C.
Yes, the ASLI FORM Energy Converter is 100% free forever. There are no registration requirements, no usage limits, no subscription fees, and no hidden charges. We do not display advertisements and we do not collect any personal data. Our mission is to provide a premium tool that everyone can use without barriers — from students to Nobel laureates.
Yes. Once the page loads, all calculations happen locally in your browser. There is no server-side processing, no API calls, and no internet dependency for conversions. This makes the tool perfect for laboratories, field work, remote research stations, spacecraft design, and anywhere connectivity is limited. Your data never leaves your device.
The Hartree energy (Eₕ) is a natural unit of energy in atomic physics and computational chemistry, equal to 4.3597447222071 × 10⁻¹⁸ J. It is defined as twice the ionization energy of hydrogen — approximately 27.211 eV or 627.5 kcal/mol.

The Hartree is the fundamental energy unit in atomic units, used extensively in quantum chemistry calculations, density functional theory, and ab initio methods. Computational chemists routinely work with energies in Hartrees when modeling molecular systems.
Absolutely. Our converter is ideal for understanding and comparing electricity usage:
  • Convert your kWh usage to Joules to understand energy magnitude
  • Compare appliance energy consumption across different units
  • Understand the relationship between watts, kilowatts, and kilowatt-hours
  • Calculate energy costs in different currencies by converting to standard units first
A typical 100W light bulb running for 10 hours consumes exactly 1 kWh = 3,600,000 Joules = 3,412 BTU. Use the converter to explore these relationships yourself.
Power is the rate of energy transfer (energy per unit time), while energy is the total amount of work done or heat produced:
  • Power = Watts, kilowatts, horsepower (Joules per second)
  • Energy = Joules, kWh, calories, BTU (total accumulated)
Think of it like water: power is the flow rate (liters per second), while energy is the total volume (liters). A 2,000W kettle running for 3 minutes uses 2,000 × 180 = 360,000 Joules of energy. Use our Power Converter tool for power-related calculations.
Yes! Through Einstein's famous equation E = mc², energy and mass are interchangeable. While this converter focuses on energy-to-energy conversions, here are some fascinating equivalences:
  • 1 kg of mass = 8.987 × 10¹⁶ Joules (if fully converted)
  • 1 gram of matter = about 21.5 kilotons of TNT — similar to the Nagasaki bomb
  • The Sun converts about 4.26 million metric tons of mass to energy every second
For pure mass-energy conversions, you'd need a specialized relativistic calculator, but our converter handles every standard energy-to-energy conversion you'll ever need.
No. We do not collect, store, or transmit any of the values you enter. All calculations happen entirely in your browser's memory and are destroyed the moment you close the tab. We use no analytics scripts, no cookies for tracking, and no third-party services that could see your conversions. Your privacy is absolute and non-negotiable — especially important for proprietary research, military calculations, or confidential industrial work.

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