Unit Converters
Energy Converter
Energy — energy Converter converts between energy units — joules, calories, kilowatt-hours and BTU — through a joule base. This page runs that same calculation on your numbers, in your browser: no signup, no uploads, nothing stored.
Use Energy Converter to convert an energy measurement between units such as joules, calories, kilowatt-hours and BTU: give it your value plus the source and target units, press Calculate, and read off the converted energy in the unit you choose — all worked out on your device.
Calorie uses the thermochemical definition (4.184 J); BTU uses the International Table convention. The electronvolt follows the SI elementary-charge definition.
About this calculator
Energy Converter converts between energy units — joules, calories, kilowatt-hours and BTU — through a joule base. It matters whenever the same quantity is expressed in two systems and a wrong factor silently breaks the answer. Here is the calculation on real numbers: Convert 1 kWh to joules: 1 × 3,600,000 = 3.6 × 10 6 J (1 kWh = 3.6 MJ). For your own figures, use the calculator above — same method, your inputs, computed on-device.
How to use
- Enter the energy value.
- Choose the From energy unit.
- Choose the To energy unit.
- Press Calculate to see the converted energy.
Why use Energy Converter
Fast
Calculations run in your browser. No round trip to a server.
Private
Your inputs never leave your device. Nothing is uploaded.
Free
No signup, no paywall, no ads-in-results, no watermarks.
Accurate
Uses standard conversion factors where applicable. Check critical engineering or measurement results before relying on them.
Mobile-ready
Optimised for phones, tablets, and desktops alike.
Transparent
Honest disclaimers wherever browser limits or regional rules apply.
Common uses
Use it for engineering and physics work
Energy in lab and technical tasks
Energy in trade and workshop work
Use it for science and research
Use it when reading a spec sheet
Use it when a manual uses different units
Technical notes
Energy Converter converts between energy units — joules, calories, kilowatt-hours and BTU — through a joule base.
Conversions use standard reference factors; for trade or engineering tolerances keep more decimal places than the display shows.
Nothing you type is uploaded — the calculation happens entirely on your device.
FAQ
Which energy units are supported?
Joules, kilojoules, calories, kilocalories, watt-hours, kilowatt-hours, and BTU.
How many joules are in a kilojoule?
1000, so 1 J equals 0.001 kJ.
Is a food Calorie the same as a calorie?
A food Calorie is a kilocalorie (kcal), which is 1000 small calories.
Does the Energy Converter send my data to a server?
No. The Energy Converter runs entirely in your browser, so nothing you enter is uploaded, stored, or shared.
Worked example
Convert 1 kWh to joules: 1 × 3,600,000 = 3.6 × 106 J (1 kWh = 3.6 MJ).