Energy Converter

Convert energy units between Joules, Kilojoules, Calories, Kilowatt-hours, and BTU.

Secure (SSL)

Client-Side Processing

100% Free

Go to tool

Instructions

1

Enter data
Enter content, paste text or load a file from disk.
2

Click the button
The tool will immediately process your data in the browser.
3

Get the result
Copy the finished text or save the file to your device.

                                                function runTool() {

                                                  return "Result ready in 0.1s";

                                                }

Value to convert

Input unit

Enter the energy value and click "Calculate energy" to see the results in other units and comparison with real objects.

Rate this tool:

5.0 / 5 · 1 rating

Related tools

Other tools you may find useful

Meta description:Free online energy unit converter. Convert joules (J), kilojoules (kJ), calories (cal, kcal), watt-hours (Wh, kWh), electronvolts (eV), Btu, therm (US), and ft·lbf in seconds. Perfect for students, engineers, dietitians and anyone who works with energy.

Online energy unit converter - J, kJ, kcal, kWh, eV, Btu and others in one place

Energy conversion between joules, calories, kilowatt-hours or Btu does not require remembering formulas. OurEnergy Unit Converterallows you to convert energy from one unit to another in just a few seconds - transparently, accurately and without manual counting.

Run energy unit converter

online energy converter joules to calories converter kcal to kJ and J kWh to J eV to J

What can the Energy Unit Converter do?

Our tool allows you to convert energy between many of the most popular units found in physics, energy, dietetics and engineering. All you need is one input value and the converter will display the results in the selected units.

Supported energy units

Joules (J) i kilojoules (kJ)– SI units used in natural sciences and engineering;
Calories (cal) i kilocalories (kcal)– popular in dietetics and nutrition, often marked as "calories" on product labels;
Watt-hours (Wh) i kilowatt-hours (kWh)– standard in energy, electricity bills and heating technology;
Electronvolts (eV)– used in atomic, nuclear and semiconductor physics;
British Thermal Units (Btu)– popular in air conditioning and heating;
American term (therm (US))– used to settle natural gas;
Foot pounds (ft lbf)– Imperial system unit of energy/work.

Unit	Symbol	Approximate equivalence in joules
Joule	J	1 J
Calorie	inch	1 inch ≈ 4.184 J
Kilocalorie (nutritional calorie)	kcal	1 kcal = 1000 cal ≈ 4184 J
Watt hour	Wh	1 Wh = 3600 J
Kilowatt hour	kWh	1 kWh = 3,600,000 J
Electronvolt	eV	1 eV ≈ 1.602 × 10⁻¹⁹ J
Btu	Btu	1 Btu ≈ 1055 J
Therm (US)	therm	1 therm (US) ≈ 105.5 MJ
Foot-pound	ft·lbf	1 ft·lbf ≈ 1.356 J

How to use the Energy Unit Converter - step by step

Enter the energy value
In the input field, enter a known value, e.g.500, 2.5or0.0001. You don't have to use scientific notation - the tool can handle typical decimal notations.
Select the input unit
From the list, select the unit in which you enter the value: e.g.kcal, J, kWhoreV.
Select the output unit
From the second list, select the unit to which you want to convert the energy - e.g. fromcal to J, fromkJ to kcalor fromkWh to Btu.
Read the result
The converter will automatically convert the value and display the result in the selected unit. Depending on the settings, it may also show other units helpfully.