Energy Converter
The energy converter allows you to quickly and accurately convert between the most common units of energy. Whether you're working with joules, calories, kilowatt-hours, or BTUs, this tool handles the math instantly.
Energy conversions are essential in physics, nutrition, engineering, and everyday life. With different fields using different energy units — calories in food, kWh on electricity bills, joules in physics — having a reliable converter saves time and prevents errors.
How it works
Energy conversions use standardized factors. All units are converted through a base unit (Joules). For example: 1 kcal = 4,184 J, 1 kWh = 3,600,000 J, 1 BTU = 1,055.06 J. To convert between any two units, the value is first converted to J, then to the target unit.
Use cases
- Converting food energy between calories and kilojoules for nutrition tracking
- Converting electricity consumption between kWh and joules for energy analysis
- Converting thermal energy between BTU and kJ for HVAC engineering
- Converting scientific measurements between joules and electronvolts in physics research
Frequently asked questions
How many joules are in one calorie?
One thermochemical calorie equals exactly 4.184 joules, and one food Calorie (kilocalorie) equals 4,184 joules. The nutritional Calorie you see on food labels is actually a kilocalorie. To convert kcal to joules, multiply by 4,184.
How do you convert kWh to joules?
One kilowatt-hour equals 3,600,000 joules (3.6 megajoules), because it represents 1,000 watts sustained for 3,600 seconds. To convert kWh to joules, multiply by 3,600,000; to go the other way, divide joules by 3,600,000. This is the unit used on most electricity bills.
What is the difference between a calorie and a kilocalorie?
A kilocalorie (kcal) equals 1,000 small calories (cal). Food energy is measured in kilocalories, but they are often written with a capital C as Calories, so a 200 Calorie snack actually contains 200 kcal or 200,000 cal. In joules that is 836,800 J.
How many joules are in a BTU?
One British Thermal Unit (BTU) equals about 1,055.06 joules. The BTU is widely used in heating, ventilation, and air conditioning to rate energy and cooling capacity. To convert BTU to kilojoules, multiply by roughly 1.05506.
What is an electronvolt used for?
An electronvolt (eV) is a very small energy unit used in atomic and particle physics, equal to about 1.602 × 10⁻¹⁹ joules. It represents the energy gained by an electron moving through a one-volt potential difference. Because it is so tiny, it is convenient for describing energies at the atomic scale.