Energy Converter

1. Enter the value you want to convert.
2. Choose the from unit.
3. Choose the to unit.
4. Read the result and the conversion rate.

Here is what each result means:

Energy is the capacity to do work, and it turns up everywhere: the electricity that runs your home, the calories in food, the heat from a boiler and the work done by a machine. Because these fields grew up separately, each measures energy in its own unit, which is why a value can appear in joules, calories, kilowatt-hours or BTU depending on where it comes from.

The SI unit is the joule, the energy to push with a force of one newton over one meter. It is small for everyday amounts, so larger units are common: a kilowatt-hour, the unit on your electricity bill, is 3.6 million joules, and a food kilocalorie is 4,184 joules. Converting lets you compare figures that use different units.

This converter bridges every unit through the joule. It multiplies your value by the number of joules in its unit, then divides by the number of joules in the target unit. Since each unit has a fixed value in joules, the conversions are exact and consistent.

Energy also links closely to power and cost. Power is the rate at which energy is used, so a device rated in watts consumes joules every second, and a bill in kilowatt-hours simply totals that energy over a month. Being able to move between the units makes it easy to compare the energy in a meal, a battery and a heating bill on the same footing, even when each is quoted its own way.

It converts through the joule, the SI unit of energy.

1. Your value is multiplied by its unit's value in joules.
2. That gives the energy in joules, the common base.
3. Dividing by the target unit's value in joules gives the result.

For the physics side, see the kinetic energy calculator and the power calculator.

Convert 1 kilowatt-hour to joules.

Result: 1 kWh is 3,600,000 joules, since a kilowatt is 1,000 joules per second for 3,600 seconds. The same energy is about 3,412 BTU or 860 kilocalories.

Every unit has a fixed value in joules.

The kilocalorie is the food calorie: a label that says 200 calories really means 200 kilocalories. The kilowatt-hour is the unit on electricity bills, and BTU is common for heating and air conditioning.

Each field favours a different unit.

Seeing energy in a familiar unit makes it meaningful. A 2,000 kilocalorie diet, a 10 kilowatt-hour battery and a 12,000 BTU air conditioner are all energy figures, each written in the unit its field finds most natural.

The Two Units

The ratio between the from-unit and to-unit sets the result; each has a fixed value in joules.

Which Calorie

The small calorie and the food kilocalorie differ by a factor of 1,000, so choose the right one.

The BTU Definition

Slightly different BTU definitions exist; a standard value is used here.

Food and Fitness

Convert calories to kilojoules, as many food labels show both.

Energy Bills

Compare kilowatt-hours with joules or BTU.

Science and Engineering

Move between joules and other units in calculations.

1. Confusing Calories and Kilocalories

A food calorie is really a kilocalorie, 1,000 small calories. Mixing them is off by a factor of 1,000.

2. Forgetting KWh Is Energy, Not Power

A kilowatt is power; a kilowatt-hour is energy, power multiplied by time.

3. Wrong Direction

Check which unit is the from and which is the to; swapping them inverts the result.

4. Assuming BTU Is Exact

Several BTU definitions exist that differ slightly; a standard value is used here.

5. Rounding Too Early

Convert first, then round, so small differences do not build up.

Conversions use fixed factors relative to the joule.

3,600,000 joules. A kilowatt is 1,000 joules per second, and an hour is 3,600 seconds, so a kilowatt-hour is 1,000 times 3,600.

Multiply small calories by 4.184. A food calorie is a kilocalorie, so multiply by 4,184. 500 kilocalories is 2,092,000 joules.

The joule. It is the energy used to push with a force of one newton over a distance of one meter.

No. A food calorie is a kilocalorie, 1,000 small calories. A label showing 200 calories means 200 kilocalories.

Multiply kilowatt-hours by about 3,412. One kilowatt-hour is 3,600,000 joules, and one BTU is about 1,055 joules.

A British thermal unit, the energy to raise one pound of water by one degree Fahrenheit, about 1,055 joules. It is common for heating and cooling.

No. A kilowatt is power, the rate of using energy. A kilowatt-hour is energy, a kilowatt sustained for one hour.

Different fields adopted different units over time. Food uses calories, electricity uses kilowatt-hours, and science uses joules, so converting is often needed.

No. The calculation runs in your browser and nothing you enter is stored or sent anywhere, unless you choose Save, which keeps the result only on this device.

• Joule (Wikipedia).
• Units of energy (Wikipedia).
• Kilowatt-hour (Wikipedia).