What is the difference between a calorie and a kilocalorie?

A kilocalorie is 1,000 calories. The confusing part is that food labels usually say "calories" but mean kilocalories, so a 200-calorie snack is really 200 kilocalories, or 200,000 small calories. This converter keeps them separate so you can be precise. One kilocalorie is about 4,184 joules.

How many joules are in a kilowatt-hour?

A kilowatt-hour is 3,600,000 joules, because one watt is one joule per second and there are 3,600 seconds in an hour. That is why kilowatt-hours, not joules, are used on electricity bills: the joule is simply too small a unit for household amounts.

How accurate are the conversions?

Each conversion uses the exact, internationally defined factor for the unit, not a rounded approximation, so the maths is precise. The result is shown to several significant figures and rounded only for display. For everyday and most professional use, the figures are exact to well beyond the precision you need.

Does this work offline and is anything sent to a server?

The conversion runs entirely in your browser, so nothing you type is sent anywhere, and once the page has loaded it keeps working with no connection. There is no sign-up and no limit on how many conversions you make.

Energy Converter

Convert energy between joules, kilojoules, calories, kilocalories, watt-hours, kilowatt-hours, BTU and foot-pounds. Type a value and see it across every unit. A free, exact energy converter that runs in your browser.

Exact, standard factors
100% free
No sign-up, no app
Instant as you type
Works offline after first load

Convert

From

0.23900574kcal

1 kJ = 0.23900574 kcal

1 kJ in every unit

Joule1,000 J

Kilojoule1 kJ

Calorie239.00574 cal

Kilocalorie0.23900574 kcal

Watt-hour0.27777778 Wh

Kilowatt-hour0.00027778 kWh

British thermal unit0.94781712 BTU

Foot-pound737.56215 ft·lb

How to use it

1
Enter a value

Type the number you want to convert. The result updates as you type, with no button to press.
2
Pick the units

Choose what you are converting from and to. Swap them with one click if you need the reverse.
3
Read or copy

See the exact result, plus a table of your value in every unit. Copy any line you need.

When it comes in handy

Food and diet

Convert between kilojoules and kilocalories, the two ways food energy is labelled in different countries.

Electricity bills

Switch between kilowatt-hours and joules to make sense of usage figures.

Heating and engineering

Convert BTU to kilowatt-hours or joules when sizing heating and cooling.

Instant, exact & 100% in your browser

The conversion runs right here in your browser using exact, standard factors. Nothing you type is sent to a server, there is no sign-up and no limit, and once the page has loaded it keeps working even with no connection.

Frequently asked questions

What is the difference between a calorie and a kilocalorie?: A kilocalorie is 1,000 calories. The confusing part is that food labels usually say "calories" but mean kilocalories, so a 200-calorie snack is really 200 kilocalories, or 200,000 small calories. This converter keeps them separate so you can be precise. One kilocalorie is about 4,184 joules.
How many joules are in a kilowatt-hour?: A kilowatt-hour is 3,600,000 joules, because one watt is one joule per second and there are 3,600 seconds in an hour. That is why kilowatt-hours, not joules, are used on electricity bills: the joule is simply too small a unit for household amounts.
How accurate are the conversions?: Each conversion uses the exact, internationally defined factor for the unit, not a rounded approximation, so the maths is precise. The result is shown to several significant figures and rounded only for display. For everyday and most professional use, the figures are exact to well beyond the precision you need.
Does this work offline and is anything sent to a server?: The conversion runs entirely in your browser, so nothing you type is sent anywhere, and once the page has loaded it keeps working with no connection. There is no sign-up and no limit on how many conversions you make.