Energy
The kWh on your electricity bill and the kcal on a food label are the same quantity – energy. 1 kWh = 3 600 000 J, 1 kcal = 4 184 J. Edit, print and share.
The energy table links the kilowatt-hours on your electricity bill to the kilocalories on a food label – both measure energy, just in different units. 1 kWh = 3 600 000 J exactly and 1 kcal = 4 184 J exactly. Made for the classroom and home.
| 1 kWh | = | 3 600 000 J |
|---|---|---|
| 1 kWh | = | 3 600 kJ |
| 1 kWh | = | 3.6 MJ |
| 1 MJ | = | 1 000 kJ |
| 1 kJ | = | 1 000 J |
| 1 MJ | = | 1 000 000 J |
| 1 kcal | = | 4 184 J |
| 1 kcal | = | 4.184 kJ |
| 1 kcal | = | 1 000 cal |
| 1 cal | = | 4.184 J |
How the table works
Every row is a unit conversion: a quantity and unit on the left, the same quantity expressed in another unit on the right. The table is live – drag the handle to reorder, click a row to change the quantity or units, remove rows with the cross and add your own at the bottom.
Everything you change lands in the page address. Copy the link and others open exactly your table – handy when the whole class needs the same sheet. Your changes are also kept in your browser until you reset them, but only there: to share or keep them permanently, the link is what counts.
Print puts the table on a single portrait A4 and Download PDF gives you the same sheet as a file. Print practice sheet gives the table with empty answer cells and name/date lines – the normal printout is the answer key.
The electricity bill and the food label measure the same thing
kWh on the electricity bill and kcal on a food label are both energy – just different units for the same quantity, the way metres and feet both measure length. 1 kWh = 3 600 000 J exactly, and 1 kcal = 4 184 J exactly.
Common mistake: when people talk about “calories” in food they almost always mean kilocalories (kcal), not the much smaller calorie (cal). The difference is a factor of 1 000.
Roughly how much energy?
- A banana has roughly 100 kcal.
- A hot shower uses roughly 1.5 kWh.
- A minute in the microwave takes roughly 48 kJ.
- A marathon runner burns roughly 2 500 kcal.
Frequently asked questions
How many joules are there in a kWh?
1 kWh = 3 600 000 J.
How do I convert kcal to kJ?
Multiply by 4.184. 1 kcal = 4.184 kJ.
What’s the difference between kcal and cal?
A factor of 1 000 – 1 kcal = 1 000 cal. The “calories” on a food label are in practice kilocalories.
More tables: Power · Data storage · Prefix ladder · Energy converter