Kilojoules (kJ) and kilowatt-hours (kWh) are both units used to measure energy. You’ve likely seen kWh on your electricity bill, as it’s the standard unit for measuring electrical energy consumption.
This article provides a practical guide to converting between kJ and kWh, which is valuable information for those who want to understand the amount of energy used and how much it costs.
Understanding Kilojoules
- What’s a kilojoule? A kilojoule (kJ) is how scientists measure energy.
- It’s part of the official, international system of measurement (SI).
- Think of it this way: One kilojoule is equal to one thousand joules (J).
- A “joule” is the standard unit of energy in the International System of Units (SI).
- So, kilojoules are just a way to talk about energy in different situations.
Understanding Kilowatt-Hours
A kilowatt-hour (kWh) is a unit of energy. Think of it this way: if you use 1,000 watts of power for exactly one hour, you’ve used one kilowatt-hour.
Kilowatt-hours are the standard way to measure how much electricity you use. When the utility company sends you a bill, it’s based on the number of kWh you consumed.
And just to keep things clear, a watt is a unit that measures power, or the rate at which energy is transferred.
How to convert from kJ to kWh
To convert kilojoules to kilowatt hours, you’ll use the following formula:
kWh = kJ ÷ 3,600
This is because one kWh is equal to 3,600 kJ.
Example conversion
Let’s say you want to convert 5,000 kJ to kWh. The formula looks like this:
kWh = (5,000 kJ ÷ 3,600) = 1.388889 kWh
Another quick example:
15 kJ = 0.0041666667 kWh
Kilojoule to Kilowatt-Hour Conversion Table
Sometimes, you just need a quick reference. Here’s a table to help you convert common kilojoule values to kilowatt-hours:
- 1 kJ = 0.0002777778 kWh
- 10 kJ = 0.0027777778 kWh
- 100 kJ = 0.0277777778 kWh
- 1000 kJ = 0.2777777778 kWh
If you need to convert a kilojoule value that’s not in this table, just use the formula we talked about earlier!
In Summary
Kilojoules (kJ) and kilowatt-hours (kWh) are two different ways to measure energy. There’s a specific formula to convert between them.
Knowing how to convert kJ to kWh (and vice versa) is essential for many energy-related problems and tasks, from figuring out your electricity bill to understanding the energy content of food.