Watt-hour to Kilojoule Converter
Enter the value that you want to convert watt-hour (W/h) to kilojoule (kJ) or kilojoule to watt-hour.Also written as W/H to KJ conversion.
1 watt-hour = 3.6000000 kilojoule
Formula: kilojoule = watt-hour value × 3.6000000
W/H to KJ — watt-hour to kilojoule
10 watt-hour = 36.00000 kilojoule
Popular Energy Converters:
Why Convert Watt-hour to Kilojoule?
What is Watt-hour?
Watt-hour (W/h) is a unit of energy measurement. 1 watt-hour is equal to 3.6000000 kilojoule.
About the Kilojoule
Kilojoule (kJ) is a unit of energy measurement. 1 kilojoule is equal to 0.2777778 watt-hour.
Energy Units in Different Fields
Energy measurement units reflect their historical origins across different industries. Electrical engineers use kilowatt-hours, nutritionists use calories, physicists use joules, heating engineers use BTUs, and the petroleum industry uses barrels of oil equivalent. Converting between these units is essential for energy auditing, comparing fuel sources, sizing HVAC systems, and understanding electricity bills relative to gas consumption.
watt-hour to kilojoule metric conversion table
| 0.01 W/h | = | 0.03600 kJ |
| 0.1 W/h | = | 0.36000 kJ |
| 1 W/h | = | 3.60000 kJ |
| 2 W/h | = | 7.20000 kJ |
| 3 W/h | = | 10.80000 kJ |
| 4 W/h | = | 14.40000 kJ |
| 5 W/h | = | 18.00000 kJ |
| 6 W/h | = | 21.60000 kJ |
| 7 W/h | = | 25.20000 kJ |
| 8 W/h | = | 28.80000 kJ |
| 9 W/h | = | 32.40000 kJ |
| 10 W/h | = | 36.00000 kJ |
| 11 W/h | = | 39.60000 kJ |
| 12 W/h | = | 43.20000 kJ |
| 13 W/h | = | 46.80000 kJ |
| 14 W/h | = | 50.40000 kJ |
| 15 W/h | = | 54.00000 kJ |
| 16 W/h | = | 57.60000 kJ |
| 17 W/h | = | 61.20000 kJ |
| 18 W/h | = | 64.80000 kJ |
| 19 W/h | = | 68.40000 kJ |
| 20 W/h | = | 72.00000 kJ |
| 30 W/h | = | 108.00000 kJ |
| 40 W/h | = | 144.00000 kJ |
| 50 W/h | = | 180.00000 kJ |
| 60 W/h | = | 216.00000 kJ |
| 70 W/h | = | 252.00000 kJ |
| 80 W/h | = | 288.00000 kJ |
| 90 W/h | = | 324.00000 kJ |
| 100 W/h | = | 360.00000 kJ |
| 200 W/h | = | 720.00000 kJ |
| 300 W/h | = | 1080.00000 kJ |
| 400 W/h | = | 1440.00000 kJ |
| 500 W/h | = | 1800.00000 kJ |
| 600 W/h | = | 2160.00000 kJ |
| 700 W/h | = | 2520.00000 kJ |
| 800 W/h | = | 2880.00000 kJ |
| 900 W/h | = | 3240.00000 kJ |
| 1000 W/h | = | 3600.00000 kJ |
How to Convert W/H to KJ (Watt-hour to Kilojoule)?
We can convert watt-hour to kilojoule by using an example.
Example:
Convert 20 Watt-hour to Kilojoule?
We know 1 Watt-hour = 3.6000000 kilojoule; 1 Kilojoule = 0.2777778 watt-hour.
20 watt-hour = ___kJ
20 × 3.6000000 = 72.00000 kJ (we know 1 watt-hour = 3.6000000 kilojoule)
Answer:
20 watt-hour = 72.00000 kilojoule
How to Convert Watt-Hours to Kilojoules (Step-by-Step)
Converting Wh to kJ is common when comparing battery specifications with engineering energy requirements. The conversion factor is 1 Wh = 3.6 kJ. This is the same relationship as kWh-to-MJ, just scaled down by a factor of 1000.
- Identify the energy value in watt-hours.
- Multiply by 3.6 to convert to kilojoules.
- This follows from: 1 Wh = 3600 J = 3.6 kJ.
- The result is in a convenient range for battery and small device analysis.
Common Wh to kJ Conversions
Reference values for converting battery and device energy from watt-hours to kilojoules.
| Watt-hour | Kilojoule |
|---|---|
| 1 Wh | 3.6 kJ |
| 10 Wh | 36 kJ |
| 20 Wh | 72 kJ |
| 50 Wh | 180 kJ |
| 100 Wh | 360 kJ |
| 250 Wh | 900 kJ |
| 1000 Wh (1 kWh) | 3,600 kJ (3.6 MJ) |
Solved Examples: Wh to kJ
Question 1: A laptop battery is rated at 56 Wh. Express the stored energy in kJ.
Solution:
Start with 56 Wh.
Multiply by 3.6: 56 × 3.6 = 201.6 kJ.
Answer: 56 Wh = 201.6 kJ
Question 2: An e-bike battery holds 500 Wh. How many kJ is that?
Solution:
Start with 500 Wh.
Multiply by 3.6: 500 × 3.6 = 1,800 kJ.
This equals 1.8 MJ.
Answer: 500 Wh = 1,800 kJ = 1.8 MJ
Question 3: A wireless speaker battery holds 22.2 Wh. Convert to kJ.
Solution:
Start with 22.2 Wh.
Multiply by 3.6: 22.2 × 3.6 = 79.92 kJ.
Answer: 22.2 Wh = 79.9 kJ
Practice: Wh to kJ
Try solving these on your own to test your understanding:
- Convert 15 Wh to kJ. (Answer: 54 kJ)
- A tablet has a 28 Wh battery. Express in kJ. (Answer: 100.8 kJ)
- Convert 75 Wh to kJ. (Answer: 270 kJ)
- A camera battery holds 14 Wh. Convert to kJ. (Answer: 50.4 kJ)
- Convert 300 Wh (portable power station) to kJ. (Answer: 1,080 kJ)
Comparing Devices by Energy Storage in kJ
Using kJ as a common unit allows comparison across devices: Wireless earbuds: 1–2 Wh = 3.6–7.2 kJ. Smartphone: 15–20 Wh = 54–72 kJ. Tablet: 25–40 Wh = 90–144 kJ. Laptop: 50–100 Wh = 180–360 kJ. Electric scooter: 200–500 Wh = 720–1,800 kJ. E-bike: 400–750 Wh = 1,440–2,700 kJ. This progressive scale shows how energy capacity increases with device size.
Energy Density: Wh/kg and kJ/kg for Batteries
Battery technology is often compared by energy density. Lithium-ion: 150–260 Wh/kg = 540–936 kJ/kg. Lead-acid: 30–50 Wh/kg = 108–180 kJ/kg. Lithium iron phosphate (LFP): 90–160 Wh/kg = 324–576 kJ/kg. Solid-state (future): 400+ Wh/kg = 1,440+ kJ/kg. These kJ/kg values can be directly compared with chemical fuels (gasoline: 46,000 kJ/kg), showing why batteries are still much heavier than fuel tanks for equivalent energy.
Key Takeaways
- Multiply Wh by 3.6 to get kJ (exact conversion).
- 1 Wh = 3.6 kJ; 1 kWh = 3,600 kJ = 3.6 MJ.
- Smartphone (~18 Wh) ≈ 65 kJ; laptop (~70 Wh) ≈ 252 kJ.
- Airline carry-on limit (100 Wh) = 360 kJ.
- kJ is more readable than raw joules for battery comparisons.
- Battery energy density: Li-ion ≈ 150–260 Wh/kg = 540–936 kJ/kg.
Watt-hour to Kilojoule Conversion Formula
kilojoule = watt-hour × 3.6000000
1 watt-hour = 3.6000000 kilojoule
1 kilojoule = 0.2777778 watt-hour
Reverse: watt-hour = kilojoule × 0.2777778
Frequently Asked Questions
How many kilojoule are in 1 watt-hour?
There are 3.6000000 kilojoule in 1 watt-hour. To convert watt-hour to kilojoule, multiply the value by 3.6000000.
How do I convert watt-hour to kilojoule?
Multiply your watt-hour value by 3.6000000 to get the equivalent in kilojoule. For example, 5 watt-hour = 5 × 3.6000000 = 18.00000 kilojoule.
How do I convert kilojoule to watt-hour?
Multiply your kilojoule value by 0.2777778 to get the equivalent in watt-hour. Alternatively, divide by 3.6000000.
What is 10 watt-hour in kilojoule?
10 watt-hour is equal to 36.00000 kilojoule.
What is 100 watt-hour in kilojoule?
100 watt-hour is equal to 360.00000 kilojoule.