Many household appliances run on 240 watts. These include 240W ceiling fans, lamps with two 120W bulbs, small 240W heaters, 240W laptops, low-power microwave setting, 240W older plasma TVs, and 240W gaming consoles.
We are going to look at 3 things that people running 240-watt appliances need to know, namely:
- How much electricity does a 240 watts per hour use? We will calculate kWh usage.
- How much does it cost to run 240-watt appliances per hour? This depends on the electricity rate. We took the US average of $0.15/kWh to make the calculation.
- Bonus: 240-watt electricity cost calculator. Here, you can just insert your electricity rate in $/kWh, and you get 240-watt running cost per hour immediately.
Quick Example: Running a 240-watt heater uses 0.24 kWh per hour. At $0.15/kWh electricity rate, this will cost us $0.036 per hour or $0.864 per day (continuous usage).

We summarized all the calculated results in the all-encompassing chart at the end of the article (we also include electricity usage and cost per 2 hours, 4 hours, 8 hours, 12 hours, per day, per week, and per month). Let’s start with the electricity usage:
How Many kWh Does 240-Watt Appliance Use Per Hour?
Electricity usage is measured in kilowatt-hours (kWh). Here is an equation for calculating electricity usage in kWh for a 240-watt appliance:
Electricity Usage (240W) = 240 W / 1000 = 0.24 kWh/h
We see that running a 240-watt appliance uses 0.24 kWh per hour. Here is the electricity usage for various running times:
- 0.24 kWh per hour.
- 0.48 kWh per 2 hours.
- 0.96 kWh per 4 hours.
- 1.92 kWh per 8 hours.
- 2.88 kWh per 12 hours.
- 5.76 kWh per day.
- 40.32 kWh per week.
- 172.80 kWh per month.
Now that we know what is the electricity usage for 240-watt devices, we can calculate how much is the corresponding electricity price:
How Much Does It Cost To Run A 240-Watt Appliance?
We can calculate the 240-watt running cost per hour using this formula:
Cost Per Hour (240W) = (240W / 1000) ร Electricity Rate ($/kWh)
In order to calculate this, we need to know the electricity rater (cost per kWh). In the US, kWh cost ranges from low $0.10/kWh (Louisiana) to as high as $0.40/kWh (think California, Hawaii). Let’s take the US average of about $0.15/kWh to calculate the electricity cost per hour:
Cost Per Hour (240W) = (240W / 1000) ร 0.15 $/kWh = $0.036/h
We see that the average running cost for a 240-watt device is less than 4 cents per hour (3.6 US cents per hour, to be exact).
The low-end cost ($0.10/kWh) is 2.4 US cents per hour, and the high-end ($0.40/kWh) is 9.6 US cents per hour.
By the way, if you know your electricity rate, you can use this calculator to accurately calculate the 240-watt running cost per hour:
Based on this, we can calculate how much we will pay if we run a 240W appliance non-stop for longer than 1 hour. Here is the complete chart:
240-Watt Electricity Cost Chart
All these calculations are made using the US average electricity rate of $0.15/kWh, 240W appliances are running non-stop:
| 240-Watt Running Time: | Cost Of Electricity ($): |
|---|---|
| 1 Hour: | $0.036 Per Hour |
| 2 Hours: | $0.072 Per 2 Hours |
| 4 Hours: | $0.144 Per 4 Hours |
| 8 Hours: | $0.288 Per 8 Hours |
| 12 Hours: | $0.432 Per 12 Hours |
| 1 Day (24 Hours): | $0.864 Per Day |
| 1 Week: | $6.048 Per Week |
| 1 Month: | $25.92 Per Month |
As we can see, running a 240-watt appliance non-stop 24/7 at a $0.15/kWh electricity rate will cost us about $25 per month ($25.92, to be exact).
We hope that these calculations, including the chart and calculator, will help you estimate the 240-watt hourly electricity cost. If you need some help with the calculation, you are always welcome to use our comment section, explain the problem, and we can give you a hand.