Heater wattage guide

How to Know the Heater Wattage: A Guide for Homeowners

Although you live with year-round sunshine, heating your house can be challenging. In many areas, people build houses to keep cool in summer rather than warm in winter. As a result, many people rent a heater or install an additional one in their home in order to provide comfort for their families. Before you purchase and install a new heater, you must measure how much power it uses and what that means for your home’s energy use. 

Fortunately, because heaters tend to be unique pieces of technology, many manufacturers list the wattage of their products. It makes finding the right heat settings for your home much simpler – assuming you know how to read its wattage rating. Keep reading this article for more information on what this measurement means and how you can find it on a heater before purchasing it.

How Many Watts Does a Space Heater Use?

These heaters are a better option if you spend limited time in a room and remain within the heater’s service area. When the temperature outside drops, you’ll need to keep warmth yourself and your family. Space heaters are an affordable and convenient way to do that, but you still need proper insulation in your rooms, like in the bedroom, living room, kitchen, and even in your office. Because space heaters don’t take up much space, they can be placed in rooms as necessary. 

A furnace is simply a huge electrical heater that pushes heat throughout a house using a fan heater. Many different types of space heaters are available on the market today. Some of them have a higher electricity consumption than others do. How much a given heater costs to run will depend on its size, the kind of heating element it operates, and other factors. 

In general, however, most space heaters use between 1000 and 3500 watts when running at full capacity. You should also check the energy consumption and efficiency rating to see the electricity costs it uses per hour and how many kWh it produces per day.

How Much Electricity Does a Space Heater Use?

Checking the heater or owner’s manual will tell you how much energy your electric space heater uses and asking questions from a professional will also be a big help. The amount of electricity a space heater uses varies depending on the model but typically ranges from 1,500 watts (W) to 2,000 watts (W).

Space heaters usually require 15 amps and are connected to 120-volt outlets. Its usage has the most influence on the amount of electricity used over time. This table will show if you operate your heater for eight hours per day for five months a year, it will consume:

Reference: https://news.energysage.com/how-many-watts-does-a-space-heater-use/

The amount of electricity used by different space heaters over a year is varied. Here is the chart which shows the summary of how much electricity you might use if you run your typical space heater for eight hours a day for five months:

In this piece, we will primarily discuss the difference in electricity consumed by space heaters in terms of kWh. The amount you consume each month charges you because your electricity bill is calculated in kWh.

How To Estimate Power Consumption?

Do you want to know how much electricity a particular space heater will consume? There are things that you should know. The heater or control box usually displays the electrical ratings in terms of watts (W), voltage (V), and amperage (A). You can find out how much electricity the heater will consume using this simple formula:

Watts = volts x amps x power factor

The power factor is usually a standard of 1 unit but can change. 

So space heaters labeled 120 V and 15A consume 120V x 15A x 1 = 1,800 watts or 1.8 kW.

What Is a Space Heater Power Rating?

To determine your space heater’s wattage, you must assess its power rating. Knowing this, you can get a rough idea of your heating bills. You can find out how much electricity your space heater uses by checking your heating bill. A kilowatt-hour (kWh) is a unit of measurement for electricity or heating bills. Here’s how:

  • A 1.8 kW space heater consumes a certain amount of watts over hours to determine its power.
  • Using your 1.8 kW heating devices for two hours consumes 1,800 watts × 2 hours = 3,600 watts.
  • Now divide it by 1,000 to get 3.6.
  • Divide the cost of using this heater for 2 hours by your region’s utility charges to determine how much it costs.
  • Using the heater for two hours daily equates to a monthly electricity bill of 30 times the answer.
  • Please note that this value does not include the cost of taxes and other extra charges.

Electricity charges are different in various locations, so the same space heaters charge different amounts in other areas, just like if it is in a large basement. Your electricity bill will be higher if you leave the heater on for a long time, and the output will cost you a lot of money.

Will a Larger Space Heater Consume More Electricity?

Larger spaces will consume more electricity than smaller spaces. The more prominent space heater will have to work harder to heat the larger area. The larger space heater will also have a higher wattage, which means it will use more electricity.

Keep in mind that the most significant factor in determining a space heater’s energy consumption is its size. Shape, structure, and weight are contributing factors, but the size is the most critical. Since larger heaters need more energy, they consume more electricity. The more energy a heater consumes, the more heat it generates per square foot. It results in a dramatic increase in your electricity bills.

How Do I Determine The Amount Of Energy Used By My Space Heater?

The wattage of your heater, which determines how much electricity it uses, can be found by understanding the concept. Electrical heaters are rated in watts, measuring the heating capacity and the amount of energy the heater consumes. You can find the wattage rating and energy consumption in the manufacturer’s instructions or the heater itself. The wattage advertised is usually the amount of power the heater produces, not how much power it consumes.

How To Estimate Power Consumption?

To determine the true power consumption of your space heater, you must look at the bottom or back of the device for a label. Frequently, the electrical ratings are printed on the label, showing either watts (W), voltage (V), or amperage (A).

Watts (W) = Volts (V) x Amps (A) x Power Factor.

The Power Factor is almost always set at 1, but there are exceptions to this rule. You can determine the efficiency of your space heater by using the formula listed below:

x 100 =  %

Calculate a specific numerical % (the percentage power input of the space heater in terms of heat) from the equation. For example, if your space heater is labeled as operating on 120VAC and 15A, this means that it:

120V x 15A x 1 = 1800 Watts or 1.8 kW

How Much Does It Cost To Run a 1,000-Watt Heater For 24 Hours?

The cost of heating is dependent on the heater size and location. For example, 24 hours of kilowatt-hours in San Francisco cost 20 cents per hour. To find out how much it would cost to operate a 1,000-watt heater for a day, use the following step:

1,000 x 24 x $0.20= 4,800

To convert watt-hours into kilowatt-hours, multiply by 1,000. It gives you $4.80, which tells you how much it costs to run the heater for 24 hours.

How Much Does It Cost To Run a 2,000 Watt Heater For 24 Hours?

The answer to this question depends on where you live. For instance, in San Francisco, you can estimate your running expenses using the formula given above.

2,000 x 24 x 0.20= 9,600

Running a 2,000-watt heater for 24 hours costs $9.60, given that dividing this by 1,000 yields 9.60.

How Much Does It Cost To Run An 800-Watt Heater For 24 Hours?

The cost of running an 800-watt heater for 24 hours in San Francisco, as given above, is: 

800 x 24 x 0.20=3,840

Dividing this quantity by 1,000 gives 3.84, or $3.84, as the cost of running the heater for 24 hours.

How Much Does It Cost To Run a 750-Watt Heater For 24 Hours?

The standard way to compute how much it costs to run a 750-watt heater for 24 hours is as follows: 

750 x 24 x 0.20 = 3,600 (750 x 24 x 0.20 = 3,600)

Divide by 1,000 to get 3.6 or $3.60, the cost of running a 750-watt heater for 24 hours.

How to Determine the Cost of Electricity

Once you’ve looked at your energy bill, you can see how much electricity you used and how much you charged for it. The electric charges section will show the number of kilowatt-hours, the price per kilowatt-hour, and the amount billed. It will look something like this:

90.275 * 0.139125=$12.56

You are charged $12.56 for that formula, which is 90.275-kilowatt-hours (kWh) times 13.9125 cents per kWh. Some energy providers have varying rates during the summer months depending on the time of day. Consumers’ Energy, for example, has a Peak Rate from 2 to 7 p.m. when most air conditioners are operating. The Off-Peak Rate applies the rest of the time.

In this case, your bill will look something like this.

  • On-Peak Energy 111.410* 0.143752=$16.02
  • Off-Peak Energy 402.749* 0.096781=$38.98

According to Electric Choice, an energy consultancy group, the average price of electrical energy in the US is 13.9 cents per kilowatt-hour. Hawaii and Alaska have the highest charges at over 30 cents per kilowatt-hour, while states such as Arkansas and Louisiana have the lowest at less than 10 cents per kilowatt-hour. Most states have an electricity rate from 11 to 17 cents per kilowatt-hour.


Most electric heaters consume one kilowatt (1,000 watts) per hour. The best way to determine the wattage of a heater is to check the product description. If that information is unavailable, it’s good to remember that generally, the higher the wattage, the more power the heater consumes, and therefore, more expensive it usually is per hour of run time. There are many options on the market, just like fan heaters, which are cheap, lightweight, portable, and compact.

You must research the type of unit and models that will work for your home. Reading reviews may be a big help too. And the most important thing is to choose a thermostat controlled heating device to avoid wasting energy by overheating a room.


How do you determine the cost of electricity?

You can determine the amount you will pay for electricity to run an appliance by multiplying the electricity usage (kWh) by the tariff rate (for example, 20 cents per kWh). To determine the amount of energy appliances consume (kWh), multiply the device’s wattage (kW or W) by the number of hours it uses.

Do different brands of heaters consume power differently?

The heat generated by each heater model has been specially designed to consume a specific number of power units.

Do heaters waste a lot of electricity?

Space heaters typically consume 1,500 watts of electricity and cost about 15¢ an hour to run. That may not sound like much, but leaving heaters on for long periods can be costly.