Galvin Power is reader-supported. When you buy via our links, we may earn a commission at no cost to you. Learn more

How Many Amps Does a Space Heater Use? Here’s Answer!

Written by Edwin Jones / Fact checked by Andrew Wright

how many amps does a space heater use

A heating unit is extremely useful, especially during the winter season. However, if you want to buy a new one, you should first know how many amps does a space heater use.

This is due to the fact that some heaters can reach up to 12.5 amps on average. While this number pales in comparison to your home’s total amps, it can set you back by $40 a month under frequent use.

So, let’s learn more about heater ratings below.

How Many Amps Does a Space Heater Draw?


In general, we need to know how much power an appliance can draw for circuit installation. This way, we can determine the proper size of the breaker, wire, and generator (or any backup power needed for an emergency).

For example, you may want to know how many amps a 1500 watt heater draw in order to identify which circuit it can be connected to.

In this instance, you’ll need to do some basic computation: use the formula below to calculate the total amp of the space heater.

\text{Amps (A)} = \frac{\text{Watts (W)}}{\text{Voltage (V)}}

  • For instance, if you have a 750w heater with a power rating of 120V, it may only draw 6.2 amps. Since the rating of this unit is low, you can safely use it in a 15 amp circuit.

Obviously, you’ll need to know the portable heater watts and space heater voltage (whether it needs a 120v or 220v circuit) before performing the calculation. 

Aside from the above formula, you can also determine the total current drawn using a heater amps calculator, which is easily accessible online.

However, to make things easy, I have created a chart with the average amp ratings of different space heaters, along with how many volts you may need to use them.

Space Heater Wattage 120 Volts Amp Rating  240 Volts Amp Rating
500 Watts 4.2 Amps 2.1 Amps
750 Watts 6.3 Amps 3.2 Amps
1,000 Watts 8.3 Amps 4.2 Amps
1,200 Watts 10.0 Amps 5.0 Amps
1,500 Watts 12.5 Amps 6.3 Amps
2,000 Watts 16.7 Amps 8.3 Amps

How Many Watts Do Different Space Heaters Use in a Year?

The electric heater watts table below is based on an average appliance usage of 8 hours a day and five months (or 150 days) a year. Check it out and see the estimated consumption of your unit per year.

Space Heater Wattage Hours Per Year Run Yearly kWh of Electricity
500 Watts 1,200 hours 600 kWh
750 Watts 1,200 hours 900 kWh
1,000 Watts 1,200 hours 1,200 kWh
1,200 Watts 1,200 hours 1,440 kWh
1,500 Watts 1,200 hours 1,800 kWh
2,000 Watts 1,200 hours 2,400 kWh

Space Heater Amps Use on Low

A low-rated space heater, one at 500 watts or less, will typically draw on low 4 amps of current per hour.

However, this does not always mean that adopting a low-rated unit is a smart option. Depending on the dimensions of your room, you should use the appropriate size space heater. 

Generally, 10 watts are necessary for every square foot. A 500W heater, such as the one in the example above, will only suit a 5-square-feet room, way too small for most homes.

In practice, running a low amperage or wattage heater in large rooms will result in ineffective warming, and you would not want a cold living space during winter.

How Much Does It Cost to Power a Space Heater?


In most cases, two types of space heater ratings are used in residential homes. For small rooms, we often use a low-wattage heater of around 750 watts with a 120v power source. On the higher end of the scale, we use a 1500 watt 240 volt heater.

This fact is relevant because electricity costs are mostly determined by space heater watts and the price per kWh charged by your state’s electric company.

For example, in the United States, where 1 kWh costs $0.13, a low-rating device would only cost $0.10 per hour or less, whereas a high-rating appliance would set you back $0.21 on average per hour.

Some states may charge you more or less than the said price. To illustrate, Hawaii has a rate of about $.40 per kWh, while North Dakota only has a $.10 per kWh rate.

If you multiply this cost by your normal usage time, it may add a large amount to your utility bill, right? As a result, cutting energy costs or using your unit more efficiently is advisable. In this instance, you can try the following suggestions:

  • If you have a centralized heater, you can set the thermostat at a lower temperature. This way, the heater motor will use less electricity to warm your home.
  • It is best to have adequate insulation in your home while using a heater or air conditioning equipment. Ensure that your home is free of cracks on windows and doors, the ceiling, and other sections of the house.
  • Select a space heater amperage that is appropriate for the size of your space. Checking the unit’s instructions can help, but consulting a licensed electrician can also be helpful.


What Size Battery Do You Need to Back Up a Space Heater?

To get the proper battery size, you first need to multiply the heater’s watts by your preferred working hours. After that, you can start the calculation of the battery sizing according to the heater’s total watts hours.

For example, a 1,500 watts space heater that needs to work 8 hours will need a total of 12,000 watts/hour. For that rating, you might need eight 12V 165Ah batteries to supply its power demand for 8 hours.

How Many Solar Panels Does it Take Power a Space Heater?

An average space heater with a rating of 1000 to 2000 watts typically needs four to seven 300 watts panels. It would help if you considered another calculation to determine the recommended number of panels.

First, multiply the heater wattage by the hours you prefer to use the heater. Next, divide this total watt-hour by the average sunny hours in your area.

Lastly, divide the result of the previous calculation by the panel rating you prefer to use to get the total number of panels.

How Many Space Heaters can be on a 15 Amp Circuit?

Normally, a 15 amp circuit should hold no more than 1,440 watts of load. Anything higher than this rating may cause overloads, resulting in sudden trippings of the circuit breaker.

Therefore, the safe number of heaters in a 15 amp circuit is either a single 1000 watt heater or two 500 watt units.

What Size Breaker Do I Need for a 1500-Watt Heater?

If you calculate the total amps of a 1,500 watts heater by dividing it by 120v power supply loads, you will get 12.5 amps. In this case, a 15 amp breaker will not be enough to support the current needed by a 1,500 watts heater, as breakers should only use 80% of their total capacities.

Therefore, utilizing the next breaker size, which is 20 amp, is the best thing to do. This breaker will allow you to run a heater even on its highest setting.


Knowing how many amps does a space heater use before purchasing one is a good idea. This allows you to select the appropriate device rating that will work effectively in your room. It will also serve as your reference in properly sizing its circuit breaker.

It is simple to install a circuit for a 1300 watt heater or any other rating. However, it is best to consult a professional if you are unfamiliar with electricity.

Furthermore, refer to the following article to calculate the ideal breaker’s amperage for your appliances, such as:

5/5 - (2 votes)