Do Space Heaters Use a Lot of Electricity? Cost and Wattage Explained
A space heater warms the room quite well, but the amount of energy it consumes depends on its internal mechanisms, thermostat, and heating technology.
You may want to keep your heater going during power cuts or even when off-grid, and an EcoFlow DELTA Pro 3 backup generator is all you need. So, do space heaters use a lot of electricity?
The short answer is yes, they do consume a lot of power, but how much your power bill will vary depends on your setup.
How Much Electricity Does a Space Heater Use?
Most space heaters use between 750 and 1,500 watts of electricity, which is the maximum allowed in standard household outlets. Understanding the electricity electric space heaters use starts with wattage, but things change when you add room size, heating elements, and duty cycles.
Baseline Wattage
Most standard household appliances draw between 750W at low power and 1,500W at high power. That maximum draw is not random. According to the National Electrical Code (NEC), 1,500W is the safest continuous load for standard household appliances.
If you use a 1,500W heater for one hour at maximum, this means that it consumes 1.5kWh of electricity, which, at an average electricity rate of about $0.16 per kWh, comes to roughly $0.44 per hour.
Electric Heaters and How They Cycle
Simple electric resistance heaters (such as fan-forced wire heaters or ceramic models) convert nearly 100% of their electrical draw into heat. Because their output is so closely matched to their draw, they rely on thermostats within the units.
Once the ceramic heater has warmed a room to your preferred temperature, the thermostat cuts power to the heating element and turns it on and off throughout the day.
Does Size Change the Wattage?
No, the physical size of most residential space heaters does not determine their electricity usage. So do small space heaters use a lot of electricity? The answer is yes. Compact personal heaters may use as much as 1,500 watts, just like larger units, because 1,500 W is the standard safe limit for a standard 120V 15-amp branch circuit recommended by Intertek/ETL safety testing standards.
Physical size dictates the area the space heater heats, not the overall wattage it draws from the wall circuit.
Do Space Heaters Use a Lot of Electricity Compared to Central Heat?
Yes, central HVAC systems use far more electricity than space heaters as a whole-home heating solution, as a furnace or heat pump will often use 3,500W to 5,000W or more when burning natural gas or connected to a forced hot water heating system.
Heating an empty guest room or office heated by central air conditioning wastes a huge amount of thermal energy.
Their solution is simple:
Zone heating: Lowering your central heating thermostat to 62 degrees and using a space heater to warm your active living area to 68 degrees will cut your overall household heating costs.
Whole-house heating: Leaving your central heating thermostat at 70 degrees while using multiple space heaters to supplement your heating in other areas will cause your electricity bills to skyrocket.
Radiator Dynamics: Oil-filled heaters
Oil filled radiator space heaters usually operate in the same 700W to 1,500W power range but use a unique heating medium that allows them to store far more energy than a standard convection space heater. Instead of using an open heating coil to directly heat the air, oil filled radiators use diathermic oil contained within the metal fins to indirectly heat the air in a room.
While oil filled radiators do take longer to reach the desired temperature because the oil itself must be heated, they also retain the heat far longer after being turned off due to the high surface area of the metal fins.
Oil filled space heaters are far more energy efficient as a result, since they reduce the amount of time that the internal heating element must be actively drawing power from the wall circuit.
Calculating Your Own Space Heater's Runtime and Cost
Since room temperature and electric rate can differ, a simple calculation is necessary to determine the costs. Using an average will not give an accurate estimate.
To calculate operating cost:
Calculate kWh: Multiply the heater’s wattage by the hours used, then divide by 1,000.
kWh = Watts x Hours / 1000
Calculate Cost: Multiply total kWh by your local electric rate per kWh
Cost= kWh x Local Rate per kWh
Example: Running a 1,500W unit for 8 hours at $0.16/kWh:
1500 x 8 / 1000 = 12 kWh
12kWh x $0.16 = $1.92 per day
Calculating Off-grid Run time
Calculating battery backup capacity is equivalent to multiplying the total Watt-hours (Wh) of the power station by the appliance's wattage rating. Learn more about battery loads in our guide on Watts Law vs Ohms Law Formulas.
Running Any Type of Space Heater Off Grid
To run your space heater off-grid, you need a portable power station with an output from the inverter greater than the wattage of your space heater and plenty of battery capacity to handle the high resistive loads. High resistive loads drain your battery quickly, so make sure your battery capacity can handle the power demands for your running time.
To remain warm during an emergency without electricity, you will need a good battery system:
Short Outages and Supplemental Heat
The EcoFlow DELTA 3 Plus Portable Power Station features a 1,024Wh battery capacity and 1,800W of continuous power. It can start a 1,500W heater and give it about 45–60 minutes of continuous high heat or several hours with a 500W personal heater.
Extended Outages and Overnight Use
The EcoFlow DELTA Pro 3 Portable Power Station has a 4096Wh capacity (up to 12kWh) and a 4000W output inverter. That means it can easily power a 1500W space heater for almost three hours or run oil filled radiators on a low setting continuously throughout the night.
To learn more about the battery capacity you will need for your space heater, find out whether a portable power station can run a heater.
Conclusion
Space heaters can use a significant amount of electricity, especially when running at higher wattages for several hours. However, their actual energy consumption depends on the heater’s wattage, how long you use it, and the heat setting.
And if you need to run your space heaters off-grid, EcoFlow DELTA 3 Plus and EcoFlow DELTA Pro 3 are no doubt good choices.
FAQs
How much does it cost to run a space heater for 1 hour?
The average cost for 1 hour of use is based on a national average of $0.16/kWh; running a standard 1,500W heater at full power costs roughly $0.24 per hour. For example, a 750W space heater on a low setting would cost about $0.12 per hour.
Is it cheaper to turn the heat up or use a space heater?
A space heater can be cheaper to use if you have a zone heating strategy instead of turning up your central heating and thermostat. However, space heaters used in more than one room are much more expensive than central heating.
Which type of heater is the cheapest to run?
Oil-filled radiators tend to be the most economical to run, as they retain heat for the longest amount of time and do not cycle on and off as often. Micathermic panel heaters are also good options, as they produce the fastest, most intense heat.
Do space heaters use more power than AC?
It depends. A 1,500W space heater will use 1.5kWh per hour on the max setting, while an air conditioner will use anywhere between 3,000W and 5,000W for the same amount of time.
How many watts does a space heater use?
Most standard space heaters range between 750W on the lowest setting and 1,500W on the highest. Smaller personal heaters range between 200W and 500W.
Do space heaters use a lot of electricity?
It depends on their wattage range, how long they are being used, and how they are being used. Calculate how much energy you are using with our kWh calculator tool, and pair your heater or space heater with a battery backup system for cold winter nights without the high electric bill. For more strategies, see our in-depth guide on space heater energy consumption.
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