Heat Pump vs. Space Heater: Which Costs Less to Run?

Heat Pump vs. Space Heater: The Quick Answer

A heat pump usually costs less to operate than an electric space heater when both provide the same amount of heat.

A typical portable space heater uses electric resistance heating. It converts electricity directly into heat, so a 1,500-watt heater consumes up to 1.5 kWh for every hour of full-power operation.

A heat pump works differently. Instead of producing all its heat from electricity, it transfers heat from the outdoor air into the home. According to ENERGY STAR, switching from electric resistance heating to an air-source heat pump can reduce heating electricity use.

However, the least expensive option for a particular household also depends on how much space is being heated. A space heater may cost less overall if it heats only one occupied room while a central heat pump would heat the entire house.

Space Heater Electricity Cost

Most full-size portable electric space heaters sold in the United States have a maximum power setting of approximately 1,500 watts, or 1.5 kilowatts.

The operating-cost formula is:

Electricity cost = power in kW × hours used × electricity rate

At an electricity rate of $0.20 per kWh, a 1,500-watt space heater costs:

1.5 kW × $0.20 per kWh = $0.30 per hour

Four hours per day

At full power, the heater would consume:

1.5 kW × 4 hours = 6 kWh per day

Over a 30-day month:

6 kWh × 30 days = 180 kWh per month

Estimated cost:

180 kWh × $0.20 = $36 per month

Eight hours per day

At full power, the heater would consume:

1.5 kW × 8 hours = 12 kWh per day

Over a 30-day month:

12 kWh × 30 days = 360 kWh per month

Estimated cost:

360 kWh × $0.20 = $72 per month

Twelve hours per day

At full power, the heater would consume:

1.5 kW × 12 hours = 18 kWh per day

Over a 30-day month:

18 kWh × 30 days = 540 kWh per month

Estimated cost:

540 kWh × $0.20 = $108 per month

These examples assume continuous operation at the heater’s maximum setting. A thermostatically controlled heater may cycle off after the room reaches the selected temperature, reducing actual consumption.

Use the WattBasis Electricity Cost Calculator to calculate the cost with your heater’s wattage, daily runtime, and local electricity price.

How Much Electricity Does a Heat Pump Use?

Heat pump electricity use varies significantly according to:

• System size and heating capacity

• Outdoor temperature

• Indoor thermostat setting

• Home insulation and air leakage

• Equipment efficiency

• Installation quality

• Duct condition

• Defrost cycles

• Use of backup resistance heat

A heat pump’s efficiency can be described using its coefficient of performance, commonly abbreviated as COP.

A COP of 3 means the system provides approximately three units of heat for every unit of electricity consumed under the measured operating conditions.

Unlike a resistance heater, a heat pump’s COP is not constant. It can change as the outdoor temperature and heating demand change.

Equal-Heat Cost Comparison

Comparing only the wattage printed on each appliance can be misleading. The better comparison is the electricity required to deliver the same amount of heat.

Suppose a 1,500-watt space heater runs at full output for eight hours per day. It uses:

1.5 kW × 8 hours × 30 days = 360 kWh per month

At $0.20 per kWh, that equals:

360 kWh × $0.20 = $72 per month

Now assume a heat pump must provide the same amount of heat.

Heat pump operating at a COP of 2

The approximate electrical input would be:

1.5 kW ÷ 2 = 0.75 kW

Monthly electricity use:

0.75 kW × 8 hours × 30 days = 180 kWh

Estimated monthly cost:

180 kWh × $0.20 = $36 per month

Heat pump operating at a COP of 3

The approximate electrical input would be:

1.5 kW ÷ 3 = 0.5 kW

Monthly electricity use:

0.5 kW × 8 hours × 30 days = 120 kWh

Estimated monthly cost:

120 kWh × $0.20 = $24 per month

Heat pump operating at a COP of 4

The approximate electrical input would be:

1.5 kW ÷ 4 = 0.375 kW

Monthly electricity use:

0.375 kW × 8 hours × 30 days = 90 kWh

Estimated monthly cost:

90 kWh × $0.20 = $18 per month

In this simplified equal-heat example, the estimated monthly costs are:

• Space heater: $72

• Heat pump at COP 2: $36

• Heat pump at COP 3: $24

• Heat pump at COP 4: $18

These are illustrative calculations, not guaranteed operating costs. Actual heat pump performance depends on the equipment, outdoor conditions, installation, and heating load.

Why Heat Pumps Can Cost Less

An electric resistance heater creates heat by passing electricity through a heating element.

A heat pump uses electricity to operate a compressor and fans while transferring existing heat from one location to another. This allows it to deliver more usable heat than would be produced by converting the same amount of electricity directly through resistance heating.

The U.S. Department of Energy reports that modern air-source heat pumps can substantially reduce electricity consumption compared with electric furnaces and baseboard heaters.

That efficiency advantage can produce meaningful savings when comparing systems that heat the same area to the same temperature.

When a Space Heater May Cost Less Overall

A heat pump is normally more efficient per unit of heat, but efficiency is not the only factor affecting the electric bill.

A space heater may have a lower total operating cost when it is used for limited zone heating.

For example, imagine someone working in one bedroom while the rest of the house is unoccupied. Running a 1,500-watt heater in that room may consume less total electricity than operating a large central system that heats several unused rooms.

A space heater may make sense for:

• Heating one occupied room for a short period

• Supplementing heat in a cold home office

• Providing temporary heat during a heating-system repair

• Heating a small area that is difficult to reach with the main system

• Occasional use in a mild climate

This comparison changes if the heat pump is a ductless mini-split serving only that same room. In that case, the mini-split will usually have a strong operating-cost advantage because both systems heat a similar area, but the heat pump uses electricity more efficiently.

Central Heat Pump vs. One-Room Space Heater

A central heat pump and a portable space heater do not always perform the same job.

The central system may heat:

• Multiple bedrooms

• Bathrooms

• Hallways

• The kitchen

• The living room

• Other conditioned spaces

The portable heater may heat only one room.

Therefore, a central heat pump could consume more electricity in total even though it uses less electricity per unit of heat delivered.

For a fair comparison, consider:

• The number of rooms being heated

• The temperature maintained in each room

• The number of operating hours

• Heat loss through windows, doors, and walls

• Whether unused rooms can be closed or zoned

• The actual power consumption of each system

Ductless Mini-Split vs. Space Heater

A ductless mini-split heat pump is a more direct alternative to a space heater because it can heat a single room or defined zone.

A properly sized mini-split can offer:

• Lower electricity use for the same heating output

• Automatic temperature control

• Heating and air conditioning from one system

• More even room temperatures

• No energy loss through central ductwork

• Quieter operation than many portable fan heaters

The main disadvantage is the initial purchase and installation cost. A portable heater can be plugged into an appropriate wall outlet, while a mini-split normally requires professional installation.

For a room that needs heating only a few days per year, the operating savings may not justify installing a dedicated heat pump. For a frequently occupied room that needs regular heating and cooling, the long-term calculation may favor the mini-split.

How Cold Weather Changes the Comparison

Heat pump performance can decrease as outdoor temperatures fall.

When it becomes colder outside:

• The home loses heat more rapidly

• The heat pump may run longer

• The system’s heating capacity may decrease

• The coefficient of performance may fall

• Defrost cycles may temporarily increase electricity use

• Backup electric resistance heat may activate

Modern cold-climate heat pumps are designed to operate at lower outdoor temperatures than many older systems. Nevertheless, performance differs by model.

Check the manufacturer’s heating-capacity and efficiency data at the winter design temperature for your location. Do not assume that a system will maintain the same COP under every weather condition.

Watch for Backup Electric Heat

Some central heat pumps include electric resistance heating elements for supplemental or emergency heat.

These heating strips can require much more electricity than the heat pump compressor alone. If they operate frequently, the system’s cost advantage may shrink.

Backup heat may activate because of:

• Extremely cold outdoor temperatures

• A large thermostat increase

• Incorrect thermostat settings

• Insufficient heat pump capacity

• Equipment problems

• A defrost cycle

• Improper system configuration

Avoid making unnecessarily large thermostat changes unless the system has controls designed to manage them efficiently. If backup heat appears to run continuously, consider having the system inspected.

How to Estimate Your Own Heating Cost

Start by finding your electricity rate. If you are unsure which number to use, read the WattBasis guide on how to find your electricity rate.

Space heater calculation

Use:

Monthly cost = heater kW × daily hours × 30 × electricity rate

For a 1,500-watt heater:

Heater power = 1.5 kW

Example:

1.5 kW × 5 hours × 30 × $0.20 = $45 per month

Heat pump calculation

The most accurate method is to measure the system’s actual electricity consumption over a representative period.

If measured consumption is unavailable, use manufacturer performance data that matches the approximate outdoor temperature and heating demand.

A simplified equal-output estimate is:

Heat pump electrical input = required heating output ÷ COP

Then calculate:

Monthly cost = electrical input in kW × daily runtime × 30 × electricity rate

A heat pump does not necessarily operate at one fixed input level. Variable-speed systems can adjust output, so this simplified formula should be treated as an estimate.

Upfront Cost vs. Operating Cost

A portable space heater has a relatively low upfront cost and requires no permanent installation.

A heat pump generally has a higher initial cost because it may require:

• HVAC equipment

• Electrical work

• Refrigerant lines

• Indoor and outdoor units

• Duct modifications

• Professional installation

• Permits or inspections

The simplest payback calculation is:

Simple payback period = additional upfront cost ÷ annual operating-cost savings

For example, if one option costs $2,400 more initially but saves an estimated $600 per year, the simple payback would be:

$2,400 ÷ $600 = 4 years

This is only an illustrative formula. Obtain real installation estimates, equipment specifications, electricity rates, and expected operating hours before making a purchase decision.

Also check for current utility rebates or other incentives in your location.

Ways to Reduce Heating Electricity Use

Regardless of which heating method you use, several improvements can reduce consumption.

Seal air leaks

Cold air entering through doors, windows, attic openings, and wall penetrations increases the amount of heat the system must provide.

Improve insulation

Insulation slows heat transfer and can reduce how frequently the heating equipment needs to operate.

Heat occupied areas

Avoid maintaining high temperatures in unused rooms when the heating system and home layout allow safe zoning.

Use reasonable thermostat settings

Every additional degree can increase the heating demand, particularly during cold weather.

Maintain heat pump equipment

Dirty filters, blocked outdoor units, incorrect refrigerant charge, and duct leakage can reduce performance.

Measure actual energy use

A compatible electricity monitor can provide a more accurate cost estimate than relying only on rated wattage.

You can enter the measured kWh into the WattBasis Electricity Cost Calculator.

Space Heater Safety

Portable heaters require careful placement and operation.

The U.S. Consumer Product Safety Commission provides fire-safety guidance for home heating equipment.

Follow the heater manufacturer’s instructions and basic precautions:

• Keep the heater on a stable, level surface

• Maintain at least three feet of clearance from curtains, bedding, furniture, paper, and other combustible materials

• Plug the heater directly into an appropriate wall outlet

• Do not use an extension cord or power strip unless the manufacturer explicitly permits it

• Inspect the cord and plug for damage or overheating

• Keep children and pets away from the heater

• Turn the heater off when leaving the room

• Do not leave it operating unattended or while sleeping

• Keep working smoke alarms in the home

• Stop using the heater if the plug, outlet, or cord becomes unusually hot

A heat pump avoids placing a portable heating element in the occupied space, but it must still be correctly installed and maintained.

Which Option Is Better?

Choose a heat pump when:

• You need regular heating for a large part of the winter

• You want both heating and air conditioning

• You are replacing electric resistance heating

• You want lower electricity use for the same heating output

• You plan to remain in the home long enough to benefit from operating savings

• A properly sized system can serve the required rooms

Choose a space heater when:

• You need temporary or occasional heating

• You want to heat one small occupied room

• Installing permanent HVAC equipment is not practical

• The main heating system does not need to heat the rest of the house

• You can operate the heater safely

Frequently Asked Questions

Is a heat pump cheaper to run than a 1,500-watt heater?

Usually, yes, when both systems provide the same amount of heat to the same space. A heat pump can transfer multiple units of heat for each unit of electricity consumed, while the resistance heater converts electricity directly into heat.

How much does a 1,500-watt space heater cost per hour?

At $0.20 per kWh, it costs approximately:

1.5 kW × $0.20 = $0.30 per hour

At $0.15 per kWh, it costs approximately $0.225 per hour.

At $0.30 per kWh, it costs approximately $0.45 per hour.

Can one space heater reduce my heating bill?

Possibly. It may reduce total consumption if it allows you to lower the central thermostat and heat only one occupied room.

It may increase the bill if it is added without reducing the main system’s workload.

Does a space heater use 1,500 watts continuously?

Not always. A heater may use approximately 1,500 watts while its heating element is active, but a thermostat can cycle the element on and off. Actual electricity use depends on room temperature, insulation, thermostat setting, and operating time.

Do heat pumps work in cold climates?

Many modern heat pumps can operate in cold conditions, but heating capacity and efficiency vary by model and outdoor temperature. Review certified performance data and select equipment designed for the local climate.

Is a mini-split cheaper than a space heater?

For equivalent room heating, a ductless mini-split will generally use less electricity. Whether it saves money overall depends on installation cost, annual runtime, local electricity prices, and how long the system remains in service.

Bottom Line

A heat pump is normally the less expensive option to operate when it and a space heater deliver the same amount of heat.

In the example used in this guide, a 1,500-watt space heater running eight hours per day costs approximately $72 per month at $0.20 per kWh. A heat pump delivering an equivalent amount of heat at a COP of 3 would cost approximately $24 per month.

However, a portable space heater can still be economical for short-term heating in one occupied room, especially when the alternative is heating an entire home.

Compare the same heated area, use your actual electricity rate, consider local winter temperatures, and account for both installation and operating costs before deciding.