Heat pumps rank among the most energy-intensive appliances in your household. But precisely how much electricity does a heat pump use?
Well, there are a few electrical units that measure each aspect of electricity, such as:
- Amps, which measure Electrical Current.
- Volts, which measure Electrical Potential.
- and Watts, which measure Electrical Power.
Understanding these aspects of electricity usage in your heat pump can prove valuable for different purposes.
However, what you ultimately pay for each month is your Electrical Energy usage, measured in “kiloWatt-hours”, or “kWh” for short.
In this article, I’ll first explore the Energy Use of heat pumps in kWh, offering some rough estimates of their kWh usage and providing you with a simple and easy method to estimate the kWh usage of your own heat pump.
Additionally, I’ll explore the actual cost associated with running your heat pump and offer a convenient cost calculator to save you time.
Once we’ve established the energy requirements (kWh) for your heat pump and the associated expenses, we’ll delve into Power Usage (Watts), which will be especially informative if you’re considering equipment like an inverter or a generator to power your heat pump.
Let’s get started.
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How much electricity (kWh) does a heat pump use?
The electricity usage of a heat pump is influenced by several key factors:
- The capacity of the heat pump, indicated by its BTU (British Thermal Units) ratings, or more commonly, its tonnage.
- The age, condition, and efficiency of the heat pump.
- Whether it’s cooling or heating season.
- The usage patterns of the heat pump, such as daily usage duration.
- Other operating conditions, such as climate, thermostat settings, insulation, etc.
For instance, a 2-ton (24,000 BTU) heat pump might consume around 500 kWh of electricity per month during cooling seasons. Conversely, a 5-ton (60,000 BTU) heat pump could use up to 3,500 kWh per month in heating seasons.
As a general guideline, the table below classifies heat pumps based on their tonnage (or BTU rating) and provides estimates of their hourly energy consumption (kWh/hour) for both cooling and heating seasons, as well as the total annual energy consumption (kWh/year) when considering both heating and cooling:
| Heat Pump’s Tonnage or BTU rating | Est. Hourly Energy Consumption (kWh/hour) in the cooling season | Est. Hourly Energy Consumption (kWh/hour) in the heating season | Est. Annual Energy Consumption (kWh/year) — Cooling & Heating |
| 1 Ton (12,000 BTUs) | 0.6 – 0.85 kWh per hour | 1 – 1.6 kWh per hour | 2,100 – 3,400 kWh per year |
| 13,500 BTUs | 0.7 – 0.95 kWh per hour | 1.15 – 1.8 kWh per hour | 2,350 – 3,800 kWh per hour |
| 15,000 BTUs | 0.75 – 1.1 kWh per hour | 1.25 – 2 kWh per hour | 2,600 – 4,200 kWh per hour |
| 1.5 Tons (18,000 BTUs) | 0.9 – 1.3 kWh per hour | 1.5 – 2.4 kWh per hour | 3,200 – 5,100 kWh per hour |
| 2 Tons (24,000 BTUs) | 1.2 – 1.7 kWh per hour | 2 – 3.2 kWh per hour | 4,200 – 6,800 kWh per hour |
| 2.5 Tons (30,000 BTUs) | 1.5 – 2.2 kWh per hour | 2.5 – 4 kWh per hour | 5,300 – 8,500 kWh per hour |
| 3 Tons (36,000 BTUs) | 1.8 – 2.6 kWh per hour | 3 – 4.8 kWh per hour | 6,300 – 10,200 kWh per hour |
| 3.5 Tons (42,000 BTUs) | 2.1 – 3 kWh per hour | 3.5 – 5.5 kWh per hour | 7,400 – 11,900 kWh per hour |
| 4 Tons (48,000 BTUs) | 2.4 – 3.4 kWh per hour | 4 – 6.5 kWh per hour | 8,400 – 13,600 kWh per hour |
| 5 Tons (60,000 BTUs) | 3 – 4.2 kWh per hour | 5 – 7.5 kWh per hour | 10,500 – 17,000 kWh per hour |
Related: How much electricity does an air conditioner use?
These estimations provide a general idea of your heat pump’s hourly and annual energy consumption.
For example, if you have a central 3-ton (36,000 BTU) heat pump, it should typically consume between 1.8 and 2.6 kWh of energy per hour during the cooling season. Assuming it runs for 10 hours daily, this results in a daily energy consumption ranging from 18 to 26 kWh, or approximately 550 to 800 kWh per month.
In the heating season, the same heat pump would consume roughly 3 to 4.8 kWh per hour. Assuming a daily operation of 12 hours, this translates to a daily energy usage of 36 to 58 kWh, or approximately 1100 to 1700 kWh per month.
Over a year, the 3-ton heat pump would consume somewhere in the range of 6,300 to 10,200 kWh of energy.
To calculate the operating costs of your heat pump, these energy consumption estimates can be multiplied by your local electricity rates.
However, before discussing costs, let’s explore more accurate methods to determine your heat pump’s energy consumption.
1- How to estimate the hourly energy use of your heat pump?
As mentioned above, among other factors, the energy use of your heat pump will depend on its efficiency, which is how effectively the unit transforms electrical energy into heating or cooling.
See, The tonnage (BTU rating) of your heat pump indicates its heat exchange capacity, or how much heating or cooling it can provide in an hour.
The electrical energy required by your heat pump to perform this heat exchange within an hour depends on its energy efficiency:
Energy Efficiency = Capacity (BTUs) ÷ Hourly Energy Consumption (Watt-hours/hour)
Manufacturers provide these efficiency values in the form of Energy Efficiency Ratios/Factors, which include:
- A SEER (Seasonal Energy Efficiency Ratio) rating, which reflects the heat pump’s energy efficiency during the cooling season.
- An HSPF (Heating Seasonal Performance Factor) rating, which represents the heat pump’s energy efficiency during the heating season.
To estimate your heat pump’s hourly energy consumption during summer (cooling), you can use the SEER rating with the following formula:
Hourly Energy Consumption in The Summer (Watt-hours/hour) = Capacity (BTUs) ÷ SEER
Hourly Energy Consumption in The Summer (kWh/hour) = (Capacity (BTUs) ÷ SEER) ÷ 1000
And the HSPF rating of the unit can be used to estimate its hourly energy consumption during the winter as follows:
Hourly Energy Consumption in The Winter (Watt-hours/hour) = Capacity (BTUs) ÷ HSPF
Hourly Energy Consumption in The Winter (kWh/hour) = (Capacity (BTUs) ÷ SEER) ÷ HSPF
For example, let’s take a look at this EnergyGuide label on a 5-ton (60,000 BTU) heat pump:
The SEER rating for this heat pump falls between 15.5 and 16. For a conservative estimate of its hourly energy consumption during the cooling season, we’ll use the lower value of 15.5:
Hourly Energy Consumption — Cooling (Watt-hours/hour) = Capacity (BTUs) ÷ SEER
Hourly Energy Consumption — Cooling (Watt-hours/hour) = 60, 000 BTUs ÷ 15.5
Hourly Energy Consumption — Cooling (Watt-hours/hour) = 3870 Wh/hour
Hourly Energy Consumption — Cooling (kiloWatt-hours/hour) = 3.87 kWh/hour
With an HSPF rating of 8.5, we can estimate the heat pump’s hourly energy consumption in the heating season:
Hourly Energy Consumption — Heating (Watt-hours/hour) = Capacity (BTUs) ÷ HSPF
Hourly Energy Consumption — Heating (Watt-hours/hour) = 60,000 BTUs ÷ 8.5
Hourly Energy Consumption — Heating (Watt-hours/hour) = 7058 Wh/hour
Hourly Energy Consumption — Heating (kiloWatt-hours/hour) = 7.05 kWh/hour
As I explain below, these hourly energy use values can be then used to estimate the annual energy consumption of the unit.
2- How to estimate the annual energy use of your heat pump?
The formula for estimating the annual energy consumption of your heat pump can be expressed as follows:
Annual Energy Use (kWh/year) = (Hourly Energy Consumption (cooling) x Average Use Cycle for Cooling (hours/year)) + (Hourly Energy Consumption (Heating) x Average Use Cycle for Heating (hours/year))
Now, these are the variables:
Hourly Energy Consumption (Cooling): This refers to the energy consumption of the heat pump while it’s in cooling mode.
Hourly Energy Consumption (Heating): This represents the energy consumption of the heat pump while in heating mode.
Average Use Cycle for Cooling (hours/year): This figure represents the average number of hours per year during which the heat pump is operating in cooling mode. It accounts for the total cooling season hours.
Average Use Cycle for Heating (hours/year): Similarly, this value represents the average number of hours per year during which the heat pump is operating in heating mode, accounting for the heating season hours.
By multiplying the hourly energy consumption (kWh/hour) in each mode by their respective average use cycles (hours/year) and summing up the results, you can estimate the total annual energy consumption of your heat pump in kilowatt-hours (kWh/year).
It’s essential to recognize that the energy consumption of your heat pump during cooling and heating seasons can vary significantly depending on various factors such as climate, thermostat settings, insulation, and usage patterns.
On the other hand, the number of hours you typically use the heat pump each day will determine the usage cycles for each season.
Nevertheless, the method I described above can provide a reasonably close estimate of the hourly energy consumption of the heat pump for each season.
Now, let’s consider average usage cycles based on the U.S. DOE’s test procedures for measuring the energy use of central ACs and heat pumps, which offer the following rules of thumb:
- The average annual cycle for cooling = 1000 hours/year
- The average annual cycle for Heating = 1600 hours/year
Using these estimates, we can simplify the formula as follows:
Annual Energy Use (kWh/year) = (Hourly Energy Consumption (cooling) x 1000 hours/year) + (Hourly Energy Consumption (Heating) x 1600 hours/year)
To illustrate this, let’s follow up on our previous example:
- Hourly Energy Consumption (cooling) = 3.87 kWh/hour
- Hourly Energy Consumption (Heating) = 7.05 kWh/hour
Now, let’s calculate the total annual energy use:
Annual Energy Use (kWh/year) = (Hourly Energy Consumption (cooling) x 1000 hours/year) + (Hourly Energy Consumption (Heating) x 1600 hours/year)
Annual Energy Use (kWh/year) = (3.87 kWh/hour x 1000 hours/year) + (7.05 kWh/hour x 1600 hours/year)
Annual Energy Use (kWh/year) = (3,870 kWh/year) + (11,280 kWh/year)
Annual Energy Use (kWh/year) = 15,150 kWh/year
While these calculations provide valuable estimates, the most precise way to determine energy consumption is by directly measuring it.
3- How to measure the energy consumption of your heat pump?
For ductless mini-split heat pumps that typically use standard 120 Volts and don’t require a dedicated circuit, you can utilize a plug-and-play electricity meter like the Kill-A-Watt meter to measure their energy consumption accurately.
Simply plug the monitoring device into the electrical outlet, connect your heat pump to it, and press the “kWh” button to obtain real-time energy consumption readings. This method provides a precise assessment of your heat pump’s energy usage over a specific period.
If, for example, you’d like to measure your heat pump’s monthly energy consumption, you could plug the unit into the Kill-A-Watt meter, and check the “kWh” readings 24 hours later.
This would give you the daily energy consumption of your heat pump, which you could then multiply by 30 to determine the monthly energy consumption of the unit.
For larger central heat pumps operating on a 240V dedicated circuit, a device like the Emporia monitor would be needed.
This device would be installed on your main electrical panel and would allow you to access real-time data through a monitoring app on your phone or tablet. However, It’s advisable to have a professional electrician set it up for you.
Nevertheless, here’s an overview of how the Emporia monitor would be installed:
Now that you have a general understanding of your heat pump’s energy consumption in kilowatt-hours (kWh), including how to estimate and measure it, let’s delve into the associated costs of this energy usage.
How much does it cost to run a heat pump?
The cost of running your heat pump will depend on its exact energy consumption (measured in kWh), which in turn depends on the size of the unit, its efficiency, whether it’s cooling or heating, and usage patterns. Additionally, the costs of operating the heat pump will also depend on the cost per kWh ($/kWh) your utility provider is charging:
Cost ($) = Energy Consumption (kWh) x Cost per kWh ($/kWh)
To provide a general guideline, the following table classifies heat pumps based on their capacity (tonnage/BTU rating) and uses the U.S. national average electricity price to estimate the hourly operating costs for these units during both the summer and winter seasons:
| Heat Pump’s Tonnage or BTU rating | Est. Hourly Cost ($/hour) in the cooling season | Est. Hourly Cost ($/hour) in the heating season | Est. Annual Cost ($/year) — Cooling & Heating |
| 1 Ton (12,000 BTUs) | 0.10 – 0.14 $/hour | 0.16 – 0.25 $/hour | 330 – 540 $/year |
| 13,500 BTUs | 0.11 – 0.15 $/hour | 0.18 – 0.28 $/hour | 375 – 600 $/year |
| 15,000 BTUs | 0.12 – 0.17 $/hour | 0.20 – 0.32 $/hour | 410 – 670 $/year |
| 1.5 Tons (18,000 BTUs) | 0.14 – 0.20 $/hour | 0.24 – 0.38 $/hour | 510 – 810 $/year |
| 2 Tons (24,000 BTUs) | 0.19 – 0.27 $/hour | 0.32 – 0.50 $/hour | 670 – 1,080 $/year |
| 2.5 Tons (30,000 BTUs) | 0.24 – 0.35 $/hour | 0.40 – 0.64 $/hour | 850 – 1,350 $/year |
| 3 Tons (36,000 BTUs) | 0.28 – 0.41 $/hour | 0.48 – 0.76 $/hour | 1,000 – 1,600 $/year |
| 3.5 Tons (42,000 BTUs) | 0.33 – 0.48 $/hour | 0.56 – 0.88 $/hour | 1,200 – 1,900 $/year |
| 4 Tons (48,000 BTUs) | 0.38 – 0.54 $/hour | 0.64 – 1.04 $/hour | 1,350 – 2,200 $/year |
| 5 Tons (60,000 BTUs) | 0.48 – 0.67 $/hour | 0.80 – 1.20 $/hour | 1,650 – 2,700 $/year |
For example, in the cooling season, a 5-ton heat pump would consume approximately $0.48 to $0.67 worth of electricity per hour of operation. Assuming a daily operation of 10 hours a day, this would amount to approximately $4.8 to $6.7 per day or roughly $140 to $200 per month.
In the heating season, the same 5-ton heat pump would consume around $0.8 to $1.2 per hour. With a daily operation of 12 hours a day, this would translate to approximately $9 to $14 per day or about $280 to $400 per month.
Over a year, the 5-ton heat pump would typically consume electricity valued at approximately $1,650 to $2,700.
However, it’s important to note that these figures are rough estimates based on the national average cost per kWh, which is approximately 16 cents/kWh ($0.16/kWh). The actual cost per kWh can vary significantly across the country, ranging from 10 to 30 cents/kWh.
For instance, according to the Energy Information Administration (EIA), the average cost of electricity in Wyoming is only 12 cents per kWh, while in Maine, it’s around 30 cents per kWh.
To provide you with more accurate estimates, and to save you time, I’ve created a heat pump running cost calculator.
This calculator takes into account your heat pump’s capacity (Tonnage/BTU rating), your daily usage duration, and the electricity prices in your area and estimates the daily and monthly costs of operating your heat pump:
If you’re considering running your heat pump using a power source other than the grid, the first step is to determine the power usage or wattage of the unit.
How many Amps, Volts, and Watts does a heat pump use?
While the Energy Consumption (kWh) of your heat pump indicates the total amount of electricity it uses over a period, the Power Usage (Watts) measures how quickly the unit consumes electricity.
Click here to learn more about the difference between energy and power.
If you’re trying to size an inverter or a generator that will run your heat pump, you will need to determine the power usage of the unit.
So, how much power, or how many watts does your heat pump use?
Just like its energy consumption, the power usage of your heat pump will also depend on the capacity of the unit. The greater its capacity, the more watts it will require to operate.
For example, while a 2-ton (24,000 BTU) heat pump uses between 2400 and 3000 Watts of power, a 5-ton (60,000 BTU) heat pump may require up to 7500 Watts when running.
Before I show you the correct way to determine the exact power usage of your heat pump, here’s a table that should give you a general idea of the Power Usage (Watts) of heat pumps based on their capacity:
| Heat Pump’s Tonnage or BTU rating | Est. Power Usage in Watts |
| 1 Ton (12,000 BTUs) | 1200 – 1600 Watts |
| 13,500 BTUs | 1300 – 1800 Watts |
| 15,000 BTUs | 1500 – 2000 Watts |
| 1.5 Tons (18,000 BTUs) | 1800 – 2400 Watts |
| 2 Tons (24,000 BTUs) | 2400 – 3000 Watts |
| 2.5 Tons (30,000 BTUs) | 3000 – 3800 Watts |
| 3 Tons (36,000 BTUs) | 3600 – 4500 Watts |
| 3.5 Tons (42,000 BTUs) | 4200 – 5200 Watts |
| 4 Tons (48,000 BTUs) | 4800 – 6000 Watts |
| 5 Tons (60,000 BTUs) | 6000 – 7500 Watts |
While these rough estimates should give a good idea of the wattage of your heat pump, please note that some heat pumps are equipped with inverter technology, which means their power usage is variable and may not reach the figures provided in the table.
Furthermore, these figures represent the “Running” wattage of the heat pumps and do not account for their “Starting” wattage.
Like any other appliance that operates on a motor (refrigerators, pumps, fans, washing machines, etc..), a heat pump demands significantly more power during its startup phase. Once the heat pump is running, its power usage falls within the ranges indicated in the table.
However, it’s worth mentioning that this rule doesn’t apply to inverter-equipped heat pumps. These systems have motors capable of regulating their speed, resulting in a gradual increase in power usage during startup, rather than a spike.
In any case, let me explain the correct way to determine how many watts your heat pump is capable of using.
How to determine the wattage of your heat pump?
Electrical Power, also referred to as Wattage, is the product of Electrical Current (Amperage), which is measured in Amps, and Electrical Potential (Voltage), which is measured in Volts.
Power Usage (Watts) = Current (Amps) x Voltage (Volts)
Click here to learn more about Amps, Volts, Watts, and the relationship between these units.
The Amperage and Voltage of your heat pump are usually specified by the manufacturer on the nameplate, and could therefore be used to accurately determine the power usage of your unit.
Before I give you an example, it is important to first understand the components in your heat pump that require electricity to operate.
Whether it’s a ducted central system or a ductless mini-split system, there are 3 main components within your heat pump system that draw power:
- The compressor, which serves the critical role of compressing and pumping the refrigerant within the heat pump’s coils to facilitate heat exchange.
- The outdoor fan motor, which drives the fan on the condenser (outdoor) unit of your heat pump and allows heat to be exchanged with the exterior.
- The indoor fan motor, which drives the fan on the air handler (indoor) unit of your heat pump, allowing it to blow warm or cool air to the interior. For multi-zone mini-split heat pumps, there will be an air handler for each zone, and will therefore be an indoor fan motor drawing power for each zone.
When your heat pump operates and produces warm or cool air, all three of these components draw power. Consequently, you can calculate the “Running” Wattage of your heat pump as follows:
Running Wattage (Watts) = Compressor’s Running Wattage (Watts) + Outdoor Fan’s Running Wattage (Watts) + Indoor Fan’s Running Wattage (Watts)
The running wattage of each component can be calculated using its Amperage (Amps) and Voltage (Volts).
The amperage and voltage specifications for the compressor and outdoor fan can be located on the nameplate of the outdoor unit since these components are situated outside.
Conversely, the electrical details for the indoor fan motor are typically provided on the nameplate of the indoor unit.
However, as mentioned before, the running power usage of your heat pump is not the only wattage figure you need to be concerned about. In fact, when sizing equipment that’ll run these units, your number one concern should be the “Starting” Wattage of the heat pump rather than its “Running” Wattage.
This Starting Wattage can be calculated as follows:
Starting Wattage (Watts) = Compressor’s Starting Wattage (Watts) + Outdoor Fan’s Running Wattage (Watts) + Indoor Fan’s Running Wattage (Watts)
To illustrate, let’s examine an example involving a 4-ton (48,000 BTU) central heat pump. The image below displays the nameplates on the outdoor and indoor units of the heat pump:
On these nameplates, the manufacturer specifies the following:
- Voltage: It is indicated as 208/230 Volts, which means the heat pump can function on either a 208 Volts 3-phase circuit or a 230 Volts split-phase circuit. In the U.S., residential central heat pumps typically operate on a 230 Volts split-phase circuit.
- A Compressor RLA of 19.9 Amps: RLA stands for Rated Load Amps and represents the maximum current (measured in Amps) that the compressor draws during normal operation. RLA represents the compressor’s maximum “Running” Amperage.
- A Compressor LRA of 109 Amps: LRA stands for Locked Rotor Amps, and it represents the maximum amount of current that the compressor may potentially require during startup. The LRA rating represents the maximum “Starting” Amperage of the compressor.
- An Outdoor Fan Motor FLA of 1.2 Amps: FLA stands for Full Load Amps, and it represents the maximum amount of current that the fan motor may require when it’s running.
- An Indoor Fan Motor FLA of 6 Amps: This rating represents the maximum amount of current that the indoor fan may require during operation.
The Voltage and RLA ratings can be used to calculate the “Running” Wattage of the compressor:
Compressor’s Running Wattage (Watts) = RLA (Amps) x Voltage (Volts)
Compressor’s Running Wattage (Watts) = 19.9 Amps x 230 Volts
Compressor’s Running Wattage (Watts) = 4577 Watts
The Voltage and LRA ratings can be used to calculate the “Starting” Wattage of the compressor:
Compressor’s Starting Wattage (Watts) = LRA (Amps) x Voltage (Volts)
Compressor’s Starting Wattage (Watts) = 109 Amps x 230 Volts
Compressor’s Starting Wattage (Watts) = 25,070 Watts
The Voltage and FLA ratings of the outdoor fan can be used to calculate its “Running” Wattage:
Outdoor Fan’s Running Wattage (Watts) = FLA (Amps) x Voltage (Volts)
Outdoor Fan’s Running Wattage (Watts) = 1.2 Amps x 230 Volts
Outdoor Fan’s Running Wattage (Watts) = 276 Watts
The Voltage and FLA ratings of the Indoor fan can be used to calculate its “Running” Wattage:
Indoor Fan’s Running Wattage (Watts) = FLA (Amps) x Voltage (Volts)
Indoor Fan’s Running Wattage (Watts) = 6 Amps x 230 Volts
Indoor Fan’s Running Wattage (Watts) = 1380 Watts
Now, to calculate the Running Wattage of the entire 4-ton heat pump unit, we add up the “Running” wattages:
Running Wattage (Watts) = Compressor’s Running Wattage (Watts) + Outdoor Fan’s Running Wattage (Watts) + Indoor Fan’s Running Wattage (Watts)
Running Wattage (Watts) = 4577 Watts + 276 Watts + 1380 Watts
Running Wattage (Watts) = 6233 Watts
And the Starting Wattage of the unit is calculated as follows:
Starting Wattage (Watts) = Compressor’s Starting Wattage (Watts) + Outdoor Fan’s Running Wattage (Watts) + Indoor Fan’s Running Wattage (Watts)
Starting Wattage (Watts) = 25070 Watts + 276 Watts + 1380 Watts
Starting Wattage (Watts) = 26,726 Watts
It’s essential to clarify that these calculations represent worst-case scenarios, and under normal circumstances, neither the Running Wattage nor the Starting Wattage of the heat pump should typically reach these maximum values.
However, for sizing equipment like inverters or generators, these worst-case figures should be considered.
