How much does an air conditioner consume?

An air conditioner's consumption mainly depends on its cooling (or heating) capacity, the device's energy efficiency and the number of hours of use. Factors such as the climate, the home's insulation and the set temperature can also significantly affect actual consumption.

As a rough guide, a domestic 12,000 BTU air conditioner in a high energy class consumes between 400 and 700 kWh per year. At an electricity price of 0.30 €/kWh, that corresponds to a yearly cost of roughly 120 to 250 euros.

However, consumption can vary considerably from one home to another. Use the calculator below to estimate your air conditioner's yearly consumption and bill cost based on its specs and your usage habits. Once you have the result, you can check whether your electricity offer is competitive or whether cheaper alternatives exist.

Air conditioner consumption calculator

Usage mode

Select the air conditioner type

Pick a type to start from typical values, then customise the inputs

Select your region
Energy class
6.10 ≤ SEER < 8.50
For the same capacity, a higher class offers greater efficiency (SEER/SCOP) and therefore lower consumption
8 h
024
How many hours a day, on average, you run the air conditioner
4 months
012
How many months a year you use it, for example 3-4 months in summer
12,000 BTU/h
048,000
The unit's capacity, shown on its label. Typically around 9,000 BTU for a bedroom and 12,000-18,000 for a living room
– €/kWh
0.001.00
The energy price shown on your bill, in €/kWh. Make sure to include the PUN value if your offer is indexed

Estimated yearly cost

–

Estimated yearly consumption– kWh
Electrical power drawn– kW

Results are indicative estimates based on the values entered and a representative SEER/SCOP value for each energy class. Actual consumption varies with the model, the set temperature and the home's insulation.

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How air conditioner consumption is calculated

An air conditioner's consumption varies over time and depends mainly on the amount of cooling (or heating) the room requires and on the efficiency with which the system produces it. The two key variables are therefore the home's thermal demand and the device's energy efficiency.

In residential settings and on European energy labels, the annual consumption estimate is normally based on the SEER for cooling and the SCOP for heating, indicators that represent the air conditioner's seasonal efficiency. These values make it possible to convert the cooling or heating capacity into electricity consumed on an annual basis.

What are SEER and SCOP?

SEER (Seasonal Energy Efficiency Ratio)
Seasonal average efficiency indicator for cooling that measures the ratio between cooling produced and electricity consumption over an entire cooling season
SCOP (Seasonal Coefficient of Performance)
Seasonal average efficiency indicator for heating that measures the ratio between heat produced and electricity consumption over an entire heating season

From here on we focus on cooling mode, but the formulas are identical for heating: simply swap the SEER with the SCOP. To estimate consumption, you take the cooling capacity and divide it by the SEER, obtaining the average electrical power drawn: the higher the SEER, the less electricity is needed for the same cooling.

Electrical power (kW) = Cooling power (kW) ÷ SEER

Cooling power represents the air conditioner's ability to remove heat from the room per unit of time. It is a measure of the system's thermal size, not of electricity consumption. This quantity is often expressed in BTU/h.

What is a BTU?

BTU/h (British Thermal Unit per hour)
A unit of thermal power that indicates the amount of heat the air conditioner is able to remove from or add to the room per unit of time (typically one hour). 1 BTU/h equals about 0.293 W, so 12,000 BTU/h corresponds to roughly 3.5 kW of cooling or heating

Multiplying this electrical power by the running time gives the energy consumed, and from that the cost:

Consumption (kWh) = Electrical power (kW) × Hours per day × Days of use
Cost (€) = Consumption (kWh) × Energy price (€/kWh)

It is important to note that the result is an estimate of consumption under typical operating conditions, not a precise measurement. Actual consumption can vary depending on compressor behaviour, the outdoor temperature, the home's insulation level and the set temperature.

How to reduce air conditioner costs

The cost of running an air conditioner depends directly on the electricity it consumes, so reducing the bill doesn't come down to a single factor but to optimising the system's three main variables: the unit's efficiency, how intensively it is used, and the room's thermal load.

The first thing to act on is the air conditioner's energy efficiency. For the same cooling power, a model with a higher SEER/SCOP consumes less electricity to deliver the same level of comfort. The difference between energy classes can translate into significant variations in the annual bill, especially with prolonged use during the summer months.

European energy label of an air conditioner with SEER and SCOP scales
  • 1Measures the seasonal cooling efficiency
  • 2Measures the seasonal heating efficiency
  • 3Indicates the noise levels in decibels of the indoor and outdoor units
  • 4Map of Europe divided into three zones (warm, average, cold) and the respective heating consumption
Template of the European Union energy label for air conditioners, used to illustrate the seasonal efficiency classification and some of the device's technical specifications.

A second decisive factor is managing the home's thermal load. Improving insulation, reducing direct sun exposure and limiting warm-air infiltration reduces the amount of cooling the system needs. The set temperature also has a direct impact on consumption: every degree lower increases the work required of the compressor and therefore the electricity used.

A third aspect concerns how the unit is used, which significantly affects the final cost. Running continuous programmes at a stable temperature is generally more efficient than frequent on/off cycles. In inverter systems, keeping a constant temperature lets the compressor work in a modulated regime, reducing consumption peaks.

One last element that is often underestimated is the price of electricity, which directly affects the final cost regardless of the air conditioner's efficiency. For the same kWh consumption, even relatively small changes in the energy price can translate into significant differences on the annual bill. For this reason, beyond optimising the unit and its use, it is essential to review your electricity offer and compare it with more competitive alternatives.

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Frequently asked questions

How much does an air conditioner consume per hour?

Hourly consumption depends on the model's power and efficiency, but on average a domestic 9,000-12,000 BTU air conditioner in a good energy class draws about 0.4-0.7 kW. That corresponds to roughly 0.4-0.7 kWh for each hour of operation. At an energy price of 0.30 €/kWh, the hourly cost is indicatively between 12 and 21 cents.

How much does it cost to run the air conditioner all day?

A 12,000 BTU unit in class A++ running continuously can consume on the order of 10-14 kWh per day, depending on ambient conditions and the temperature setting. That is equivalent to about 3-4 € per day at an average energy price of 0.30 €/kWh. The actual value varies with the climate, the home's insulation and the model's efficiency.

Is it better to switch off the air conditioner or leave it on?

In general, for short absences it is more efficient to keep the air conditioner on at a slightly higher temperature, avoiding the consumption peaks needed to bring the room back to temperature. For long absences it is better to switch it off. Inverter systems further reduce the difference, modulating power to maintain the temperature with more stable consumption.

How many BTU do I need for my room?

The size of the air conditioner depends on the floor area and the room's thermal load. As an average estimate, you need about 340-380 BTU per square metre. A 20 m² room generally needs about 9,000 BTU, while rooms between 30 and 35 m² typically need 12,000-18,000 BTU. Factors such as sun exposure, the number of windows and ceiling height can significantly increase the requirement.

How much does the energy class affect consumption?

The impact is significant. For the same cooling capacity, a high-efficiency air conditioner can consume up to 30-40% less than a less efficient model. Over a multi-year horizon, this difference has a substantial effect on the total cost of use and often offsets the higher initial price.

How can I reduce the air conditioner's bill?

Reducing costs depends on three main levers: choosing an efficient model, reducing the home's thermal demand and optimising usage habits. Another often decisive factor is the price of energy: comparing electricity offers and selecting a cheaper tariff directly reduces the cost of every kWh consumed, regardless of the type of air conditioner used.