How Many Watts Does a Window AC Use?


When the summer heat wave hits, many people turn to window AC units to find relief. But as these units hum away, how much energy are they consuming? 

On average, traditional window AC units guzzle between 500 and 1500 watts of energy. It’s a broad range, contingent on factors like size, model, and unit efficiency. 

As energy conservation and cost savings grow increasingly important, understanding the power demands of our appliances becomes essential. Here, we delve into the details of window AC energy consumption to help you make informed decisions. 

Understanding BTU, Rated Watts, Running Watts, and Watt-Hours

British Thermal Unit (BTU)

A British Thermal Unit, commonly abbreviated as BTU, measures the amount of heat required to raise the temperature of a pound of water by one degree Fahrenheit. In the context of air conditioners, BTU ratings provide insight into the unit’s cooling capacity. 

Essentially, the higher the BTU rating, the more space an AC unit can cool effectively. For example, the EcoFlow WAVE 2 offers an impressive 5100 BTs of cooling and 6100 BTUs of heating. 

Running Watts

Running watts denote the average power an appliance uses during its operation to run continuously. This metric is very important to determine the power consumption of devices, which in turn helps you decide whether or not you can power them and for how long.

Starting Watts

While running watts refer to the electricity consumed while a device runs, some appliances have a higher starting wattage to turn on. Also known as peak or surge wattage, starting watts is a metric referring to the amount of power that’s necessary momentarily to get the appliance running. For example, your window AC unit may have a higher starting wattage when compared to its running wattage, but this amount of power is only required for a short time to turn the appliance on.


Watt-Hours are a cumulative representation of energy consumption over time. A watt-hour signifies the total energy used if an appliance runs for one hour at one watt. It’s an invaluable measure for those looking to estimate their energy expenditure over time, allowing for more informed decisions about energy usage and budgeting. 

How Many Watts Does a Small Window AC Use?

Small window air conditioners are popular for cooling individual rooms or smaller living spaces. Small window AC units typically possess a cooling capacity ranging from 5,000 to 8,000 BTUs. Given the size and capacity of these units, their power consumption is relatively modest. 

On average, a small window AC unit will consume between 500 to 800 watts of power when operating at full capacity. Of course, the actual energy consumption can vary based on factors like the unit’s efficiency rating, age, maintenance condition, and external temperatures.

To determine the energy consumption of a particular small window AC model, try checking the unit’s specification label or consult the manufacturer’s documentation. Still, as a general guideline, these figures offer a ballpark range for homeowners keen on understanding the energy demands of their small window AC units.

How Many Watts Does a Large Window AC Use?

Many people opt for larger window air conditioning units when it comes to cooling larger spaces or rooms with high ceilings. These AC units deliver a more substantial cooling capacity and, as a result, consume more energy than their smaller counterparts.

Large window AC units typically have a cooling capacity ranging from 10,000 to 25,000 BTUs. Given their enhanced capabilities, these units demand more power. Generally, a large window AC can use anywhere from 900 to 1,500 watts, depending on its BTU rating and efficiency. 

However, this isn’t a fixed rule. Some high-efficiency models might consume slightly less power for the same cooling capacity, while older or poorly-maintained units might consume more.

You can typically determine the exact power consumption of a specific large window AC model by referencing the product’s specification label or the manufacturer’s documentation. Nevertheless, these figures offer a good reference point for those looking to gauge the energy requirements of their large window ACs.

How to Calculate How Much Energy Your Window AC Consumes

Thankfully, with a bit of math, gauging how much energy your window AC unit consumes isn’t as complex as it sounds. 

First, you’ll want to identify the power consumption of your AC, which is typically mentioned on the product label or within the user manual.

Then, multiply its wattage by how many hours you run it. For instance, an AC that uses 1,200 watts operating for 5 hours daily consumes 6,000 watt-hours or 6 kWh daily. 

When considering its monthly footprint, you’d multiply this daily figure by how many days you use the AC throughout the month. So, if you’re running the AC for 20 days a month, it would amount to 120 kWh in consumption.

The real clincher comes when you link this to your energy bill. By multiplying your monthly kWh figure by the cost of electricity per kWh, you can estimate the monthly cost of operating your AC. 

Taking our previous example, if electricity costs $0.10 per kWh, operating that AC could add about $12 to your monthly energy bill. 

Frequently Asked Questions

How Many Watts Does a 12000 BTU Window Unit Use?

A 12,000 BTU window unit typically consumes between 1,000 to 1,500 watts. However, exact wattage can vary based on the unit’s efficiency, age, and operational conditions. Checking the product label or manual will provide specific details.

Final Thoughts

Understanding the intricacies of window AC units is crucial for an informed purchase. As we’ve covered, wattage varies based on factors like size, model, and BTU rating. 

Browse our EcoFlow WAVE 2 Collection for options that can assist in monitoring and managing your energy needs, ensuring you optimize your consumption patterns. 

Want to make the most of your portable air conditioner? If you’re operating the EcoFlow WAVE 2 Portable AC using a EcoFlow DELTA Series Portable Power Station like the EcoFlow DELTA Pro, you could enjoy up to 24 hours of cooling power on Eco Mode!

Make an eco-friendly and cost-effective choice when it comes to your portable air conditioner. Check out the EcoFlow WAVE 2 today.

EcoFlow is a portable power and renewable energy solutions company. Since its founding in 2017, EcoFlow has provided peace-of-mind power to customers in over 85 markets through its DELTA and RIVER product lines of portable power stations and eco-friendly accessories.

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