How big of a generator do I need to run a 8,000 BTU air conditioner? (Is your generator capable of running AC)

To power an 8,000 BTU air conditioner with a generator, ensure you know the unit’s size and wattage specifications, factors like usage duration to determine runtime and fuel needs, and account for climate conditions.

Why do you need a generator for your air conditioner in the first place?

The necessity of having a generator for your air conditioner stems from various scenarios and situations where a stable and reliable power source becomes indispensable.

This essential need becomes particularly evident when considering unpredictable events such as power outages, camping trips, or emergencies.

From unpredictable power outages to enhancing camping experiences and ensuring emergency preparedness, a generator becomes a versatile solution, providing a continuous and reliable power source for your air conditioning needs.

The table outlines key scenarios where having a generator for your air conditioner is essential:

Scenarios Description
Unpredictable Power Outages Power outages can occur unexpectedly due to storms, technical issues in the grid, or other unforeseen circumstances.
Camping Trips and Remote Locations For those who enjoy camping or find themselves in remote locations, having a portable air conditioner powered by a generator enhances the overall camping experience. This setup provides a reliable and adjustable climate control solution, ensuring comfort throughout the trip, regardless of the outdoor conditions.
Emergency Preparedness In emergency situations, where access to a stable power grid may be compromised, a generator proves invaluable. Whether facing natural disasters or unforeseen events, a generator acts as a dependable source of electricity

While recognizing the need for a generator, determining the appropriate size for your specific air conditioner becomes the next crucial step.

In the example of an 8,000 BTU air conditioner, assessing the generator’s capacity involves considering factors such as the startup wattage surge, operational efficiency, and the overall power requirements of the air conditioner.

How big of a generator do I need to run a 8,000 BTU air conditioner?

Determining the appropriate generator size to power an air conditioner involves consideration of various factors:

Consideration Description
Air Conditioner Size and Wattage To effectively power your air conditioner unit you need to know its specifications, including its size and wattage. This is important because you need a generator with sufficient capacity to meet the power demands of the air conditioner.
Usage Duration Assess how many hours per day the air conditioner will be in operation. This factor influences the overall energy consumption, helping determine the generator’s runtime and fuel requirements.
Climate Conditions Take into account the climate of your location or the environment you plan to use the air conditioner in. Extreme temperatures can impact the air conditioner’s efficiency and affect the generator’s performance.

Size and wattage of the air conditioner unit

To determine the appropriate generator size for an 8,000 BTU air conditioner, you need to consider the unit’s starting wattage and running wattage.

Consideration Description
Starting Wattage Air conditioners typically have a higher starting wattage, known as the surge or inrush current, required when the compressor kicks in. Check the air conditioner’s manual or specification sheet for this information.
Running Wattage The running wattage is the continuous power needed to keep the air conditioner running once it has started. This information should also be available in the air conditioner’s manual or specifications.

To determine the generator size needed, consider both the starting wattage (higher at the initial compressor kick-in) and the running wattage (continuous power to keep the unit running).

Once you have both the starting and running wattage, add a safety margin to ensure your generator can handle the load comfortably.

A common rule of thumb is to choose a generator with a wattage rating that is at least 20% more than the total running wattage of the air conditioner.

So, if the running wattage of your 8,000 BTU air conditioner is 600 watts, you might consider a generator with a rating of at least 600 × 1.2 = 720 600×1.2=720 watts.

Going around the other way

If you don’t have the information about the starting wattage and running wattage, you can still make an estimate.

The wattage (W) of an air conditioner can be calculated using the formula:


Your AC Wattage = 8,000 x 0.293 = 2,344 Watts

The Energy Efficiency Ratio (EER) is a measure of how efficiently an air conditioner uses electricity.

It is calculated by dividing the unit’s cooling capacity (in BTUs) by its power consumption (in watts). A higher EER indicates greater energy efficiency.

For example, for the 2,344 Watts above, the EER of such an air conditioner of 8,000 BTU would be 3.4:

8,000 BTU/h / 2,344 Watt/h =  3.4 EER


To calculate the Energy Input in Watts, use this formula:

Below we have calculated the generator recommended size, based on the EER for an 8,000 BTU air conditioner:

EER (8,000 BTU AC) Recommended Generator Size Available on Amazon
7 1200-watt generator and above Buy it
8 1000-watt generator and above Buy it
9 900-watt generator and above Buy it
10 800-watt generator and above Buy it
11 800-watt generator and above Buy it
12 700-watt generator and above Buy it

This is in theory only. This table is to give you an idea of how a 8,000 BTU air conditioner wattage is computed with regards to the unit’s EER.

Always refer to the specific EER rating of your air conditioner and consider both starting and running wattage when selecting a generator to ensure efficient and reliable operation.

How many hours a day will the AC be used?

Aside from power consumption, another important factor is time. You need to know how long you’re going to use your AC off the grid.

Every portable generator has different charging capacity so make sure you optimize your AC usage.

The most accurate way to determine how many watts your specific AC uses, is to use a watt meter to take measurements of your unit’s power usage.

Watt meters, like this Poniie PN2000 Plug-in Kilowatt electricity usage monitor, are plugged into the power socket and then your air conditioner is plugged into the watt meter.

This meter will then give you a digital read-out of the amount of kilowatts that your air conditioning unit uses per hour.

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Determine the climate on where you are using the generator

The climate and environmental conditions play a significant role in the performance and efficiency of generators and air conditioners.

Here are some considerations when using a generator and air conditioner in different climates to ensure optimal performance of both the generators and air conditioners:

Cold Climate

Ensure that your generator is rated for cold weather use. Cold weather won’t impact the air conditioner directly.

Generator Air Conditioner
  • Use a winter-grade fuel or add a fuel stabilizer to prevent fuel gelling
  • Keep the generator in a sheltered, dry area to protect it from snow and ice
  • It is better to check the manufacturer’s specifications to verify the operating temperature range of the air conditioner

Hot Climate

High temperatures can affect the cooling system of generators. However, air conditioners are designed to work in hot climates, but excessive heat can still affect their efficiency.

Generator Air Conditioner
  • Ensure that the generator is adequately ventilated to prevent overheating
  • Regularly check the oil and coolant levels
  • Keep the air conditioner unit shaded to prevent it from overheating
  • Regularly clean or replace air filters

Humid Climate

Humidity can contribute to corrosion of generators, and can also affect the cooling efficiency of air conditioners 

Generator Air Conditioner
  • Consider placing the generator in a dry, well-ventilated area
  • Regularly inspect and clean the generator to prevent rust and corrosion.
  • Invest in an air conditioner model with dehumidification features
  • Regular maintenance (cleaning or replacing filters) is vital to prevent mold and mildew

Keep an eye for the AC power surge

Always take into account an additional 20% on top of the rated power of the air conditioner.

This is to prevent the inefficient use of generators, especially during the crucial moment when the startup wattage surge from the AC comes into play

The startup wattage surge, often referred to as the “inrush current,” is a critical consideration when choosing a generator to power appliances like air conditioners.

This surge occurs when the air conditioner’s compressor initiates its operation or during the initial usage of the AC system.

It represents a temporary spike in power demand that, if not properly accounted for, can lead to issues such as generator overload, inefficiency, and potential damage to both the generator and the air conditioning unit.

By incorporating an additional 20% margin above the rated power of the air conditioner, you create a buffer that accommodates the inrush current seamlessly.

This precautionary measure ensures that the generator is adequately sized to handle the sudden power demand during the startup phase of the air conditioner.

It not only prevents potential overloading but also promotes the overall longevity and efficiency of the generator system.

2023 Outdoor Participation Trends: A growing thrive in outdoor activities and power needs

In a 2023 Outdoor Participation Trends Report by the Outdoor Industry Association (OIA), it was revealed that in 2022, outdoor recreation participants increased by 2.3% to a record 168.1 million, comprising 55% of the U.S. population aged 6 and older.

This growth has persisted for eight consecutive years, adding 14.5 million participants since January 2020.

(While 2022 saw record participation rates, the number of outings per participant declined for the first time since the onset of the pandemic in 2020.)

That is a huge number of people who spent their time outside and off the grid. Now think about how many people have portable generators and air conditioners with them to keep them comfortable.

Using a 5,000 BTU AC? Check this article: How Many Watts Does A 5,000 BTU AC Use? (Can Your Generator Run It)

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