What size generator do you need to run an air conditioner?

Power outages are inconvenient and when you need essential appliances like your home air conditioner to be running, a suitably-sized generator is a possible solution.

A power outage can be one of the most unpleasant experiences, especially if you were running your air conditioning unit for cooling purposes. Without power, your air conditioner will not operate and you may have to endure the heat.

Luckily for some people, this is when their backup power supply comes in handy. A generator can power an air conditioner, but is the size of your generator suitable for the size of your air conditioning unit?

Running an air conditioner with a generator

Air conditioners are known for their hefty power consumption. It takes a lot of power to keep an air conditioner operational and have it run seamlessly. The amount of power a unit runs on depends on the size of the unit’s cooling capacity.

Cooling capacities differ and therefore, it is essential that you know the size of your unit and how many watts it consumes in order to determine what size generator it needs to operate, in times of power-loss emergencies.

What size generator do you need to run an air conditioner?

A power cut can be extremely inconvenient, but fortunately, some people have generators to power up their homes and some essential appliances when this happens.

If you want to power up an air conditioner, you need a generator that can withstand and provide the amount of watts needed to power the unit.

Air conditioners differ in BTU size cooling capacity, some are small, starting from around 5 000 BTUs while other units are larger, with around 12 000 BTU’s, equalling 1 ton.

Central air conditioners that cool your home are typically large, starting from 1 ton, but because one size does not fit all, generators that cool larger units typically have power outputs of between 7 000 watts and 20 000 watts, with most in the 13 000 to 18 000-watt range.

Depending on the size of your unit in tons, the generator you need can be up to 20 000 watts. Bigger generators can be beneficial for powering the whole home while accommodating the demands of appliances such as central air conditioners.

Below are two examples of heavy-duty generators that can power an air conditioner.

Generator brand Description Amazon price
Champion Power Equipment

Buy it on Amazon
·   12 000 watt running power

·   15 000 watt starting power

·   Portable generator

·   Electric start

·   Lift Hook for safe and easy transporting and keeps track of voltage, hertz, and run-time

$2 998.99

Buy it on Amazon
·   Dual fuel technology that can run on propane or gasoline

·   12 000 watts starting power

·   9 500 watts running power

·   8 hours run-time

$1 399.00

Air conditioner sizes and matching average generator size

AC unit size (Tons) Generator size (kW)
1.5 tons 6kW
2 tons 8kW
2.5 tons 10kW
3 tons 12kW
3.5 tons 14kW
4 tons 15kW
5 tons 18kW

How to run your air conditioner with a generator without using the generator too much

To be able to run your air conditioner reasonably using your generator, you need to apply some restrictions to ensure the unit does not overtax your generator.

Use your air conditioner only when the temperatures are unbearable, as this can save generator power. Have only one of the units running in your home at a time, and never when no one is occupying a space.

Do not switch your air conditioner on and off repeatedly, as this can waste valuable power.

What about generator noise?

Generators are generally noisy devices, and some people might be concerned about the level of noise a generator unit might produce. Some municipalities and regions have restrictions regarding the level of noise permitted for generators.

If you are concerned about breaking regulations, check your  local regulations and your Homeowners Association can help you choose a generator that is well-suited to your area.

Every generator does, however, make some level of noise, so be prepared for this.

Calculating the total wattage you may need in a generator

If you have plans to invest in a generator for powering up your air conditioner, you can calculate the total wattage you need in a generator.

This can be done by adding the running wattage of each appliance in your home and the starting wattage of each appliance (running wattage multiplied by three).

The result will give you an idea of the size of generator you need to sufficiently keep your home and your air conditioner operation during outages.

Leave a Comment