What Size Generator Do I Need to Run AC?

  • By: Umer.A
  • Date: October 10, 2021
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What Size Generator Do I Need to Run Ac

A 4000 watts generator can run a 1.5 ton AC easily. When generators are required to run AC in hot climates, the ultimate sizing of the generator should be considered. We have listed down the generators’ types to help you buy the most suitable generator for running your AC.

Consider The Size of AC You Want to Run?

Installing the generator is a great idea. Especially for individuals living in hot climates, to ensure the working of air conditioners.

Before buying, you need to consider the size of AC you want to run on it and the type of generator.

Backup generators come in different sizes of around 5-50 kilowatts. So, these portable generators work well for small AC’s. In contrast, industrial-sized generators work well to run central air conditioners in huge buildings, data centers, business centers, etc.

For an air conditioner unit, you need to look for its tones, Amps, or BTUs. If you cannot find that, check the label over its unit. You may check out the breaker of your AC that ranges between 30, 40, or 50 Amp.

Moreover, if your AC is a 3-ton with 36000 BTUs, you need a 14KW generator. If you own a 4-ton air conditioner with 48000 BTUs, you need a 17KW generator. And for a 5-ton AC unit, you need a 20KW generator.

Know The Available Generator Types

There are two different types of generators available on the market. The first type is portable generators that are easy to move from one place to another. The second type is standby generators installed outdoors. They are connected through power lines.

The power of portable generators is around 12000 watts. The machine does not push the wattage limit even if you run large air conditioners on it. These generators don’t need much maintenance. The wattage consumption with these generators does not exceed, so you spend less money.

Standby generators, comparatively, are expensive. They come with the extra power to run huge units without any hassle. But you need to maintain them properly.

Understand How the Generators Get Sized

The generators’ units are available in various sizes. The size is not about physical dimensions; it denotes the electrical output of the generators. Electrical production represents the power in watts or kilowatts.

Backup generators are available in different sizes, which range between 5-50 kilowatts. The portable generators are perfect for RV, small offices, parties, and more.

The generator size is determined by the size of your AC, fuel used, wattage requirements of the appliances, and more.

Small-sized generators come in 5-12KW, which is perfect for small essential appliances. However, if you plan on running AC on this generator, this won’t work indeed.

Medium-sized generators come in 12-20KW, which works well for powering essential devices.

Lastly, whole house generators are available in 20-50kW, which works well for powering all appliances and electronics at home.

What’s Average Air Conditioner Wattage?

Different air conditioner units on the market come in a wide range of wattages. However, the air conditioners with energy-efficient features require around 2000 watts.

The older and larger air conditioners come with less efficiency and need around 10000 watts.

Don’t rely on the size of your AC or the average size seen on the internet. Instead, it is essential to check the accurate calculation of watts required by your unit.

Consider The Outside Temperature

At times of increased humidity and temperature outside, you need enough power to start the air conditioner. This power leads to reduced output of the generator.

Moreover, it indicates the need for high power to run the air conditioner. On the other hand, the generator produces low energy ratings due to the high temperature.

The air conditioners come with a steady input. They are measured for 35 degrees Celsius outdoors and 27 degrees Celsius indoors for 50% humidity.

High temperature raises the electrical energy required for the device. Choose the popular average-sized generators which are trendy in fuel efficiency and dimensions.

Consider a temperature that works well for the device and suits the air conditioners.

Outside Temperature

How Many ACs Can Run on A 20-Kva Generator?

A generator with 20-kVA can run around six air conditioners which consume around 2500 watts of power for each AC. A 20kVA generator is equivalent to about 16000 watts. So, assume a power factor of approximately 0.8.

The 20-kVA generator has a high capacity. Hence, you need to decide the number based on AC which efficiently runs on such a generator.

You must know the input capacity and the overall power value consumed by your AC unit. This requires a specific calculation. For instance, your air conditioner consumes around 2500 watts of power based on value; there are high chances of running several air conditioners at once on a generator.

Plus, it’s best to take someone’s opinion and get professional guidelines when buying the right size generator for running the AC.

How Much Is Kva Generator Required for A 1.5-Ton Ac?

With a vast range of generators available on the market, you need the one that works well for running AC.

For instance, generators with 7.5kVA can support around 6000 watts. Whereas generators with 3.5kVA are capable of supporting 2800 watts having a 0.8 power factor.

It also depends on the power consumption of 1.5 tons AC. So, consider multiple factors while buying the right generator size.

Will A 6500-Watt Generator Run Central Air?

A 6500-watt generator is more potent for residential use. However, a 6500 watts generator can efficiently run all average-sized air conditioners for people who run a central air conditioner.

You need to check the watts required by the central air conditioner. It is either written on an AC unit or check the model of your AC online.

What Size Generator Do I Need to Run A 2 Ton Ac Unit?

A generator with 10kVA is ideal for running a 2-ton AC unit. The 2-ton AC unit consumes around 3-3.5 kVA of power, approximately 12-15 amps. In addition, the starting jerk load touches around 2.5-3 times which is about 30-40 amps.

Is It Safe to Run Ac on A Generator?

Yes, it’s safe to run AC on a generator, but there are several factors you need to consider too. Standby generators serve as an excellent option for running AC, but you need to research before investing in one.

The first thing to consider for running AC is to buy the right size generator and its power capacity at once. Small generators support 3000-4000 watts, while large generators support 10kW to 15kW.

Next, you need to consider whether you plan to run a single air conditioner or more.

If you power different machines and the AC, you need to be safe and choose a massive generator with enough power.

Which Generator Is Best for Ac?

A generator with 4000 watts results in enough electricity to run 10000 BTUs AC. You can also power different appliances with such generators.

Get your hands on standby generators as they are the best for running your air conditioner units. They come with huge power wattage to run the AC. Portable generators, however, come with less wattage, so you might not be able to use them for AC.


Choose the right-sized generator for running the AC as per your needs. There will not be any blackouts because of overloading. In addition, it offers high durability, offers improved performance, and enhances personal safety.

So, what are you waiting for? Get your hands on the right size generator based on your needs without any further delay.