What Size Generator to Run Air Conditioner? (know The Facts!)

Air conditioning is not a luxury in the scorching summer. It is necessary. If you are living in an RV or an off-grid farmhouse, a generator can make your life easier. 

Apart from off-grid living, you should have a backup generator for the blackout. Different types of generators are available in the market. You could run your whole house with a generator.

On the other hand, you will find small inverters generators to run a particular tool like charging laptop, mobile, etc. Even you could run your central air conditioner with the portable generator!

So, it is important to know the right size of the generator for a particular task. Here, in this article, I’ve elaborately discussed what size generator to run the air conditioner at your Home and RV or tailgating. 

Without further ado, let’s get started. 

What Size Generator to Run Air Conditioner

What Size Generator to Run Air Conditioner?

You can even run your AC with a 2000-watt portable generator. But to understand the perfect size of the generator, you should have sound knowledge of the basics of the generator and air conditioner. You must count the wattage of both of the appliances. Otherwise, you will regret it.

For your convenience, here is a step-by-step guide to selecting the right generator for your air conditioner. 

Select The Right Types Of Generator 

First thing first. You have to choose the type of generator first. There are different types of generators are available in the market. But all the generators are based on the two basic types. They are: 

  1. Portable generator 
  2. Stationary/standby generator  

Portable generators are less expensive than standby generators. They are also more popular. Actually, both of them have drawbacks. 

The Convenience Of Standby Generator 

If you are not a technical person or don’t have the time to maintain the tools, a standby generator could be the right choice for you. You don’t need to take special care of your standby generator. They will automatically start when the electricity goes away. 

You can run your standby generator for a long time continuously. If you are living where natural gas is available, a standby generator could be the best choice for you. You can run it for two days or three days continuously without any hassle. 

Most importantly, a standby generator is not only for the air conditioner, it can run your whole house smoothly. 

Other fuel types of standby generators are also available. Yes, they are convenient also. 

Drawbacks Of Standby Generator 

the standby generator is expensive. Though you don’t need to take regular care, it will cost extra money in any maintenance. Because you must hire a licensed electrician to fix the problem. But the standard generator doesn’t get fault easily. 

The convenience of the portable generator 

A portable generator is less expensive than a standby generator. since it is portable, you can move the generator everywhere you want. Like, you want to go camping or tailgating, your portable generator could be the best companion. 

A standard generator is easy to maintain. You don’t need any professionals to handle it. Only basic maintenance is enough for a portable generator.  

Related: Best Generator for 15000-BTU Air Conditioner

Drawbacks Of The Portable Generator

A portable generator has some limitations. You cannot run a whole farmhouse or large home with a portable generator at a time. Luckily 15000-watt portable generators are available in the market. But they are heavy indeed. Anyway, you can move them since they come with the wheel. 

generator to run AC

What Does Mean By Generator Size? 

Well, this is a mysterious question indeed. Some people think generator size means the weight, length, and height of the generator. Which is a completely wrong concept indeed. 

Generator size is measured by Watt (W) or kilowatt (KW) usually. You will find the power of the body of your generator. If you don’t find it on the body or manual, then you will surely get the volts and ampere of the generator. 

It is easy to know the watt of a generator just by multiplying the Amp and volts. 

The formula is, 

Power (watt)= Volt (V) * Ampere (A)

It is important to know the generator size to safeguard your home appliances. A low-capacity generator will damage the appliances like air conditioners. 

How Can I Select The Right Sized Generator For My Air Conditioner? 

Note Down Your Requirement 

It is important to know the requirement. Actually, you will not buy multiple generators for multiple devices unless you have a lot of appliances to run at a time. 

Say, you must run your basic appliances like the refrigerator, air conditioner, furnace in the winter, washing machine and something like that. 

Also, you can buy a generator for your air conditioner only. It depends on your situation actually. 

Calculate The Size Of Generator 

Now, make a summation of the total watt of your appliances. Say, you need 5500 watts at a time to run your basic home appliances. So, you need at least 10% more powered portable generators. 

That means you need at least (5500 + 550)= 6050-watt generator to run your home appliances. 

If you want to run only your air conditioner, then the calculation is the same. Consider the starting watt of your air conditioner and buy a generator with more peak watt than the starting power of the air conditioner. 

Our Top Pick
WEN 56475 4750-Watt Portable Generator with Electric Start and Wheel Kit

WEN 56475 4750-Watt Portable Generator with Electric Start and Wheel Kit

  • Weight: 112.5 Pounds
  • 4,750 surge watt and 3,750 rated watt
  • CARB and EPA III Compatible 
  • Electric start
  • Low-oil shutdown
  • Automatic voltage regulator

What is Average Air Conditioner Wattage?

Another point you should consider. You may find the power of your air conditioner BTU (British Thermal Unit) rather than in watt. In some cases, the air conditioner comes in Ton. It is important to know the actual power consumption for AC. You could run your window AC even with a 2000-watt generator.

Here is a chart for you to understand the range of your air conditioner in watts. 

5000 BTU AC 415 W – 625 W
6000 BTU AC 500 W – 750 W
8000 BTU AC 665 W – 1000 W
10000 BTU AC 830 W – 1250 W
12000 BTU AC 1000 W – 1500 W
15000 BTU AC 1250 W – 1875 W
18000 BTU AC 1500 W – 2250 W

Final Thoughts

I hope you have understood the basic calculation. It is important indeed to know the peak watt of your generator and the starting watt of your air conditioner. 

These days, a portable air conditioner is powerful enough to run a small house. You could run multiple window AC with even a 7500-watt portable generator. It is incredible indeed. 

Don’t make the calculation complex. If you are living in an Off-grid farmhouse, you could go for a standby generator. For short-term power outages, a portable generator is enough indeed. 


Rayan is an engineer, lives in a farmhouse. He has a passion for electronics and alternative energy. He loves to share his thoughts with other people. That is why he started the blog.

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