What size of air compressor do I need to work on cars?


Air compressors have various uses. It’s important in many engineering sectors. Air compressors are very effective in automotive engineering also. It can help you in your garage or your auto repair shop. But people are confused about the real concept of the air compressor. They did not understand the size of the compressor for the garage. Here is a common question “What size air compressor do I need to work on cars?”. In my article, I am going to tell you about the size of the air compressor for your garage.

Air compressors use diversified air tools. Selecting an air compressor is not an easy decision. You have to consider some factors. At first, you have to know about your air tools requirement and then match the requirement with the air compressor. I will discuss all factors elaborately. Follow the article.

Air Compressor

Air compressors are used in many industries. It is used in automotive industries also. In auto body shops and auto repair shops, the air compressor is very familiar. It helps to run air tools by using air. 

An Air compressor is a device that changes power into intense energy by storing pressurized air. To increase the pressure an air compressor pushes more and more air into the compressor’s storage tank. The compressor shuts off when the tank’s rising pressure reaches its upper limit. Then the compressor stored the compressed air in the tank for future use.

Size of air compressor that I need to work on cars

There are three factors that can help you to determine the size of the air compressor. When you are thinking about purchasing an air compressor for cars, decide first which tools you will use often. If you want to use spray paint on your car or an impact wrench for your tire, the air compressor requirements of these tools aren’t the same. So, purchase an air compressor wisely that is able to run both of your air tools.

How to Size an Air Compressor

The two-term Air pressure and CFM requirements converse often. Some air tools have higher PSI requirements and will need a lower CFM rating.

Let’s discuss how to determine your desired size-

  • Air compressors tank size

For some tools, you need only a larger tank. But most of the tools can run with a small capacity tank. Some air tools run smoothly with a small size tank like a 20 or 30-gallon. Impact wrenches, air guns, nail guns, ratchets, etc. can run with small size tanks. But if you want to run a spray painter you need a larger tank or higher capacity air compressor.

You can ask, why does a spray painter need a higher capacity air compressor? When you paint your car with a spray painter with a small tank compressor, you have to stop the work to refill the tank again. While you will refill your tank the painted area will become dry. When you start painting again the paint will not look even.

If you use a larger tank like 50 to 60 gallons you can paint the whole car in one refill. Then the paint will look even.

  • Air pressure

PSI is the unit that measures an air compressor’s air pressure. PSI stands for pounds per square inch. It measures pounds of pressure in one square inch. PSI is the measurement of how much pressure your air tools require to run. Most air tools require a minimum of 90 PSI to run smoothly.

Here the most important thing to consider is to match your air tools required PSI with your air compressor. If you will not match the air tools PSI then it will not run smoothly and sometimes it can damage your tools. Most of the air compressors from small to large sizes available on the market will offer you 90PSI pressure.

  • CFM

CFM measures air volume in cubic feet for every minute it moves. CFM stands for Cubic feet per minute. It indicates how much volume of air your air compressor can supply every minute.

Every air tool has a different CFM requirement. One tool’s requirement will not match with another one. If an air hammer CFM requirement is 4 then a tire inflator required CFM can be 2.

Remember that your air compressors CFM and air tools CFM are not similar. So, You have to multiply your air tools required CFM by 1.5 to calculate your compressor’s CFM.

Consider the following things to run air tools on cars

There are some important issues you have to take care of. If you want to keep your air compressor in good condition you should maintain some rules. These are not only applicable for your car tools but also for all other air tools you want to operate with your air compressor. 

tools to air up a tire with an air compressor

Check the capacity of the power outlet

A 120-volt power outlet is appropriate for a small-size or portable air compressor. But if you will operate a large-size air compressor with a large-size tank like a 60-gallon tank then a 240-volt power outlet will be good. a small-size air compressor with a 30-gallon tank will require almost 15-20 amperes of electricity. So, here you need to be careful about, maximum power outlets usually provide you with 20 amperes or less electricity.

Here is an expert opinion, that you should not run multiple machines with the same circuit. If you use the same circuit for multiple machines there is a risk of damaging the circuit.

Required PSI for every tool

When you will use an air tool you have to keep in mind that every air tool has a separate PSI recommendation. You should select an air compressor that will meet your air tools PSI recommendation.

If you do not use recommended settings then your air tools and air compressor will damage soon. Please don’t think about saving money here otherwise you will lose valuable machines. So be a wise man and save yourself from losing valuable things and unexpected costs also.

I told you before that every air tool has PSI recommended by the manufacturer. If you use manufacturer-recommended PSI it will increase air compressor and air tools efficiency. Because every air tool runs best in its required PSI rate.

What is PSI Pressure

You shouldn’t leave the compressor Unattended

Once you finish your work turn it off and if possible disconnect your machine from the power source. If you leave your machine unattended, accidents can take place. Air compressors and power tools can cause accidents also. So be careful about your machines.

Research to know more

When you are planning to buy a new air compressor for your power tools observe the market first. There are so many brands and so many options also. Research the market under your demand. What kind of air compressor will be good for your air tools?

Never buy an air compressor in the imagination of your power tools. If you didn’t buy any power tools then don’t buy the air compressor. Buy your air tools first and check the recommended PSI of all your tools. After that decide about the air compressor that matches your air tools PSI.

Here, I will suggest you go for the highest requirement if you have more than one air tool. Because you can set the air compressor low but it’s impossible to set it higher than its capacity.

CFM Chart

People use some regular air tools in garages or automobile shops. Here is a CFM chart for you. It will help you to understand different air tools’ requirements. If you want to be more sure then check your tools instruction manual.

Air toolCFM (Average)PSI (Average)
Paint spray4 to 890 to 100
Impact wrench3 to 10 90 to 100
Blowgun 2 to 390 to 100
Impact driver 4 to 1290 to 100
Tire Inflator2125 to 150
Air hammer490 to 100
Ratchet3 to 490 to 100
Orbital sander6 to 970 to 100
Drill470 to 90

Choose the air compressor under the air tools requirement. Go for the highest requirement, the compressor will serve your garage for a long time.

Different sizes of air compressors for the automotive service industry:

Choosing an air compressor is a challenging job if you don’t have enough knowledge. There are some regular tools we use in auto body shops and auto repair shops. I mentioned before that to select an air compressor, we should follow the air tools requirement that we want to use.

Usually, an auto body shop and auto repair shop needs 80 gallons to 240-gallon air compressors with 5 to 30HP to run necessary pneumatic tools. For the small project, you can use 20 gallons to 60-gallon air compressors to run light air tools. But with a small size tank, you have to stop several times to refill it. So, it’s better if you choose the air compressor with a large size tank.


How big of a compressor do I need to paint a car?

You can paint your car at home. It’s affordable also. But the first thing you have to decide is the proper size of the air compressor for your paint tools. But it depends on several things, such as how big your car is, full vehicle painting, or small portion painting.

Based on these operations choose your paint gun first. The following steps will help you to find out the perfect air compressor for your job-

Fit your compressor to the paint gun: If you already have a paint gun you can match the CFM and a PSI with your compressor. Spray the paint in a proper way; a professional paint gun requires 12 CFM.

Consider the Compressor tank size and CFM: when you are going to paint a car your first task is to match the CFM of the paint gun and compressor. It will be good if you use the 50% higher CFM rating compressor than your paint gun. A large size tank like 60 gallons or more will be suitable for painting a full vehicle.

Self-contained paint system: If you haven’t enough space for an air compressor you can follow the self-contained paint system with the turbine-style paint gun. But this system is more expensive than the previous one

Can I paint a car with a 20-gallon compressor?

Painting a car at home is a tremendous job if you have a good air compressor and a nice paint gun. But you have to consider some factors for uninterruptible work. First, decide the project size, do you want to paint a whole car or a small portion only? If you want to paint a small portion then tank size won’t affect you. But the whole car painting requires a large size tank like 60 gallons if you want the smooth finishing. Otherwise, with a small size tank like 20 gallons, you can paint the car but you have to stop to refill the tank so many times. The car paint will dry in the middle of the refilling and the paint won’t be even and smooth. Painting a car with a 20-gallon air compressor is possible but the outcome will not be good.


The air compressor you will select for your car or garage is dependent on some factors. You have to go through some selection of air tools you need, then you have to check their requirements. Then select the air compressor and check whether it matches your power tools required or not. Always try to go for the highest requirement. It will add more advantages to your work. Small-size air compressors only run small tools. If you are involved with any large project like painting a car, it will not support you. So, invest your money wisely. Hope my article will help you to understand the right size of air compressor you need to work on cars.

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