What Size Air Compressor Do I Need for an Impact Wrench?

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What size air compressor do I need for an Impact wrench, you ask? Well, although air compressors come in different sizes, the size doesn’t usually determine the compressor’s ability to power your impact wrench. In this guide, we will show you how to calculate the air requirements of your impact wrench in order to identify the right air compressor. 

What Size Air Compressor Do I Need for an Impact Wrench?

The size of the air compressor you need for an impact wrench typically depends on the size of the impact wrench. The average size air compressor you need is a 4-5 CFM @90 PSI for a ½” impact wrench.

For instance, an impact wrench with a 1″ drive will need a 10 CFM @90 PSI, a ½” drive will need a 4 CFM @90 PSI, and ⅜” will need a 3 CFM @90 PSI. 

Most impact wrenches have the ½” drive that you will most likely be looking at about 4 to 5 CFM @90 PSI.

However, there are some other factors that will determine the size of the air compressor you’ll need. These include the type of project, type of impact wrench, the power source, the amount of space you have, and where you will be using it. 

Impact wrench placed on the cement ground

How to Calculate Air Compressor Tank Size and Impact Wrench Air Requirements

There are two other very important determinants of your air compressor’s size. These include: 

  • Impact wrench air requirements 
  • Air compressor tank size

How to Calculate the Amount of Airflow Your Impact Wrench Needs

Airflow is measured in Cubic Feet per Minute (CFM). Generally, the CFM of the air compressor should meet the minimum CFM rating of your impact wrench. For this reason, CFM is usually written in comparison with the amount of pressure (PSI) needed to power an impact wrench. Mostly, that would be CFM @90 PSI. 

Since the recommended CFM of the impact wrench is set by the manufacturer, we only need to calculate the minimum CFM rating of the air compressor. To do this, you multiply the impact wrench’s CFM by 1.5. 

For example, if your impact wrench has 4CFM, the Air Compressor CFM = 1.5 x 4CFM which equals at least 6CFM of airflow from the compressor. 

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How to Calculate the Size of Air Compressor Tank Needed

Now that you know how much CFM the air compressor needs to produce in order to power your impact wrench, it’s time to determine the size of the tank that can support that airflow.

Air compressor tanks can go up to more than 60 gallons. The bigger the tank, the longer the compressor will power the impact wrench before having to produce more compressed air. Since the impact wrench won’t require a continuous flow of air like sanders or power tools such as grinders, you’ll probably be looking at a smaller tank. 

In order to find the minimum tank size, simply multiply your impact wrench recommended CP by 6. For instance, going with our previous example, if you have an impact wrench with 4CFM, the size should be:

Impact wrench with good size air compressor for wood DIY project

4CFM x 6 = at least 24- liter air compressor tank.  This is simply an estimation and we recommend that you go with a slightly bigger tank to be on the safe side.

Other Factors to Determine the Size Air Compressor You Need

There is no one-size-fits-all air compressor for every impact wrench. Below are other factors that will help you determine which air compressor is good for your impact wrench. 

Type of Project 

The type of project you are doing will no doubt determine the size of the air compressor to power the impact wrench. High-torque tasks like large construction projects, car repair or assembly projects will need a stronger air compressor such as the California Air Tools 8010 compressor.

Simple tasks like regular maintenance around the home or DIY projects will do with a smaller air compressor.

Size of Impact Wrench  

Depending on the size of the impact wrench you have, the size of the compressor will also vary. 

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That means a 1-inch drive will need an air compressor with a bigger tank and more airflow compared to a 1/2 -inch and ¼ – inch drive. 

Amount of Space

If you are not doing projects that require high-torque impact wrenches, you might want to consider the amount of storage space you have. In this case, if you have limited space, you might want to go with something smaller like a pancake air compressor. 

On the other hand, if you have plenty of space and need something with a bigger tank, you can go with a bigger compressor. However, keep in mind that size doesn’t always determine the air output of a compressor. For instance, you might get a compact air compressor with higher air output than a larger air compressor.  

Impact wrench on a wooden pallet

Your Workplace

As insignificant as this might seem, the place you will be working from might determine the size of the air compressor you need. For instance, if you only work in one place like a garage, a big air compressor will be fine. 

However, if you move from one place to another, a smaller and lighter air compressor that’s easy to move could be better. Additionally, there are other stationary workplaces that will naturally determine whether you need a big or small air compressor. 

Is the Size of the Air Compressor Important? 

Some manufacturers are now focusing on producing air compressors that are small and lightweight without compromising on power. On the other hand, most manufacturers still measure a compressor’s power by its size.

For that reason, it is difficult to determine an air compressor’s power just by looking at its size. However, you can still judge if a compressor is powerful enough by looking at these four things: 

  • Power rating in Horsepower (HP)
  • CFM – Amount of airflow from the air compressor 
  • Pounds per Square Inch (PSI) – Pressure of airflow 
  • Tank size in liters

This information is usually indicated on the user manual or on a sticker on the air compressor. 

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While the size of the air compressor needed to power a given impact wrench is still important, there are other factors that will determine if the compressor is a good fit for you. These include horsepower, CFM, and PSI. So it is important that you keep these things in mind while shopping around for an air compressor. 

An expert at home repair, remodel, and DIY projects for nearly 40 years. His first experience came in completely restoring an antique home. Completely redone from the inside out, and restored to its original form, the home is a featured design by renowned Southern California Architect Cliff May, considered to be the father of the California Ranch Home. Now Dennis spends his time on fine woodworking projects and tool comparisons.