What Size Air Compressor Do I Need For Impact Wrench

by Joost Nusselder | Updated on:  March 12, 2022
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In order to run an impact wrench, you must have access to a power source. Though the cordless type of impact wrenches are highly portable, you won’t get much power for heavy uses from this type. Thus, you must select from the corded impact wrenches, which are generally high-power types, and the pneumatic impact wrench is one of them. What-Size-Air-Compressor-Do-I-Need-For-Impact-Wrench-1

As a matter of fact, you need an air compressor to run a pneumatic wrench. However, air compressors are available in various sizes, and their power supplies have different capacities depending on their size. Being confused in such a situation is pretty easy, and you may wonder, what size air compressor do I need for impact wrench? We’re here to answer this question. We will also show you how to choose the best air compressor for your impact wrench.

The Relation Between Air Compressor And Impact Wrench

In the first place, you need to know what they actually are. Basically, an air compressor keeps a huge amount of pressurized air inside its cylinder. And, you can use an air compressor to supply compressed air to the desired section. On the other hand, an impact wrench is a power tool that delivers sudden torque force to relax or tighten the nuts or bolts.

In the case of a pneumatic impact wrench, the impact wrench and the air compressor work at once. Here, the air compressor will actually provide high airflow through the cord or pipe, and the impact wrench will start creating torque force because of the pressure of airflow. In this way, the air compressor works as a power source for the impact wrench.

What Size Air Compressor Do You Need For Impact Wrench

You know that impact wrenches come in different sizes and require a different level of power for an excellent result. So, you need different sizes of air compressors for your different-sized impactors. Primarily, you need to focus on three things when choosing an air compressor for your impact wrench. Let’s have a look at these three primary considerations that assure you of getting a perfect air compressor.

  1. Tank Size: Generally, the tank size of an air compressor is calculated in gallons. And, it actually denotes the amount of air the air compressor can hold at a time. You need to refill the tank after using the total amount of air.
  2. CFM: CFM is Cubic Feet per Minute, and it is counted as a rating. This rating shows what volume of air the air compressor can deliver per minute.
  3. PSI: PSI is also a rating and the abbreviation of Pounds per Square Inch. This rating declares the amount of pressure of the air compressor in every square inch.

After knowing all the indicators above, it will become easier now to understand the required air compressor size for a specific impact wrench. In most cases, the PSI is the major considerable factor for using an air compressor as the power source of an impact wrench. Because a higher PSI rating ensures that the impact wrench is getting enough pressure to create torque force in the driver.


The basic mechanism here is that the more CFM you get, both the tank size and PSI rating will be higher. In the same fashion, an air compressor with higher CFM will fit in bigger impact wrenches. So, without further due, let’s identify the suitable air compressor for various impact wrenches.

For ¼ inch Impact Wrenches

¼ inch is the smallest size for an impact wrench. Therefore, you don’t need a high-powered air compressor for a ¼ inch impact wrench. Usually, a 1 to 1.5 CFM air compressor is enough for this small impact wrench. Though you can also use an air compressor with a higher CFM rating, that won’t be necessary if you don’t want to spend extra money.

For 3/8 Inch Impact Wrenches

This size variant is one step bigger than the ¼ inch impact wrench. In the same fashion, you also need higher CFM for 3/8 impact wrenches than ¼ impact wrenches. We recommend you use a 3 to 3.5 CFM air compressor for your 3/8 inch impact wrench.

Though 2.5 CFM can run a 3/8 inch impact wrench in some cases, we will tell you to avoid it. Because, you won’t get your desired performance sometimes because of low-pressure output. So, when you don’t have a serious issue with your budget, try to buy an air compressor that has around 3 CFM.

For ½ Inch Impact Wrenches

Most people are familiar with this size of an impact wrench due to its popularity. As it is the most used impact wrench, you may already know the required air compressor size for this impactor. Generally, 4 to 5 CFM air compressors will do nicely for a ½ inch impact wrench.

However, we will suggest you stick to a 5 CFM air compressor for better performance. Some people may confuse you by suggesting a 3.5 CFM, but it can create a lot of mess and slow down your job. Don’t forget that a low CFM air compressor cannot provide enough pressure sometimes.

For 1 Inch Impact Wrenches

If you are not involved with larger wrenching tasks or construction jobs, you may not be familiar with 1-inch impact wrenches. These large-sized impact wrenches are used for large bolts and nuts, which you will usually find on construction sites. So, it is needless to say that these impact wrenches require high CFM-supported air compressors.

In this case, you can use the air compressor with the largest size possible. If we limit the size, we suggest you use at least 9 to 10 CFM air compressors for your 1-inch impact wrench. Not to mention, you can also use your air compressor for a lot of purposes on construction sites. So, in that case, investing in a large air compressor is always a good decision.

Will A 3 Gallon Air Compressor Run An Impact Wrench?

Whenever we think of an air compressor style for our home, the first thing that comes to mind is a 3-gallon model. Because its compact and simple design is ideal for most home users. But, you may ask, will a 3 gallon air compressor run an impact wrench? When choosing an air compressor, this may be a serious concern for you. We are here to clarify the confusion. Let’s get to the bottom of it together.

Characteristics of A 3 gallon Air Compressor

Generally, the air compressors vary according to their sizes, and different-sized compressors are used for different jobs. To be specific, big-size air compressors are suitable for paint guns, paint sprayers, painting cars, etc. On the other hand, small-sized air compressors are mostly used for simple household activities like trimming, blowing, farming, roofing, inflation, fixing the nailing of walls, stapling, etc. And, because of its tiny size, the 3-gallon air compressor falls into the second category. That means a 3-gallon air compressor is actually a simple air compressor tool.

Being a low-powered tool, the 3-gallon air compressor perfectly fits in a home. That’s why people usually buy this inexpensive tool for their regular uses. The main specialty of this compressor tool is the capability of inflation. Amazingly, a 3-gallon air compressor can inflate tires quickly. As a result, you can complete such slight tasks using this small-sized tool without any issues at all.

However, can you use the 3-gallon air compressor for your impact wrench? Though this tool can handle various low-powered tasks, is it possible to deliver enough power to run an impact wrench? The answer is actually no. But why and how? That’s the topic of our discussion today.

Required Air Pressure For An Impact Wrench

Similar to air compressors, impact wrenches come in different sizes and styles. Besides, the required air pressure is different for different impact wrenches. For this reason, you cannot specifically talk about a single type or size.

If you take the largest size of impact wrench for testing, you will see that it will require an excessive amount of air pressure to run. As this impact wrench comes in the largest size, we don’t use it commonly in our homes. You will usually find this type of impact wrench on construction sites.

The required air pressure for the largest impact wrench is 120-150 PSI, and you need a large volume of air volume ranging from 10 to 15 CFM for generating such air pressure. You’ll be amazed to hear that you need a 40-60 gallon air compressor to work in that case, which is actually fifteen to twenty times bigger capacity than a 3-gallon air compressor.


So, let’s choose the smallest impact wrench for testing that comes with ¼ inches of size. This size refers to one-fourth of the largest impact wrench. And, the required air pressure is 90 PSI with an air volume of 2 CFM. Since this impact wrench needs comparatively low air pressure, you don’t need very powerful air compressors. Simply, an 8-gallon air compressor is enough to provide such pressure, which is a lot higher than a 3-gallon air compressor.

Why Can’t You Use A 3 Gallon Air Compressor To Run An Impact Wrench?

How does an impact wrench work? You need to provide sudden pressure to create a sudden force for loosening or tightening the nuts. Actually, the whole mechanism works after giving a high amount of force suddenly like a fast burst. So, you need a high amount of air pressure to create such a sudden force.

The more air pressure you will be able to provide, the stronger the sudden force you will get. Similarly, we’ve shown the air pressure requirements of two different types of impact wrenches. Even if we skip the highest size, the lowest size of impact wrench also needs a sudden force to start working.

Usually, an air compressor with more capability of holding air can also create a higher level of air pressure. As a result, you can consider a 3-gallon air compressor as a small air container that does not have a standard level of air pressure to run an impact wrench. Specifically, this air compressor comes with only 0.5 CFM air volume, which is not capable of running even the tiniest impact wrench.

Most often, people don’t choose even a 6-gallon air compressor as it will last only for 2 or 3 minutes when used to run the smallest impact wrench. Where people ignore an air compressor that can hamper their work, why will they choose such an air compressor that cannot generate sufficient air pressure and won’t work at all?

The general purpose of making the 3-gallon air compressor was not to create high air pressure. Mainly, it was designed for beginners and new air machine users. As this air compressor cannot take the load of an impact wrench, you should only consider buying it when you need an air machine for little projects and low-powered tools.

Wrapping Up

Now that you know how large an air compressor you need, hopefully you have a better idea of what size you need. Pick a size based on your impact wrench. Not to mention, a higher CFM air compressor will allow you to get a bigger tank and more gallons of air in your storage. So, always try to buy a bigger size rather than choosing one close to the edge.

I'm Joost Nusselder, the founder of Tools Doctor, content marketer, and dad. I love trying out new equipment, and together with my team I've been creating in-depth blog articles since 2016 to help loyal readers with tools & crafting tips.