What is an Impact Wrench and What are its Benefits?

How often have you tried to loosen a stubborn, old, and rusty nut, but it doesn’t seem to budge, even a few centimeters? Sometimes the wrench slips and hits you; other times, you are left trying different types of wrenches, hoping that something will work. 

That is where an impact wrench comes in. An impact wrench is a power tool that makes it quite easy to loosen stubborn bolts and tighten loose ones. But there are many different types of impact wrenches, depending on the requirement and application. Let’s explore more about them and different applications. 

What is an Impact Wrench?

Changing tires at F1 Grand Prix using impact wrench

An impact wrench is an electrical or pneumatic power tool that makes it easier and faster to tighten or loosen bolts, fasteners, and lug nuts. More commonly used in the automotive and construction industry, these tools now come in cordless and portable forms, making it easier for DIYers and homeowners to reap their benefits.

The key feature of these power tools is their high torque, which enables users to easily loosen bolts that would otherwise be very difficult to move. Similarly, they can tighten bolts and nuts with extreme precision and speed without having to spend a lot of time and energy.

Impact wrenches can be seen in action in Grand Prix pit stops, where mechanics use these tools to change the tires of F1 cars in a matter of seconds to prevent the racer from losing their ranking.

 How Does an Impact Wrench Work?

Rusted bolt on a rusted sheet of metal

As the name suggests, the impact wrench delivers a powerful impact that is not possible using manual tools like a lug wrench or a ratchet wrench. The impact is generated with the help of a powerful motor that rotates a hammering mechanism, ultimately resulting in a high torque output.

Internally, this is done in quick succession as the hammer rotates back and forth rapidly. When the hammer moves like this, it hits the anvil and creates a large amount of torque. This torque enables users to tighten or loosen bolts easily and effortlessly.

The power with which the drive moves can be generated electronically or pneumatically. Pneumatic impact wrenches use pressurized air to move the hammer, while electrical wrenches use power from the battery(cordless) or AC power(wired).

In simple terms, the mechanism of an impact wrench is much like hitting the hammer on your ratchet or lug wrench repeatedly to move the nut or bolt in the desired direction. The only difference is that an impact wrench can do this more than a hundred times in a minute, making it highly efficient and powerful.

Key Benefits of Using an Impact Wrench

Here are some of the key benefits that an impact wrench provides.

1. High Torque Output

Impact wrenches can deliver a large amount of torque, which allows you to quickly and easily tighten or loosen even the most stubborn bolts and fasteners.

2. Speed

The rapid hammering action of an impact wrench can save a lot of time compared to using a traditional wrench or ratchet.

3. Reduced User Fatigue

The high torque output of an impact wrench means you use less physical effort to get the job done, which can help reduce fatigue, especially when working for long hours.

4. Versatility

Impact wrenches can be used for various tasks such as changing tires, working on vehicles, construction, DIY projects, etc.

5. Adjustable Torque Setting

Many impact wrenches have adjustable torque settings, allowing the user to set the amount of torque applied to a fastener. This feature can be useful for preventing over-tightening and damage to delicate components.

6. Portability

Cordless impact wrenches offer freedom of movement and can be used in areas where power outlets are unavailable. For example, users can carry cordless wrenches in their cars to change tires easily.

7. Reduced Risk of Injury

Applying too much force on a stuck nut can make your traditional wrench slip and hit you. For DIYers more susceptible to injury, such as older adults, an impact wrench provides a safer alternative to manually tightening or loosening bolts and nuts.

 Types of Impact Wrenches

 Based on Power Source

 Impact wrenches have four types based on what powers the drive operation.

1. Pneumatic Impact Wrenches

A car mechanic bolts the steel car wheel with a pneumatic wrench in a car workshop

Pneumatic impact wrenches, also known as compressed air impact wrenches, are the most traditional type of impact wrench. When impact wrenches were first developed, they featured pneumatic technology.

These impact wrenches are still used today, mainly because they don’t need a motor and are smaller in weight and size. Air-powered wrenches can weigh as little as 4 lbs, but there’s also an added expense. Since pneumatic wrenches use compressed air as the force that drives the hammer, you also need access to a compressed air tank, air compressor unit, and air hose.

2. Corded Impact Wrenches

Blue corded impact wrench

Corded electric impact wrenches use electricity to power the drive rather than compressed air. This impact wrench is suitable for you if you use it in a place with an AC outlet nearby. Corded wrenches are also less expensive as they don’t involve the additional costs of buying an air compressor, air tank, and air hose. They are also easier to operate.

3. Cordless Impact Wrenches

Cordless impact wrench with other toolsCordless impact wrenches are the most portable and user-friendly wrenches for DIY use. Even though earlier cordless technology lacked in torque and power, cordless wrenches today are close, if not equal, to high-powered pneumatic wrenches.

Most importantly, they use rechargeable batteries, making it really easy to carry them in your car or take them to the project site. You can also find cordless impact wrenches with adjustable torque, making them useful for various applications.

4. Hydraulic Impact Wrenches

Regular people and DIYers will rarely need these impact wrenches. They are most commonly used in industrial applications and take more than the trunk of a car to carry. They operate by using hydraulics as a driving force.

 Based on Shape

Impact wrenches can also be classified based on their shape and trigger placement.

1. Pistol Grip Impact Wrenches

These wrenches have the general pistol shape common in other power tools, such as drills. You grip these wrenches like a pistol, and the trigger is on the grip. The socket is at the “shooting” end of the pistol.

2. Inline Impact Wrenches

Shaped like large screwdrivers, they look similar to power saws. The D-shaped or T-shaped grip at the end of the wrench has the trigger. Smaller inline impact wrenches are best suited for working in tight spaces.

3. Angle Impact Wrenches

Angle impact wrenches have their drive bent at the right angle, much like an oscillating multi-tool. The drive rotates at a 90-degree angle from the rest of the wrench, which results in a lesser amount of torque.

Things to Consider When Buying an Impact Wrench

 Consumers need to consider the following features and qualities before buying an impact wrench.

1. Drive size

The tougher the task, the bigger the drive size you need. The most common drive sizes for everyday use are ½” and ⅜.” The latter is a relatively smaller drive size, making it more suitable for tight spaces and lesser torque.

For industrial applications, the preferred drive sizes are ¾” or 1″. Even though larger drives offer more torque, they are also heavier in size and harder to handle.

2. Power source

As already discussed, an impact wrench can be powered either electrically, pneumatically, through batteries, or hydraulics. You must choose the appropriate impact wrench depending on various considerations, such as:

  •   Task difficulty
  •   Portability requirement
  •   Budget
  •   Ease of use

3. Torque

Mechanic applying torque on a lug nut to unscrew it

Torque essentially makes an impact wrench capable of doing what it does so well. It is the twisting force of the wrench, which is often measured in either Newton meters (Nm) or foot-pounds(ft-lb).

An impact wrench with a torque rating of about 300-500 ft-lbs will suffice for everyday use. Even though it is generally a good idea to buy a higher-torque product, too much torque can be a bad thing too. It is best to research the desired product and learn about its recommended applications before buying it.

 Although more expensive, many cordless impact wrenches feature variable torque settings. This makes for a versatile tool that can adapt to various applications and can be a great investment in the long run.

4. RPM

RPM stands for revolutions per minute. In an impact wrench, RPM indicates how fast the drive can rotate the hammer. It is the measure of speed and efficiency in an impact wrench. Generally speaking, anywhere between 7000-9000 RPM is good enough. Choosing an impact wrench with an RPM rating more than what you need can over-tighten and even break bolts.

5. IPM

IPM stands for impacts per minute. Also written as BPM (blows per minute), it is the measure of how many times the hammer strikes in 60 seconds. The higher the IPM, the lesser vibration you will experience. Higher IPM will also make the tightening and loosening smoother. You should go for an impact wrench having 1500-3200 IPM for comfortable and smooth operation.


1. How much torque should an impact wrench have?

An impact driver with 300-500 ft-lb torque is best suited for most DIY applications. The higher torque wrenches are preferred for industrial and heavy-duty applications.

2. What is the most common impact wrench size?

The size ½” is the most common as it is best suited for most applications. It provides enough power and precision to handle everyday tasks efficiently.


 An impact wrench is an essential part of your home tool kit. It can significantly reduce the time and effort you spend manually tightening and loosening bolts and nuts. Choose the best-suited impact wrench based on torque and drive size, and you’ll have a reliable power tool on your hands that could make your DIY projects a lot easier.