3/8 vs 1/2 Impact Wrench
3/8 vs 1/2 Impact Wrench
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Over the past decades, the set of tools for the builder and any other master has noticeably increased and evolved. Some tools have become indispensable assistants in everyday life. An impact wrench is one of such instruments. It is successfully used for repair and in various household situations. It will help you hang up a picture, assemble furniture, change the lock and so on. Impact wrenches can significantly speed up work where a regular screwdriver will take hours. The huge range of applications of this tool has led to the appearance of different modifications and sizes. And in this article, we will compare the two most often used impact wrench sizes – 3/8 and ½ inches.

What is Impact Wrench?

An impact wrench is a multifunctional tool that allows you to easily screw in bolts and screws, disassemble various structures, drill holes and perform various installation work. The standard device is equipped with a motor and electronic control system. But you can complete the power tool with additional nozzles. Let us find out what types of impact wrenches exist, how they differ and what sizes are the most appropriate to have in your toolkit.

Types of Impact Wrenches

These tools can be of several types, first of all, they are divided according to the type of power source.

  • Rechargeable impact wrenches. They are convenient for their mobility and the absence of constantly interfering cords. They usually have a drilling function, which most network instruments lack. This tool is very convenient for various renovating and finishing works. The battery capacity can provide up to several hours of intermittent operation. Moreover, these models are very lightweight.
  • Network impact wrenches. These are ideal for serial use in construction and assembly work. They have a constant power supply, which usually exceeds the corresponding parameter of battery devices. These impact wrenches are connected directly to the mains. Their main advantage is that they will work as long as you need without recharging.

There are also models with a combined power supply. Such impact wrenches can work both from the accumulator, and from the mains. Cordless impact wrenches are more convenient for occasional use at home.

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Sizes of Impact Wrench

These tools come in a number of sizes. It is important to mention that by size you should understand the size of the instrument’s anvil. It is a driveshaft where you insert sockets. On the market, you can find four basic sizes of an impact wrench socket – ¼ – inch, 3/8 –inch, 1/2 –inch, ¾ -inch and a full 1-inch. If you do not have much experience with this tool, it may be difficult to determine what size will be the most appropriate for you.  And to provide you with more understanding about sizes, we will compare the most popular variants – 3/8-inch and ½-inch impact wrenches.

Comparison of 3/8 and ½-inch Impact Wrenches

Earlier in the article, we have already explained what an impact wrench is used for. Let us have a close look at the 3/8 and ½ sizes of this tool. You now understand that this parameter indicates the driveshaft diameter. So, naturally, you can immediately figure out that 3/8 modification is a smaller version, and logically, is better for more precise tasks and better maneuvering.

But it is not the only difference between them. These two sizes have different functionality. The smaller size is more convenient to access fasteners in tighter spots where ½ driver will fail to reach. If you need to tighten or loosen a 10mm bolt or even smaller parts, give your preference to a 3/8 impact wrench. It will allow you to work with extra delicate performance and will bring better results.

The ½ driveshaft is larger. It is considered a universal size that will cope with a wider range of tasks compared to a smaller size. In other words, this driver dimension will be able to provide an ideal balance of precision and power. Sometimes, when you wrongly apply the 3/8 impact wrench for bigger nuts or bolts and apply extra force, you may easily damage both the threaded part and the tool. And you can easily avoid such a situation with the ½ impact wrench.

So from the power point of view, the ½ wrench size is a better option as it provides more working potential. So this variant is more suitable for heavy-duty tasks that require extra power. If you want to understand the ½ impact wrench power in figures, then it can be expressed in a torque wrench starting from 20 pound-foot yield and up to 150 pound-foot yield.  These figures prove such a device is safe for more difficult works.

The 3/8 impact wrench is not so powerful, ranging between 10 pound-foot yield and 90 pound-foot yield. However, you should not treat these parameters only as a drawback. The smaller size will come in handy when you need small projects with the main focus on precision.

You may be puzzled about how to choose the right tool. And the answer is easy – you should always link your choice to the projects you are mainly involved in. The main guideline is to select the ½ impact wrench for hefty projects where you will surely need extra power while prioritizing the 3/8 option for more delicate jobs.

To sum up the above, here is a list of main differences:

  • The 1/2 impact wrench has a wider driveshaft than the 3/8 impact wrench;
  • The 1/2 impact wrench will allow you two work with almost double power compared to its smaller counterpart;
  • The 3/8 impact wrench allows to achieve higher precision than the 1/2 impact wrench and is recommended for delicate tasks;
  • The 1/2 impact wrench is more universal and will enable you to apply for a wider range of tasks than the 3/8 impact wrench.

The Main Benefits of Impact Wrenches

Many customers want to know why impact models of wrenches are in better demand compared to the impactless model.

  • More powerful torque. Impact models are designed to apply much less effort when operating the tool, no extra pressure is needed. For many models, the average torque parameter is 80 N/m.
  • Impact models can easily cope with both self-tapping screws and nuts, while impactless models are not good for nuts processing. The device works in the standard mode, but with the appearance of the resistance and complicated movement of the nut along its thread happens, the wrench will automatically switch to the impact mode.
  • Impact mode works without excessive force, and it allows you to avoid damaging the caps. The tool has enough strength for the reverse movement. You will find it very helpful to unscrew the parts that need replacement over time;
  • The ease of use also does not cause excessive load on the user’s hand and wrist.

The only drawback of an impact wrench is the reduction in the tightening speed during impact mode. The degree of twisting must be additionally controlled since there is no limiting feature. Another shortcoming is an increased noise level when you activate the highest speed.

How to Choose an Impact Wrench?

It is important to evaluate the tool from a technical point of view. There are several important characteristics to study:

  • Power. It is the main parameter that indicates the performance of the tool. Speaking about impact wrenches working from the mains, there is a direct dependence on motor power and energy consumption. In rechargeable models, battery voltage plays a major role. The larger it is, the more powerful the device is.
  • Maximum torque. It is the speed of the working element of the tool. For household models, it is 10-30 N/m, but professional ones require more power – up to 100 N/m. It’s great if the torque in the screwdriver can be adjusted. It will enable you to control the strength in each case.
  • Rotation speed. The performance of the instrument largely depends on this parameter. If you are looking for a tool for simple tasks, 450-550 rpm is sufficient. If you plan to use an impact wrench also a driller, you should opt for models with 1000 rpm. The higher the torque, the more difficult tasks the tool will be able to complete. Powerful models easily cope with screws of a larger diameter and will allow screwing fasteners into a denser material.
  • Weight. This characteristic is also important as it is much easier to work with lightweight models.  But a very small weight is a sign of the household class of devices. And it has a small capacity of the motor and battery. Therefore, it is unlikely that it will be very powerful, you should think about it before buying.
  • Additional functions (backlight, spindle lock, reverse).

Some manufacturers provide a convenient case for the impact wrench, where you can store various spare parts and conveniently transport the tool.

Final Thoughts

An impact wrench is a must-have tool for minor repairs, fastening parts, and for drilling particularly durable surfaces. Many professionals appreciate the lightness and compactness of this tool.  It does not damage the threaded parts even at a high rotation speed. Manufacturers and stores offer a wide range of products that allows you to choose this tool at the most attractive price. You just need to correctly decide on the size of the impact wrench. If you are mainly focused on the tasks that require high precision, 3/8 –inch impact wrench will come in handy for you. ½ -inch tools are more powerful and universal and will allow you to perform a wider scope of tasks. An ideal approach is to purchase both options to be able to cope with minor household repairs and active use in the workshop equally well.


I’m a Matthew Johnson, and I’m a motor mechanic. I like my profession and every day I use many tools, but a torque wrench is most useful of them. I’m going to write about my experience of using different torque wrenches and share with you.

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