When you want an impact wrench from Milwaukee, the chances are you may consider the Stubby ½” or the ⅜” models. What is crucial is to understand what differentiates the two and where best to use them. That is what we look at below.
Milwaukee® M12 FUEL™ Stubby Impact Wrenches (1/2″ vs 3/8″)

The Power
Looking at the two, both the ½” model and the ⅜” impact wrench have a similar power of 250 ft/lbs. Such power makes the model useful for delivering enough torque to remove rusted bolts and nuts.
We can recommend using the ⅜” for jobs that need less than 150 ft/lbs to get done. Those stubborn bolts are best removed with a ½” impact wrench because of the larger battery.
Weight and Size
The ½” model is more powerful meaning it has to pack a larger motor and battery. These two components mean there is increased weight. So, this model is heavier than the ⅜” model.
As for the dimension, the ½” model is larger because of the bigger battery and motor. This allows it to have more torque generated.
The ⅜” impact wrench is smaller, making it suitable for tight space applications generally.
Milwaukee M12 FUEL Stubby Impact Wrenches in 1/2″ 3/8″ & 1/4″ Anvils For Tight Spaces

Usability
People would find the ⅜” impact wrench more portable. This is because of its smaller size and it is generally lighter. So, you can take it to various places for different uses. Just make sure they are light applications.
The ½” model would work best for applications that need more torque. We are talking of scenarios such as rusted or stubborn bolts that need more power to get loose.
Precision and Accuracy
Sometimes precision is important when using an impact wrench. You get that with the ⅜” impact wrench. With its impressive precision, you have an easier time removing or fastening the bolts and nuts.
Its precision is generally better because lesser torque means you have more control over the tool. Also, being lightweight means you can handle similar tasks more often without fatigue.
The Design
These two impact wrenches are designed relatively the same. You can find them both have ergonomic features key to helping you use the tools for longer.
A good example is having soft grip rubber handles. Such is important for ensuring there is better grip and comfort while using impact wrenches.
The presence of LEDs is also important. This is vital to help see better when working in dark areas.
There is also the variable speed trigger that allows you to adjust the speed at which you are using the impact wrench for better control.
Here is a quick video on the ½” impact wrench application in real life

FAQs
Which is better between the two?
If you want more power, then the ½” tool has more torque to use but if you want portability and a wrench to use in tight spaces, the ⅜” impact wrench is the best.
What is the difference between the M12 and M12 Fuel systems?
The main difference is that the M12 Fuel has a brushless motor while the M12 has a brushed motor.
Are the lithium batteries in the Milwaukee impact wrench good?
These batteries are designed to give more power per charge and more battery life even with regular use.