When people need a hand tool set for their own auto repair jobs, they will notice there are two types of size measurements, Inch and Metric. Then they probably have a question, which is better, inch or metric?

Each size is different between inches and metric. Some of them are close, but they are different. Let's say you pick up two sizes of sockets from an inch and metric set, which is close to each other in size. For example, 5/16" and 8 mm, 3/8" and 10 mm, 7/16" and 11 mm, etc... Some pairs of sockets successfully loosen and tighten the same fastener without slipping, but some pairs are not interchangeable. Some sockets do not even grab the bolt a little. They turn freely around the fastener.

So, people should know which size their car uses, inch or metric. Metric is one of international system units while inch is one of imperial system units. Inch is commonly used and called standard size in the Unite States. For this reason, people might think US-made vehicles need an inch tool set, but they use both inch and metric fasteners.

How about Japanese and German vehicles? Japanese vehicles use mostly metric while German vehicles use both, plus other unusual shape of fasteners, such as Torx. So, if someone owns a Japanese vehicle, should he or she get a metric set?

In my opinion, you should have both an inch and metric set no matter where your vehicle is made. As mentioned above, most vehicles have fasteners of both units. Besides, you can use two slightly different sizes of sockets as an advantage when the head of a fastener is damaged. For example, old bolts have rust and then become smaller. The bolt that used to be loosened by a 10 mm socket will not turn but slip by the same socket, and 9 mm is too small, but 3/8" can grab the bolt tightly.

So, it is good to have both sets. If you have a tight budget, you should get a metric set. That is because metric is used more than inch size for fasteners of vehicles and has more sizes than an inch set. It means one millimeter is shorter than 1/16". That is why a tool set of metric size has more pieces than a tool set of inch size. Please remember the convenience of having both inch and metric sets. When any metric size sockets do not loosen a fastener, you can get an inch size socket individually.

I hope this article helps you choose the right tool set for your car repairs.