Among different kinds of wrenches, open end wrench is most commonly used. Open End Wrench sizes are written either in standard or metric. We will discuss the sizes of Open End Wrench in this post. The size of the wrench is same for all kinds of sockets like 2-socket, 4-socket or 6-socket wrench. Getting the perfect sized wrench is mandatory to work comfortably. See our guide below to understand the open end wrench sizes. Usually, Nut/Bolt diameter is written on it. So, you can take a look and compare that with the table above. You will then find out which open end wrench you need or you can buy a complete open end wrench set which will fulfill all your wrench requirements. If you are still confused about which wrench size you need, you can get relief from your confusing by buying an adjustable wrench. An adjustable wrench is the one which jaw can be adjusted to fit a range of nuts/bolts.