Now that you have decided what system to use, you must set it up on the software. You can adjust the unit of measurement by following these steps:

1. Open a new part file.
2. In the bottom-right corner, you will find the current/default measurement system, as shown in the following screenshot:

3. Click on the current measurement system.
4. Choose from the default settings.

You can create your own measurement system by selecting Edit Document Units....This will open the following window, and is where you can select Custom Options and customize and implement your own custom units:

Note that you can change the set units at any time during the modeling process. This will convert all the units that were already set in the file. For example, let's assume that the document's length measurement was set to IPS (inch, pound, second) and a line was drawn to measure 2 inches. If we change the measurement system to MMGS (millimeter, grams, second), the length of the line will be automatically converted into 50.8 millimeters. This is because 1 inch is equal to 25.4 millimeters. 

Knowing how to deal with measurement systems is essential as our design aim will be to produce a tangible object for production or prototyping. If we don't follow the required settings from the start, our final 3D model may not have a tangible value.