4D v11 SQL has a new feature called the Maintenance and Security Center (MSC). Among the many items available in the MSC is the ability to get a graphical representation of your structure and data files.

Once in the MSC, click the "Information Area" and then on the "Structure" tab. You will have a screen that looks something like this:



Notice that under the brightly colored representation of used to free space of your structure there is a statement that says: "The global percentage used is 81%". It looks like:



To understand what the Global Percentage is, you must first know that at minimum each record in 4D is 128 octets (What are Octets?). If you have a table with one integer field, the size of the record will be 128 octets, not 2 octets. The remaining 126 octets are not seen in the Global Percentage because it is considered occupied space.

The Global Percentage is the difference between the size of the structure, data and index files and the total of the occupied blocks in all of these files: