Our weekly 'Explainer' returns with an overview of the term 'Floor Space Index,' courtesy of our sister site, SkyriseCities.com. You'll often see the term Floor Space Index—or, for those in the know, FSI—here on UrbanToronto, but what exactly does it mean? Read on to find out:

Each of these building blocks has the same floor area ratio, image via City of Toronto

When a development application is submitted to the planning department, it contains pertinent information regarding the proposed structure. The height, total gross floor area, and lot coverage—the percentage of the property to be occupied by buildings—are attributes that are typically specified in the application's data sheet. Figuring out the proposed density of the development is a little trickier, but can be determined by calculating the floor space index (FSI).

You can find the rest of the story on our sister site, SkyriseCities.com.