Rentable square feet is the measurement used to calculate your lease payment. However, it is not the actual size of the office you’ll be renting. ”Rentable” means not only the size of the actual rooms but includes your share of the bathrooms, stairways, elevator shafts, mechanical and electrical closets in the building.
There’s a formula involved and it changes for every building. This formula is called the load factor (or loss factor) and can run anywhere from 27% to 31% or higher, depending on the building.
Although this sounds innocent enough, it is one of the most frustrating parts of finding office space.
The number you really should be concerned with is the “usable square feet” or “carpetable square feet” and you won’t know that until you see the space in person and measure it.
In summary, you’ll be paying your rent based on the higher (rentable square feet) amount but will be working in the usable square footage.