Load Factor Calculator (Rentable vs Usable Area)

How it works

Load factor = rentable area ÷ usable area · add-on factor = load factor − 1 · rentable area = usable area × load factor · effective rent per usable unit = rent per rentable unit × load factor

Office and retail rents are charged on rentable area, which is your usable space plus a pro-rata share of lobbies, corridors, restrooms and other common areas. The load factor (also called the add-on or loss factor) is the ratio between the two and is defined by BOMA measurement standards. Two spaces with the same quoted rent can cost very different amounts per usable square foot, so compare offers on effective rent per usable area; typical office load factors run about 1.10–1.20.

Worked example

A suite with 4,000 sq ft of usable space billed as 4,600 rentable sq ft has a load factor of 4,600 ÷ 4,000 = 1.150, an add-on factor of 15.00%, so you pay for 600 sq ft of common area. At 30.00 per rentable sq ft the rent is 138,000 a year (11,500.00 a month), or 34.50 per usable sq ft.

Sources: BOMA International — Office Standard Methods of Measurement · Cresa — Understanding how square footage is calculated in your lease

Frequently asked questions