How this calculator works
Commercial leases describe parking as a ratio of spaces to rentable area, usually so many spaces per 1,000 square feet. Divide the number of spaces by the rentable area in thousands of square feet to get the ratio. The same ratio expressed per 1,000 square metres is larger because a square metre is about 10.76 square feet. The mode lets you turn the ratio around: multiply a required ratio by the area to get spaces, or divide spaces by the ratio to get the rentable area that the spaces can serve. Ratios describe supply, not demand; they do not guarantee that the spaces are in the right place or available to your tenants.
Formula
Parking ratio = parking spaces / (rentable area in sq ft / 1,000). Spaces = ratio x (rentable area in sq ft / 1,000). Rentable area in sq ft = spaces / ratio x 1,000. One square foot equals 0.09290304 square metres, so a ratio per 1,000 sq m equals the ratio per 1,000 sq ft x 10.7639.
Worked example
A building with 20,000 square feet of rentable area and 80 parking spaces has 80 / 20 = 4 spaces per 1,000 square feet. The same 20,000 square feet is 1,858.06 square metres, so the ratio is 80 / 1.85806 = 43.06 spaces per 1,000 square metres. At a required ratio of 3, 60 spaces serve 60 / 3 x 1,000 = 20,000 square feet.
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Frequently asked questions
Is the ratio based on rentable or usable area?
Most listing and leasing conventions use rentable area, because that is the number the ratio is compared against in lease negotiations. Some standards use gross leasable area for retail. Check which area the quoted ratio uses before comparing buildings.
Why do offices and warehouses differ so much?
Parking demand follows how many people arrive at once. An office with dense desks needs roughly one space per 250 to 300 square feet, which is four spaces per 1,000 square feet, while a warehouse with few workers may need one or two.
Can the answer be fractional?
Yes. Ratios and required areas are continuous, and even a spaces answer may come out fractional. In a real site plan you must build whole spaces, so round up to the next space and check the local zoning requirement.