Parking Ratio and Parking Space Calculators

A parking ratio is the number of parking spaces for every 1,000 square feet of building area. Use the first calculator to find the parking ratio of a property, and the second to find how many parking spaces a building needs at a required ratio.

Know how many spaces you need and want to know how much land they take? Use the parking lot size calculator to turn a space count into square feet and acres.

How to calculate a parking ratio

Divide the number of parking spaces by the building area in square feet, then multiply by 1,000:

Parking ratio = (parking spaces / building area) x 1,000

1. Count the parking spaces on the property.
2. Find the building area in square feet. Use the same measure your code or lease uses, gross or rentable.
3. Divide the spaces by the area and multiply by 1,000.

For example, a 40,000 square foot office building with 120 spaces has a parking ratio of 120 / 40,000 x 1,000 = 3 spaces per 1,000 square feet. People often write this as 3:1,000 or 3/1,000.

How to calculate required parking spaces

Flip the formula. Multiply the building area by the required ratio and divide by 1,000:

Parking spaces = building area x (parking ratio / 1,000)

A 15,000 square foot building in a zone that requires 4 spaces per 1,000 square feet needs 15,000 x 4 / 1,000 = 60 spaces. Codes usually round partial spaces up, so a result of 60.2 means 61 spaces.

What is a typical parking ratio?

Parking ratios vary a lot by use and by city. The ranges below are typical figures you will often see in suburban codes and listings. They are not requirements, and your local zoning code sets the actual number.

Apartments and houses are usually regulated per unit instead of per 1,000 square feet, for example 1 or 2 spaces per unit. Downtown areas near transit often require far less parking, and some cities have dropped minimum parking requirements entirely.

What affects the parking ratio you need?

• Use of the building. A restaurant fills more spaces per square foot than a warehouse.
• Location. Suburban sites usually need more parking than downtown sites near transit.
• Local rules. Your city's zoning code sets the minimum, and sometimes a maximum. Look up your property's zoning to find the parking section of your code.

Parking also competes with the building for space on the lot. Check the lot coverage and floor area ratio limits too, since a bigger building needs more parking and more land for it. For background on stall sizes and design, see the Wikipedia article on parking spaces.

Frequently asked questions

What is a parking ratio?

A parking ratio is the number of parking spaces for every 1,000 square feet of building area. A 20,000 square foot building with 80 spaces has a parking ratio of 4 per 1,000 square feet.

How do you calculate a parking ratio?

Divide the number of parking spaces by the building area in square feet, then multiply by 1,000. For 120 spaces and 40,000 square feet, 120 divided by 40,000 is 0.003, and 0.003 times 1,000 is a ratio of 3 per 1,000 square feet.

How many parking spaces do I need?

Multiply the building area by the required ratio and divide by 1,000. A 15,000 square foot building at 4 spaces per 1,000 square feet needs 60 spaces. Your local zoning code sets the required ratio for each use.

Should I use gross or rentable square feet?

Use whatever area your zoning code or lease uses. Many zoning codes base required parking on gross floor area, while office leases and listings often quote the ratio per 1,000 rentable square feet. Using the wrong one can change the answer by 10% or more.