Open Space Ratio
When talking about the open space ratio we are referring to a term that is used in zoning laws and regulations. The open space ratio is a term used to measure open space on a developed land or zoning lot. The open space ratio is calculated in the percentage of open space in the building's square footage. For example, a housing subdivision containing 100 acres has devoted 10 acres to open space. Therefore, the open space ratio is 1/10 or 10 percent (10/100). Or an office building of 10,000 square feet with an open space ratio of 20% will have 2,000 square feet designated to remain open space.
Open Space Ratio in Residential Real Estate
The term open space ratio is a concept that applies to residential developments, and it usually refers to commonly used open space. While not necessarily a way to determine the ratio of “green” open space on lots of land proposed for residential development. The term open space ratio can refer to two types of open space:
- Allowable Areas
Allowable open space are the areas that are required common areas to be maintained and remain undeveloped for the benefit of those living or working on the lot parcel: parking lots, yard requirements, floodplains, recreational areas, stormwater management systems, etc.
- Prohibited Areas
Prohibited open space areas are privately owned sites that are not accessible for those living or working on the lot parcel and that are also available for further structural developments.
How is Open Space Ratio Calculated?
The open space ratio is a zoning law used by municipalities to be able to control the types of buildings built, their height, and their ratio of open space. It is a means for municipalities to ensure that the open space available on a developed land makes up a certain percentage of the lot developed. In most cases, that requirement is of a 20% open space ratio.
Open Space Ratio Formula:
Open Space Ratio (OSR) = Commonly-owned Open Space / Total Area Proposed for Development
So if you have 12 acres available for residential development and you have 6 acres of commonly-owned open space (ponds, recreation area, parking area, buffers, etc) you will have an open space ratio of 50%.
Popular Real Estate Terms
Right of an individual to be offered something before it is offered to others. For example, a tenant whose apartment is going to be converted to a cooperative has the first right of ...
The fire insurance term is a policy used in property insurance that ensures any damage or loss that was a result of a fire. Most affordable home insurances cover fire insurance but other ...
Mortgage for an extended time period (e.g., 25 years) Type of real estate investment trust (REIT) that gives long-term mortgages to real estate developers and contractors on new or ...
Early American frontier-style house constructed of logs. Since finished lumber was not readily available during the early frontier period of American history, homes were often fashioned out ...
Contract to act on the behalf of a principal in selling real estate. The principal agrees to pay a commission to the broker when a buyer is produced who is ready, willing, and able to meet ...
The meaning of commercial acre in the United States defines the remaining part of an acre of a newly divided land once curbs, streets, and boardwalks have been separated from the original ...
Created by law usually for the right to travel to landlocked parcel of land ...
Siding made out of aluminum, plastic derivates, or cement asbestos having ridges and valleys which is attached to the sides of buildings. ...
(1) Paved roadway constructed above lowlands such as a swamp. (2) Roadway in ancient Egypt connecting the valley temple with a pyramid. ...

Have a question or comment?
We're here to help.