3-30-300 Rule

The 3-30-300 rule is a measurable and actionable urban green infrastructure guideline grounded in scientific evidence on the impacts of high-quality urban green spaces on human health, well-being, and climate resilience. This rule is directly linked to Target 7 of the United Nations Sustainable Development Goals, which aims for universal access to safe, inclusive, and accessible green and public spaces for all by 2030, within the framework of Target 11.^【1】 Rising urbanization rates and the fact that a large portion of the world’s population now live in cities have made urban greening practices a strategic priority in the context of health, equity, and environmental sustainability.^【2】 Within this context, the 3-30-300 rule, proposed by Cecil Konijnendijk in 2021, is defined as a set of objective criteria developed to create healthy, green, and equitable cities.

Objective and Core Approach

The primary aim of the rule is to ensure that urban forests and other green spaces permeate all aspects of life, work, and learning environments, and that the benefits derived from these spaces are experienced by the entire urban population. In this framework, the unequal distribution of urban trees and green spaces is highlighted; it is emphasized that developing only large, symbolic parks is insufficient, and that green infrastructure must be integrated into streets, neighborhoods, and residential surroundings.

Core Components of the 3-30-300 Rule (Generated by Artificial Intelligence)

Core Components

The 3-30-300 rule consists of three fundamental components designed to ensure adequate public access to nature. These components collectively address the concepts of visual greenery, residential greenery, and access to outdoor recreation. The rule aims for every individual to be able to see at least three mature trees from their home, to live in a neighborhood with at least 30% tree canopy cover, and to reside no more than 300 meters from a high-quality public green space of at least 0.5 hectares. The core components of the rule are as follows:

At Least Three Trees Visible from Every Home (3)

The first component of the rule requires that every individual can see at least three mature trees from their home. It is widely accepted that green elements in the immediate vicinity, particularly those visible from windows, contribute significantly to daily human-nature interaction. Trees visible from homes are considered a fundamental element that facilitates connection with nature amid the intensity of urban life, and this visibility aims to ensure continuity of urban green infrastructure even at the smallest scale.

Minimum 30% Tree Canopy Cover in Every Neighborhood (30)

The second component is based on the requirement that every neighborhood must have at least 30% tree canopy cover. This value is linked to the impacts of urban tree cover on microclimate, environmental comfort, and quality of life. Ensuring sufficient tree canopy at the neighborhood level seeks to prevent the concentration of urban green spaces solely in city centers or specific districts. This approach aims for the balanced distribution of urban forestry at the neighborhood level and the creation of sustainable green fabrics at the local scale. In areas where tree growth is challenging, the same percentage target may be applied to overall vegetation cover.

No More Than 300 Meters to a High-Quality Green Space (300)

The third component requires that every individual lives no more than 300 meters from the nearest high-quality public park or other green space. This distance is defined as a practical threshold enabling pedestrian access to green spaces in daily life. Parks and green spaces located within close proximity are regarded as spaces that encourage recreational use and function as integral parts of public life. This principle acknowledges that the importance of parks lies not only in their size but also in their accessibility and ease of use, and it includes linear green corridors, green boulevards, and similar public space types within its scope.

Implementation, Monitoring, and Global Adoption

The 3-30-300 rule has attracted attention from urban foresters, environmental experts, city planners, architects, policymakers, and the media. Many cities, including Malmö, Zurich, St. Petersburg (Florida), Haarlem, Saanich, and Viladecans, have formally or informally adopted the rule as part of their urban forestry or greening programs.^【3】 Additionally, international organizations such as the United Nations Economic Commission for Europe and the Nordic Council of Ministers recommend its implementation.^【4】

To monitor compliance with the rule, methods such as surveys, high-resolution land cover mapping, GIS (Geographic Information Systems) analysis, and network analysis are employed. The rule’s clear and numerical criteria enable comparisons between cities and allow for regular tracking of progress. Furthermore, its straightforward nature makes it easily understandable by local governments, decision-makers, and residents, thereby fostering awareness and support for urban greening policies.

Place Within Urban Green Infrastructure

This rule treats urban forestry not merely as an aesthetic or environmental feature, but as a fundamental component of urban life. Trees and green spaces are evaluated as part of a system extending from the residential scale to the neighborhood and citywide levels. The 3-30-300 rule is defined as a framework designed to ensure the continuity of urban green infrastructure, promote equity in access to green spaces, and enable cities to become more livable, resilient, and integrated with nature.