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Root Protection Area  Calculator Tool

Welcome to our BS5837:2012 Root Protection Area (RPA) Calculator—a valuable tool designed to facilitate architects, landowners, developers, and consultants in understanding the potential rooting area of trees on their land. 

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Please note this tool is a design tool - please consult an arboricultural expert (like All Silva!) to assess soil conditions, local structures, site levels, species, tree age and confirmed RPA calculations - all of which impact the use of Root Protection Areas. 

Using the Calculator:

  1. Measure the tree - method below

  2. Enter measurements into the calculator

  3. Use the RPA Radius to understand site constraints

Single Stem Tree.png

Single stem

Measure tree at 1.5m

Multi-stem Tree.png

Multi-stem

Measure tree at 1.5m

Tree RPA diagram2.png

RPA Radius

The calculation output is the distance from the stem to the edge of the Root Protection Area

Single-stem Trees

  1. Enter stem diameter and click Calculate

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Multi-stem Trees

  1. Type number of stems measured - click anywhere

  2. Input stem measurements in cm - click Calculate

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Details & Help

Bonzai Tree

By utilizing this calculator, you gain valuable insights into the spatial extent of tree roots, enabling informed decision-making and effective planning. Whether you're navigating construction projects, landscaping endeavours, or property development, our BS5837:2012 RPA Calculator empowers you to enhance design precision and environmental stewardship. Explore the tool today and unlock the key to sustainable and well-informed land development.

  • A copy of the British Standard 5837:2012 is (currently) available for FREE here.

  • If the tree has been measured using a standard tape measure (circumference), the figure will need to be divided by PI to create stem diameter. 

  • The calculated output is capped at 15m radius, however this should be extended if the tree is ancient or veteran.

  • Single-stem - ​RPA Calculation: The RPA is calculated based on a formula - Squareroot (mean stem diameter)2 × number of stems. This is then multiplied by 12/100 to provide the RPA radius in metres. 

  • Multi-stem - The RPA is calculated based on a formula - Square root (mean stem diameter)2 × number of stems. This is then multiplied by 12/100 to provide the RPA radius in metres. 

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This is a design tool, and should be used in conjunction with arboricultural expertise to assess ground conditions, biomechanics, tree root morphology, species etc. 

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All Silva take no responsibility for any issues arising from inaccuracies produced in conjunction with this tool.

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