Free calculators
Free arborist calculators
AS 4970:2025 tree protection calculations and everyday trunk measurement conversions, each with a live scaled diagram.
NRZ & TPZ Calculator
Notional Root Zone from DSH, TPZ fence and drawn works.
SRZ Calculator
Structural Root Zone radius and area from DARB.
Encroachment Zone Calculator
NRZ encroachment area and minor, moderate or major classification.
DSH / Circumference Converter
Convert between trunk diameter and circumference.
Basal Area Calculator
Trunk cross-sectional area from DSH.
Canopy Spread Calculator
Canopy (crown) area from average canopy radius.