Tree Canopy Target Calculator
How many trees an area must plant to move from its current tree-canopy cover to a target — allowing for the mature canopy each tree gives and the share that will not survive.
Canopy cover is the share of the ground shaded by tree crowns seen from above.
How the tree canopy target calculator works
Canopy cover is the share of the ground shaded by tree crowns seen from above. The gap between current and target cover, times the area, is the canopy to add; divide by the crown area of a mature tree (a 6 m crown is 28 m², a 10 m crown 79 m²) and by the survival rate to get the number to plant. Trees take 15–25 years to reach mature crown size, so the target is a date, not a planting season.
Formula: trees = area × (target − current) ÷ (mature crown area × survival)
Worked examples
| Inputs | Trees to plant | Note |
|---|---|---|
| 100 ha from 15% to 30%, 8 m crowns, 70% survival | 4,264 | 4,264 trees |
| A 2 ha school from 10% to 25% with 10 m crowns | 48 | 48 trees |
| Target already met | 0 | none |
FAQFrequently asked questions
What canopy target is typical?
Many cities aim for 30–40% by 2040 or 2050 from a current 15–25%; hot, dry cities set lower targets and leafy temperate suburbs already exceed 30%. The figure that matters is the change, which is what the calculator prices.
Why allow for survival?
Street and park trees lose 20–40% in the first years to drought, damage and vandalism, and more if they are not watered while establishing. Planting only the net number guarantees a shortfall.
What crown size should I use?
The mature crown of the species mix you will plant: small street trees 5–6 m, medium 8–10 m, large park trees 12–20 m. Larger trees give far more canopy per planting hole, which is why species choice matters more than count.
Does this include trees lost meanwhile?
No — removals and natural loss of existing canopy must be replaced on top. Cities losing 1% of canopy a year need that much planting just to stand still.
Where these figures come from
- UN-Habitat — Urban Indicators Guidelines — density, green space and public space benchmarks
- World Health Organization — Urban green spaces — the 9 m² per person minimum
- ITE — Parking Generation Manual — parking demand rates by land use
- Office for National Statistics — Population estimates — the UK's national statistics agency
Last checked: September 2026. Default per-capita rates are mid-range figures from national statistical agencies and utility reports; every one is an input you should replace with the local figure.