Tree Spacing Calculator

How this is calculated

⚠️ SPACE ON THE MATURE SPREAD, NOT ON THE SIZE IN THE POT. This is the whole brick. A tree bought at four feet across may finish at twenty-five, and the gap that looks absurd on planting day is the one that looks right in fifteen years. Trees planted at the spacing that felt comfortable at the nursery grow into each other, lose their shape on the crowded side, and the only remedies then are removal or a lifetime of corrective pruning. ⚠️ THE MATURE SPREAD IS AN INPUT AND IT COMES FROM THE PLANT, NOT FROM THIS PAGE. It varies by species, by cultivar, by rootstock and by growing conditions - the same species can finish at very different sizes on a dwarfing rootstock, in poor soil, or in deep shade. The figure is on the nursery tag or in the supplier's catalogue, and a local grower or your extension service will know how a species actually behaves in your area, which is often more useful than a catalogue range. No calculator can supply this, and one that guessed would be wrong by a factor of several. THE ARITHMETIC IS SIMPLE ONCE YOU HAVE THAT FIGURE. Two trees just touching at maturity need half of each canopy between their trunks, so the spacing is the average of the two spreads. Anything you want between them - a path, a mower's width, light to the ground - is added on top. That is why the gap is a separate input rather than folded in. TOUCHING IS NOT ALWAYS WRONG. A windbreak, a hedge or a screen is SUPPOSED to close up, and for those you plant tighter on purpose. An orchard or a specimen tree is the opposite - each one wants its full crown and the light to fill it. Decide which you are planting before you decide the spacing, because the same species belongs at very different distances in the two cases. ⚠️ ROOTS GO FURTHER THAN THE CANOPY, often well beyond it, and they are the half of the tree that argues with drains, foundations and paving. The clearance figure here is a CANOPY clearance - it keeps branches off a wall. It is not a root-safe distance, and it is not a substitute for the setback your local rules or your utility company require near services, boundaries and structures. Those are the authority; check them before digging. WHAT IS ABOVE AND BELOW MATTERS AS MUCH AS WHAT IS BESIDE. Overhead lines and underground services both have required clearances that have nothing to do with canopy width, and a tree planted under a line is a tree that will be cut badly for the rest of its life. THE COUNT ALONG A RUN ASSUMES A TREE AT EACH END. If the run is bounded by something - a fence, a wall, a neighbour - set the end trees in by half their spread and the count drops by one.

Common questions

Why space on the mature size when the tree is tiny now?

Because the tree does not stay tiny, and the spacing decision is permanent in a way the planting is not. A tree bought at four feet across may finish at twenty-five, so the gap that looks absurd on planting day is the one that looks right in fifteen years. Trees planted at the spacing that felt comfortable at the nursery grow into each other, lose their shape on the crowded side, and by the time it is obvious the only remedies are removal or a lifetime of corrective pruning. Plant for the tree you will have, and fill the gaps meanwhile with something you are happy to remove.

Where do I get the mature spread?

From the plant, not from a calculator. It is on the nursery tag or in the supplier's catalogue, and it varies by species, by cultivar, by rootstock and by conditions - the same apple on a dwarfing rootstock and on a vigorous one finish at very different sizes. A local grower or your extension service often knows how a species actually behaves in your area, which beats a catalogue range written for a whole country. This is exactly the kind of figure a calculator should ask for rather than assume, because guessing it would be wrong by a factor of several.

Why is the spacing the average of the two spreads?

Because each tree needs half of its own canopy between its trunk and the point where the two meet. Half of the first plus half of the second is the average, and that puts the canopies just touching at maturity. Anything you want between them - room to walk, room to mow, light reaching the ground - is added on top, which is why the gap is a separate input. Two trees of different sizes work the same way: a 30 ft tree beside a 10 ft one wants 20 ft between trunks.

Is touching bad?

Not always, and that is why the tool does not force a gap. A windbreak, a hedge or a screen is supposed to close up - the whole point is a continuous barrier, and for those you plant tighter than the touching distance on purpose. An orchard or a specimen tree is the opposite: each one wants its full crown, light all round it, and access to pick or prune. Decide which you are planting before you decide the spacing, because the same species belongs at genuinely different distances in the two cases.

Does the wall clearance keep the tree safe from the building?

No, and this is the most important limitation on the page. It is a CANOPY clearance - it keeps branches off the wall and gives you room to get past. Roots typically extend well beyond the canopy, and they are the half of the tree that argues with drains, foundations and paving. The distance that matters for those is set by your local rules, your utility company and sometimes your insurer, and it depends on the species, the soil - clay shrinkage is a particular issue - and the construction. Check those before digging; this figure does not substitute for them.

What about overhead lines?

Required clearances near overhead lines have nothing to do with canopy width and everything to do with your utility company's rules, which are not negotiable and are usually generous. A tree planted under a line is a tree that will be cut badly for the rest of its life - repeatedly, by someone whose job is clearance rather than shape - and the result is neither useful nor attractive. It is worth walking the site and looking up before choosing positions, and worth checking underground services in the same trip.

Why does the count assume a tree at each end?

Because that is the common case for an avenue or a row across open ground, where you want the planting to reach both ends. If the run is bounded by something - a fence, a wall, a neighbour's boundary - the end trees should be set in by half their mature spread so they are not overhanging it at maturity, and the count drops by one. The arithmetic is deliberately simple here rather than trying to guess your situation, so adjust it once you know which case you are in.

Take it further with AI

Copy this into ChatGPT or Claude with your own numbers filled in. It hands over the figures this calculator worked out, so the answer is built on real arithmetic instead of a guess.

I used the Tree Spacing Calculator at https://www.bfcbrilliance.com/tools/tree-spacing-calculator.

What I entered:
- Mature spread of the first tree (ft): ___
- Mature spread of its neighbour (ft): ___
- Gap you want between mature canopies (ft): ___
- Length of the run you are planting (ft): ___
- Clearance you want beyond the branches (ft): ___

What it calculated:
- Distance between trunks: ___
- Trees that fit along the run: ___
- Trunk distance from a wall: ___
- Ground each tree gets: ___
- Trees per acre on a square grid: ___

Use those figures as given — they are already worked out, so please don't recalculate or estimate your own. Help me turn them into a plan: what to buy or do, in what order, roughly what it should cost, and the mistakes people most often make with this job.

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