Tree Spacing Calculator

Background.

A tree spacing calculator has to answer two questions that people usually ask as one: how far apart the trees should be, and how many will therefore fit. The second is arithmetic. The first is horticulture, and it turns on a single number that has nothing to do with the size of your plot — the mature canopy spread of the species you are planting.

That is why this page starts with spread rather than with the plot. Washington State University Extension's guidance on landscape plant spacing puts the rule plainly: placement between two plants is one-half of the total spread for both of them. For two trees of the same species that resolves to a centre-to-centre distance equal to one full mature spread — each tree gives up half its crown radius to the gap, and the two canopies meet without overlapping. University of Florida/IFAS states the same principle independently: trees are spaced according to their mature canopy spread. Get that number from the nursery tag or your extension office; nothing on this page guesses it for you, because spread varies enough by cultivar, region, soil and pruning regime that a built-in species table would be wrong more often than it was right.

Once the spacing is set, the density is a division. The University of Georgia's Warnell School publishes the formula every forester and orchardist uses: trees per acre equals 43,560 divided by the in-row spacing multiplied by the between-row spacing. Penn State Extension prints the same table from the same arithmetic in its tree-planting guide, and the two agree row for row — 4 by 4 feet gives 2,723 trees per acre, 10 by 10 gives 436, 20 by 20 gives 109. This calculator reproduces both tables exactly.

The planting pattern is where most spacing tools stop short. A square grid wastes space. Stagger alternate rows by half a spacing and the rows nest closer: the row-to-row distance drops to the height of an equilateral triangle, 0.866 times the centre-to-centre distance, and the same crown separation now yields 15.47% more trees per acre. That is not an empirical rule of thumb, it is plane geometry, and the calculator derives the square root of three rather than shipping a rounded 0.866. Choose triangular for orchards, windbreaks and reforestation where density is the point; choose square or rectangular where you need to drive a mower or a sprayer down straight aisles.

The plot count then applies the pattern to your actual ground, minus a setback on all four sides so no tree is planted on a boundary line. Both row orientations are tried and the better one is reported, along with what the loser scored — on a long, narrow plot with a staggered grid the difference is real and worth seeing.

A scope limit that belongs here rather than in a footnote: this page is spacing geometry and nothing more. It does not check whether the species suits your site, how far a tree must sit from an overhead conductor or a buried service, what your municipality's street-tree ordinance requires, or where your septic field runs. Those distances are set locally, are not uniform, and are not modelled. In the United States, call 811 before you dig, and confirm clearances with your utility and your municipality before you order a single tree.

What is tree spacing calculator?

Tree spacing is the centre-to-centre distance between neighbouring trunks, and it is quoted two ways: within a row (in-row spacing) and between rows (row spacing). A planting described as 12 by 20 has trees 12 feet apart along each row and rows 20 feet apart.

Mature canopy spread is the crown diameter the tree will reach at maturity on your site. It is the number that governs spacing, and it is not the same as mature height — many upright cultivars are tall and narrow, while low spreading forms are wider than they are tall.

Three patterns cover almost all planting. A square grid uses the same distance in both directions. A rectangular grid widens the rows to leave an equipment aisle while keeping trees close within the row, which is why commercial orchards are usually rectangular. A triangular grid — also called staggered, offset, quincunx or hexagonal — shifts alternate rows by half a spacing so each tree sits at the centre of a hexagon of six equidistant neighbours. It is the densest arrangement of equal circles in a plane, which is exactly why it packs more trees at the same crown separation.

Trees per acre is the density measure foresters and orchardists trade in, and it describes an unbounded lattice: every tree gets a whole cell. A count for a specific plot is a different figure, because a real plot has edges and the trees sitting on them are counted while their cells extend past the boundary. Both numbers are correct answers to different questions, and this page reports both rather than pretending they should match.

What the calculator does not do: it does not select species, predict growth rate, schedule planting, size a planting hole, or apply any clearance rule. Spacing here is horticultural guidance about crowns, not a legal or utility distance.

How to use this calculator.

1. 01Look up the mature canopy spread of the species and cultivar you are planting. The nursery tag, a regional plant guide or your extension office will have it. If only the mature height is given and the tree is round-headed, height is a usable first estimate of spread.
2. 02Choose the planting pattern. Triangular for maximum density at a given crown separation; rectangular when equipment needs a wide aisle between rows; square when you want a simple, symmetrical grid.
3. 03Leave the spacing set from mature spread at 100% for specimen trees, where the crowns should just meet. Drop it towards 50% or below for a screen, hedge or windbreak that has to close into a solid mass. Push it above 100% if you want daylight between the crowns at maturity.
4. 04Measure the plot and enter its length and width in feet. If the area is irregular, break it into rectangles and run the calculator on each.
5. 05Set the boundary setback. This is the distance from the plot edge to the first tree centre, applied on all four sides. Twenty feet is WSU Extension's landscaping minimum for a strong-wooded shade tree beside a house; a street right-of-way, an easement or an HOA covenant will have its own figure and it governs.
6. 06Read the verdict beside the tree count. It tells you whether the crowns will merge, overlap, just touch or stay clear at maturity — which is the difference between a screen, a closed canopy and a row of specimen trees.
7. 07Before you order anything, read the layout note. It lists what this page does not check: utility clearances, ordinances, septic fields, sight lines and species suitability.

The formula.

Spacing comes first. In mature-spread mode the in-row spacing is the mature spread multiplied by your chosen percentage: 30 feet of spread at 100% gives 30 feet on centre, which is the WSU Extension C132 rule for two like plants. In direct mode you supply the distance and the mature spread is used only to judge the crowns.

Row spacing then depends on the pattern. A square grid sets it equal to the in-row spacing. A rectangular grid takes your own figure. A triangular grid derives it: three neighbouring trees form an equilateral triangle of side S, and the perpendicular distance between rows is that triangle's altitude, S times sin 60 degrees, which is S times the square root of three over two — 0.866 025 403 78. At 30 feet on centre that is 25.980 762 113 5 feet between rows. The square root of three is computed at forty significant digits, not hard-coded as 0.866.

Density is the University of Georgia formula: 43,560 square feet in an acre, divided by the cell one tree occupies. For the 30-foot triangular grid the cell is 30 times 25.980 762 113 5 equals 779.422 863 406 square feet, so the density is 43,560 divided by 779.422 863 406 equals 55.887 506 057 6 trees per acre. The same 30 feet in a square grid gives 43,560 divided by 900 equals 48.4. The ratio of the two is 1.154 700 5, exactly two over the square root of three — the 15.47% gain, produced by the arithmetic rather than asserted.

The plot count is a lattice-point count, not a cell count, which is why it adds one. Take the setback off both ends first: a 200 by 120 foot plot with a 20-foot setback leaves 160 by 80 feet to plant. Rows across the 80 feet: the floor of 80 divided by 25.980 762 plus one gives four rows. Trees along the 160 feet: the floor of 160 divided by 30 plus one gives six. Offset rows start half a spacing in, so they get the floor of 145 divided by 30 plus one, which is five. Two full rows of six and two offset rows of five make 22 trees. The other orientation, with rows running across the width, fits 21, so 22 is reported and 21 is named in the note.

Canopy cover is total crown area over gross plot area: pi times a 15-foot radius squared is 706.858 347 06 square feet per tree, times 22 trees is 15,550.88 square feet, over 24,000 square feet of plot is 64.795 348 480 3%. Read it carefully — overlapping crowns are counted twice, so at spacings below the mature spread this figure can pass 100%. It measures leaf area against plot area, not ground actually shaded.

The crown verdict classifies the unrounded ratio of spacing to mature spread, with band edges at exactly 0.5 and 1.0. Below 0.5 the crowns merge into a screen. Between 0.5 and 1.0 they interlock. At exactly 1.0 they just touch. Above 1.0 they stay clear. The classification never reads a rounded or displayed value, so a spacing that prints as 40 feet but is really 39.996 is correctly called an overlap rather than a touch.

Everything is carried at forty significant digits and rounded once, at the end, to ten decimal places. The only intermediate rounding is the floor inside the grid count, which is a physical quantisation — a half tree does not fit.

A worked example.

Frequently asked questions.

References& sources.

1. [1]Coder, K.D. (2023). "Number of Trees per Acre by Spacing Distance." University of Georgia Warnell School of Forestry & Natural Resources, Outreach Publication WSFNR-23-02C, January 2023, 6 pp. Source of the stated formula — trees per acre = 43,560 / (spacing direction 1 x spacing direction 2) — and of Table 1 (square grid) and Table 2 (rectangular), including the worked 9x9 = 538 and 12x20 = 182 examples. Retrieved 2026-07-31; open access PDF, read in full.
2. [2]Penn State Extension. "Forest Landowners Guide to Tree Planting Success." Table 2, "Spacing by trees per acre" — 4x4 = 2,723 through 12x12 = 303 — with the stated method "multiply the planned spacing (in feet) within rows by the spacing (in feet) between rows and divide that number into 43,560, the number of square feet in an acre." Used as the independent check on the University of Georgia table: the two agree on all nine overlapping rows. Retrieved 2026-07-31; open access.
3. [3]Washington State University Extension, Spokane County Master Gardener Program. C132, "Spacing of Landscape Plants", revised 2015, format updated 2024. Source of the spacing rule — "For two different plants, placement from each other is one-half of the total spread for both plants" — and of the default boundary setback, "Strong-wooded shade trees, such as oaks, should be planted no closer than 20 feet from the house." Retrieved 2026-07-31; open access PDF, read in full.
4. [4]Gilman, E.F. University of Florida / IFAS Environmental Horticulture, "Spacing", last modified 24 January 2020. Independent confirmation of the mature-spread rule: "Trees are often spaced apart according to their mature canopy spread." Retrieved 2026-07-31; open access.
5. [5]Wells, L. University of Georgia Cooperative Extension Bulletin B 1314, "Establishing a Pecan Orchard." Table 1 gives orchard tree density from the same 43,560 / (in-row x between-row) formula, including 20 x 20 ft = 109 trees per acre. Used as a corroborating check on the rectangular case rather than as a primary source — only the 20 x 20 row was read directly. Retrieved 2026-07-31; open access.
6. [6]National Institute of Standards and Technology, Handbook 133 – 2026, Appendix E, "General Tables of Units of Measurement". Units of Area: 1 acre = 43,560 square feet exactly, the constant behind every density figure on this page. Retrieved 2026-07-31; open access PDF.