Growth estimator
Estimate how tall, how large and how thick a tree will be in 10, 20 or 50 years. It works from the species or growth class, the height and trunk diameter now, and the quality of the site. The result is a poor-to-good range rather than a promise, and every assumption behind it is listed, so you can judge how far to trust the figure for your own tree.
Estimate
| Year | Poor site | Average site (yours) | Good site |
|---|---|---|---|
| Now | 3 ft 0.5 in | 3 ft 0.5 in | 3 ft 0.5 in |
| 1 | 4 ft 0.7 in | 4 ft 0.7 in | 4 ft 0.8 in |
| 5 | 6 ft 1.3 in | 8 ft 1.7 in | 9 ft 2.1 in |
| 10 | 9 ft 2.1 in | 13 ft 3 in | 16 ft 3.7 in |
| 15 | 13 ft 2.9 in | 18 ft 4.2 in | 22 ft 5.3 in |
| 20 | 16 ft 3.7 in | 22 ft 5.4 in | 28 ft 6.9 in |
Assumptions
- How sure. Growth varies widely within a species. American holly grew 6 feet in 16 years in shade and 22 feet in 10 years when tended, by the Forest Service's Silvics of North America. Read the poor-to-good range as the spread to expect, not as limits.
- Early growth of 1 ft and 0.25 in of DBH per year for a slow grower on an average site; a poor site (compacted, shallow, dry or shaded) is scaled ×0.65 and a good one (deep, moist, fertile, open-grown) ×1.3. These are nursery rules of thumb, not measurements of your tree.
- Height growth slows as the tree approaches a mature height of about 80 ft for Bur Oak (the top of its typical range in cultivation): barely at first, steeply near the top, and it stops there. Diameter growth slows less, which is why old open-grown trees keep getting fatter after they stop getting taller.
- A planted tree spends its first year or two growing roots while the top waits, and the estimate gives it the full rate from the first year, so a new planting reaches each height a year or two later than shown (How fast native trees grow).
- The crown width and the distance from a house are the figures its plant page gives for a grown tree, the ones the planting-site check uses; they do not change with the years ahead.
- Real trees vary enormously with soil, rainfall, competition, season length, seed source and whether the root flare was buried at planting. Open-grown trees on fertile ground can beat these numbers; trees in shade or compacted soil can fall far short. See How old is that tree, really?
Every figure on this page is an estimate.
Will it fit your spot? The planting-site check tests a spot against what Bur Oak needs: zone, sun, soil and room to grow.
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Why this is only an estimate
Two trees of the same species planted the same year can differ in height by a factor of two after twenty years. American holly, a slow grower, made 6 feet in 16 years under medium shade, while hollies mowed, mulched and fertilized for nine years averaged 22 feet at 10 years old, by the Forest Service's Silvics of North America. Soil depth, drainage, rainfall, growing-season length, competition, sunlight, seed source and whether the root flare was buried at planting all move the number. Read more in How old is that tree, really?, and on why published mature heights are often too tall in Why almost every tree height you read is too tall.
The model uses a typical early-life growth rate for the species' growth class, scales it for a poor, average and good site, and slows height growth a little at first and steeply near its mature height, stopping there. Diameter growth slows less than height growth, which is why old open-grown trees keep getting fatter long after they stop getting taller. Shrubs are projected by height only.
How the estimate is made
- Three growth classes. Each species takes the growth rate its plant page gives, or, for a species we do not grow, the rate its sources give, and a species with none counts as medium. The classes follow the Missouri Department of Conservation's key: 12 inches or less of height a year is slow, 12 to 24 inches medium, and 24 inches or more fast. The estimator gives a young tree 1, 1.5 or 2.75 feet a year on an average site.
- Three kinds of site. A poor site grows at 0.65 of the average rate and a good one at 1.3 times it. Poor means compacted, shallow, dry or shaded ground. Good means deep, moist, fertile and open. The result shows all three, and your choice marks one column.
- A slowdown near the top. Each year's height growth is the rate for the site times one minus the square of the height's share of the mature height. So it slows a little at first and steeply near the top, and it stops there. The mature height is the top of the height range on the species' plant page, or of the range its sources give for a species we do not grow. With no species it is 12 feet for a shrub, 30 for a small tree, 50 for a medium tree and 85 for a large one. A tree entered taller than that keeps its height.
- The trunk. The trunk adds 0.25, 0.4 or 0.6 inches of diameter a year by class on an average site, scaled for the site like the height. It slows less than the height, to 0.6 of its rate at the top, so an old tree keeps getting thicker after it stops getting taller. With no trunk entered, the estimator starts from the trunk its own rules give a tree of the height entered. Shrubs are projected by height only.
- The first years after planting. A planted tree spends its first year or two growing roots while the top waits, and the estimator gives it the full rate from the first year. Enter the height your tree had in its second or third spring, or expect a new planting to reach each height a year or two later than shown.
- Your site from a twig. On a tree past its first two years, last year's growth runs from the tip of the main stem to the first ring of bud scale scars. A slow grower makes about 8 inches a year on a poor site, 12 on an average one and 16 on a good one. A medium grower makes 12, 18 and 23 inches, and a fast one 21, 33 and 43. The column your tree matches is the site to give the estimator.
- Size when grown. The width when grown and the distance from a house are the plant page's own figures, the same ones the planting-site check uses. They do not change with the years ahead.
- A height to watch for. The year a tree passes a height comes from the same yearly figures, for each kind of site. A height above the mature height is never passed.
- How sure the figures are. They are rules of thumb, not measurements. Growth varies widely within a species, as the American holly figures above show. Read the poor-to-good range as the spread to expect, not as limits, and the figure for your site as the middle of it.
- The address carries the inputs. A link copied from the estimator opens with the same species, size, site and years. The page draws the estimate for them before any script runs, so a shared link and the page's Markdown copy show the figures themselves.
How tall a tree grows in 10, 20 and 50 years
For a tree that matures near 60 feet, planted as a 3-foot sapling, the model gives these heights in feet. The estimator above recomputes them for any species, starting size and mature height; a shrub or a small tree stops far sooner, and a slow grower on a poor site may never reach the top.
| Growth class and site | 10 years | 20 years | 50 years |
|---|---|---|---|
| Slow grower, poor site | 9 ft | 16 ft | 32 ft |
| Slow grower, average site | 13 ft | 22 ft | 43 ft |
| Slow grower, good site | 16 ft | 27 ft | 49 ft |
| Medium grower, poor site | 13 ft | 22 ft | 42 ft |
| Medium grower, average site | 18 ft | 30 ft | 52 ft |
| Medium grower, good site | 22 ft | 37 ft | 56 ft |
| Fast grower, poor site | 20 ft | 34 ft | 55 ft |
| Fast grower, average site | 28 ft | 45 ft | 59 ft |
| Fast grower, good site | 35 ft | 51 ft | 60 ft |
Common questions
How tall can a tree grow in 20 years?
For a 3-foot sapling of a tree that matures near 60 feet, our estimator gives 16 to 27 feet in 20 years for a slow grower, poor site to good. A medium grower reaches 22 to 37 feet and a fast one 34 to 51 feet.
How fast does a tree grow in a year?
The Missouri Department of Conservation calls 12 inches or less of height a year slow, 12 to 24 inches medium and 24 inches or more fast. Our estimator gives a young tree 1, 1.5 and 2.75 feet a year in those classes on an average site.
How much does a tree grow in diameter per year?
Our estimator adds 0.25 inches of trunk diameter a year to a slow grower, 0.4 inches to a medium one and 0.6 inches to a fast one on an average site. These are nursery rules of thumb, and the trunk keeps thickening after the tree stops getting taller.
Can you tell how old a tree is from its size?
Not with precision, since two trees of one species planted the same year can differ in height by a factor of two after 20 years. Our tree age estimator runs these rules backward from a trunk's diameter for a range of ages, good site to poor.
How do I measure how much my tree grew last year?
On a tree past its first two years, measure the main stem from its tip to the first ring of bud scale scars. Our estimator reads about 18 inches on a medium grower as an average site, 12 as poor and 23 as good.
The growth classes follow the Missouri Department of Conservation's growth key on its Tree Growth Information page. A slow tree has "an annual growth increment of 12 inches or less", a medium one "between 12 and 24 inches of growth per year". A fast tree has "the potential to grow 24 inches or more annually". The rate inside each class, the site factors, the slowdown, the trunk rates and the trunk read from a height are the estimator's own reading, nursery rules of thumb rather than measurements. The department rates hawthorns slow and black walnut medium. Here the plant pages decide, and they put Washington hawthorn in the medium class and black walnut in the fast one. Each species' mature height, width and distance from a house come from its plant page. How fast native trees grow gives measured growth for the species we grow, the first years after planting and the twig test. It also shows what soil, sun, weeds and deer do to a young tree. It names its sources, among them the Forest Service's Silvics of North America, whose American holly chapter gives the holly figures above. Every species we grow, with its class, its feet a year and its years to 20 feet by these rules, is in the growth rate table, A to Z.
The address carries the growth estimator's inputs, so a link opens it filled in, and Copy link on a result writes one: species (a plant's slug, the last part of its page's address, such as white-oak, or slow, medium or fast for a tree without one), size (shrub, small-tree, medium-tree or large-tree, for a tree without a species), height (the height now, in feet), dbh (the trunk diameter now, in inches), years (the years ahead), target (a height to reach, in feet), site (poor, average or good). For example, /tools/growth/?species=white-oak&height=3&years=20&site=good.