# Big-tree measurer > 24 inches across. 24 inches across at breast height, with no total yet. Blue Whale Trees, a native tree nursery in the United States. Web version: https://bluewhaletrees.com/tools/big-tree/?by=diameter&trunk=24 Try [the handbook's example, a white oak 200 inches around](https://bluewhaletrees.com/tools/big-tree/index.html.md?by=circumference&trunk=200&height=90&spread=100&spread2=80&species=white-oak), [a black gum 42 inches across](https://bluewhaletrees.com/tools/big-tree/index.html.md?by=diameter&trunk=42&height=78&spread=60&spread2=50&species=black-gum) or [a bald cypress 180 inches around](https://bluewhaletrees.com/tools/big-tree/index.html.md?by=circumference&trunk=180&height=100&spread=45&spread2=40&species=bald-cypress). Champion-tree registers rank big trees by one sum: inches around the trunk, plus feet of height, plus a quarter of the crown's average spread. Enter the trunk's circumference at 4.5 feet or its diameter, the height, the widest crown spread and the spread at right angles to it. The measurer gives the diameter at breast height, the three parts of the score with the total points, and where to nominate a tree that might rank. Choose a tree or shrub we grow, and the measurer adds its page and reads the score against the species' national champion, as a percentage of its points. One of the 45 common natives we do not grow can be chosen as well, and the measurer then reads the score against its champion and the height its sources give. Every rule is shown with its source, beginning with American Forests' handbook for measuring champion trees. Without JavaScript the inputs cannot be changed here: the score shown is for the figures in the address, or the measurer's own example. These are its rules. American Forests' Champion Trees Measuring Guidelines Handbook scores a tree as "Trunk Circumference (inches) + Height (feet) + 1/4 Average Crown Spread (feet) = Total Points". The National Champion Tree Program, run by the University of Tennessee, Knoxville since 2024, uses the same sum. The diameter at breast height is the circumference divided by pi, 3.1416, and a diameter times pi gives the inches around. The average crown spread is the mean of the widest spread and the widest spread at right angles to it, and a quarter of it counts. The total is rounded to the nearest point, as the 2024 national register prints most of its trees. Under 100 points, two trees within 3 points of each other are co-champions, and from 100 points, trees within 3 percent of the larger tree's total. The tape goes around the trunk 4.5 feet above the ground, and on a slope 4.5 feet above the middle of the slope. On a leaning trunk it goes at right angles to the lean. Where a burl or a limb swells the trunk at 4.5 feet, the narrowest point between there and the ground is measured. Where one tree forks below 4.5 feet, the national program takes the narrowest waist below the fork, or the functional circumference if that is smaller. The functional circumference is the square root of the sum of each stem's circumference squared. The height runs from the highest twig straight down to the ground at mid-slope, best read by the sine method with a laser rangefinder. The measurer refuses a trunk over 1,200 inches around, a height over 400 feet or a crown spread over 300 feet. With a species chosen, the measurer reads the points against the national champion of that species on the 2024 National Register of Champion Trees, as a percentage of the champion's points, and says when the register names no champion for a species on the program's eligible list. The national program and each state's big-tree program take nominations on forms of their own. The points compare trees of one species and say nothing about a tree's age. ## The tree's points 24 inches across Register formula **Not yet** points: the total needs the height, the widest crown spread and the spread at right angles **24 inches** diameter at breast height, from 75.4 inches around: 75.4 points The total needs the height, the widest crown spread and the spread at right angles. How old might it be? The [tree age calculator](https://bluewhaletrees.com/tools/tree-age/index.html.md?by=diameter&trunk=24) reads the same trunk. To nominate a tree, the [National Champion Tree Program](https://nationalchampiontree.org/eligibility-guidelines/), run by the University of Tennessee, Knoxville since 2024, takes nominations for the national register. It asks for six photographs and ranks only the species on its [eligible list](https://nationalchampiontree.org/current-eligible-species/). Each state keeps its own big-tree program with its own form, such as [New York's Big Tree Register](https://dec.ny.gov/nature/animals-fish-plants/plants/big-tree-register) and [North Carolina's Champion Tree Program](https://www.ncagr.gov/divisions/nc-forest-service/urban/champion-trees). The national program [lists them all](https://nationalchampiontree.org/state-programs/). - **Where the tape goes**: American Forests' handbook wraps it "at 4.5 feet above mid-slope of the tree's base". On a slope, the 4.5 feet start halfway between where the trunk meets the ground uphill and where it meets it downhill. - **A leaning trunk**: the handbook goes 4.5 feet up along the trunk's axis from mid-slope and wraps the tape "at 90 degrees to the axis of the lean, instead of parallel to the ground." - **A swelling**: below a burl or a low limb at 4.5 feet, the handbook takes "the smallest circumference between 4.5 feet and the ground." - **A fork below 4.5 feet**: the National Champion Tree Program takes the narrowest waist below the split, or the functional circumference if that is smaller. Square each stem's circumference, add the squares and take the square root. - **The height**: the national program measures "from the highest point on the tree straight down to the ground", not along the trunk. The handbook prefers the sine method with a laser rangefinder, as [the height article](https://bluewhaletrees.com/articles/tangent-vs-sine-tree-height/index.html.md) explains. - **The crown**: the handbook measures the widest spread from branch tip to branch tip over the ground, then the widest at right angles to it. Each is a level distance: the handbook defines crown spread as "the horizontal separation of two points on opposite sides of the crown". It adds that "the widest spread does not have to go through the trunk." ### How this was worked out: 3 rules and their sources - **The score**: American Forests' handbook gives the formula as "Trunk Circumference (inches) + Height (feet) + 1/4 Average Crown Spread (feet) = Total Points". The National Champion Tree Program uses the same sum. - **Inches around from a diameter**: the handbook finds the diameter by "dividing CBH by the constant pi", the circumference at breast height, so a diameter times pi gives the inches the formula counts. 24 × 3.1416 = 75.4 inches around. - **The limits**: the measurer takes a trunk of up to 1,200 inches around, a height of up to 400 feet and a crown spread of up to 300 feet. Each sits above the largest on the 2024 national register: a giant sequoia 1,026.6 inches around, a coast redwood 321 feet tall and a live oak spreading 161 feet. The points are a sum for comparing trees of one species, not a measure of a tree's age or worth. Size is a poor clock, as [How old is that tree, really?](https://bluewhaletrees.com/articles/how-old-is-that-tree/index.html.md) explains. [Why almost every tree height you read is too tall](https://bluewhaletrees.com/articles/tangent-vs-sine-tree-height/index.html.md) covers measuring height honestly. For a tree you plant, the [growth estimator](https://bluewhaletrees.com/tools/growth/index.html.md) shows how its height and trunk grow, and the [planting-site check](https://bluewhaletrees.com/tools/site-check/index.html.md) says whether it will thrive where it goes. ## How to measure a big tree - **Wrap the tape 4.5 feet up.** American Forests' handbook wraps it "at 4.5 feet above mid-slope of the tree's base". On a slope, the 4.5 feet start halfway between where the trunk meets the ground uphill and where it meets it downhill. - **Square it to a lean.** On a leaning trunk the handbook goes 4.5 feet up along the trunk's axis from mid-slope and wraps the tape "at 90 degrees to the axis of the lean, instead of parallel to the ground." - **Go under a swelling.** Where a burl, a knot or a low limb swells the trunk at 4.5 feet, the handbook takes "the smallest circumference between 4.5 feet and the ground." - **Measure a low fork twice.** Where one tree forks below 4.5 feet, the National Champion Tree Program takes the narrowest waist below the split and the functional circumference, and keeps the smaller. The functional circumference is the square root of the sum of each stem's circumference squared. - **Two trees grown together are two trees.** The handbook follows the pith, the center of each trunk, down to the ground: "If the pith lines at ground level are separated, we have more than one tree." Only the largest trunk is measured then. - **Read the height to the highest twig.** The national program measures height "from the highest point on the tree straight down to the ground", not along the trunk. - **Sight from under the top.** With a clinometer or a phone, the handbook takes the level distance to the spot beneath the top, since "The highest twig of a tree is often not directly over its base." A laser rangefinder and the sine method remove that error. - **Average two crown spreads.** American Forests' handbook takes the widest spread from branch tip to branch tip over the ground, then the widest spread at right angles to it, and averages the two. Each is a level distance, "the horizontal separation of two points on opposite sides of the crown", not one paced down a slope. Pace or tape each, and a quarter of the average counts. - **A worked example.** A tree 200 inches around at 4.5 feet, 90 feet tall, with crown spreads of 100 and 80 feet, scores 200 + 90 + 90 ÷ 4 = 312.5, or 313 points. Its diameter at breast height is 200 ÷ 3.1416 = 63.7 inches. - **Compare it with the champion.** The National Champion Tree Program's [2024 register](https://nationalchampiontree.org/champion-tree-registry/) names the largest tree of each eligible species with its points. With a species chosen, the measurer shows that tree's figures and your tree's points as a share of its, and whether the two would be co-champions. New York's register says to measure the circumference first and compare it with the current champion's, since the trunk gives most of the points. - **Nominate it.** The [National Champion Tree Program](https://nationalchampiontree.org/eligibility-guidelines/) takes nominations from the public, with six photographs of the tree. Each state keeps its own big-tree program with its own form, such as [New York's Big Tree Register](https://dec.ny.gov/nature/animals-fish-plants/plants/big-tree-register) and [North Carolina's Champion Tree Program](https://www.ncagr.gov/divisions/nc-forest-service/urban/champion-trees). ## Common questions ### How do you calculate DBH from circumference? Divide the circumference at 4.5 feet by pi, 3.1416, as American Forests' handbook does. A trunk 200 inches around is 63.7 inches in diameter at breast height, or DBH. ### How do you measure DBH on a tree with several trunks? The National Champion Tree Program takes the narrowest waist below a fork under 4.5 feet, or the functional circumference if that is smaller: the square root of the sum of each stem's circumference squared. North Carolina's program instead measures the larger stem at 4.5 feet. ### How big is the national champion white oak? The 2024 National Register of Champion Trees names two co-champion [white oaks](https://bluewhaletrees.com/plants/white-oak/index.html.md). The larger, in Virginia, scored 451 points when last measured in 2022: 337 inches around, 86 feet tall, with an average crown spread of 113 feet. ### How do I know if my tree is a champion? Measure its circumference first and compare it with the current champion's, as New York's register advises, since the trunk gives most of the points. The National Champion Tree Program takes nominations from the public with six photographs. ### Can DBH tell you how old a tree is? Not with precision, since the diameter and the points measure size alone, and a fast tree can be half the age of a slow one of the same size. Our [tree age calculator](https://bluewhaletrees.com/tools/tree-age/index.html.md) reads a range of ages from the diameter, the species and the site. The rules drawn, after the handbook's own diagrams: *On a slope: the tape goes 4.5 feet above the middle of the slope, halfway between where the trunk meets the ground uphill and downhill.* *A leaning trunk: 4.5 feet up along the trunk's axis from mid-slope, and the tape at right angles to the axis, not level with the ground.* *A burl, a knot or a low limb at 4.5 feet: the tape goes round the smallest circumference between 4.5 feet and the ground.* *A fork below 4.5 feet: the narrowest waist below the split, or each stem measured at 4.5 feet and combined, where that is smaller.* *Height: from the highest twig straight down to the ground, not along the trunk; the top is often not over the base.* *The crown from above: the widest spread from tip to tip, then the widest at right angles to it, both level distances, averaged; a quarter of the average counts.* The score and the measuring rules follow American Forests' [Champion Trees Measuring Guidelines Handbook](https://www.americanforests.org/wp-content/uploads/2014/12/AF-Tree-Measuring-Guidelines_LR.pdf) of 2014, by Robert Leverett and Don Bertolette. Its formula is "Trunk Circumference (inches) + Height (feet) + 1/4 Average Crown Spread (feet) = Total Points". American Forests kept the national register from 1940, and in 2024 the program [moved to the University of Tennessee, Knoxville](https://www.americanforests.org/article/the-national-champion-tree-program-honoring-a-rich-legacy-and-a-bright-future/). The National Champion Tree Program's [measuring page](https://nationalchampiontree.org/tree-measurements/) gives the same sum and names the handbook as its reference. New York's register and North Carolina's program score trees by the same formula. The sources disagree on where the tape goes. The handbook measures 4.5 feet above mid-slope, "where we judge the seed to have fallen", and notes that "the forestry profession typically goes 4.5 feet above the upslope point." On a leaning tree the handbook's own steps "go 4.5 feet up following the center axis of the trunk" and take the circumference there at 90 degrees to that axis, and North Carolina's [basic measuring guidelines](https://www.ncagr.gov/divisions/nc-forest-service/how-to-measure-champion-tree-basic/open) measure 4.5 feet along the stem of a leaning tree the same way. North Carolina differs in measuring from the uphill side, and 1.5 feet above the swell of a buttressed cypress or tupelo. Where a tree forks below 4.5 feet, North Carolina measures the larger stem at 4.5 feet. The measurer follows the national program and the handbook, since the national register's points are measured their way. For a state's own register, the state's guide comes first. The handbook's glossary finds the diameter at breast height by "dividing CBH by the constant pi", CBH being the circumference at breast height. The 2024 register lists almost every diameter that way. For the crown, its quickest method is "to take two measurements of the widest spreads at 90 degrees to one another", averaged. It adds that "the widest spread does not have to go through the trunk." The national program recommends several measurements of the spread, and North Carolina's guide takes the widest and the narrowest. The national program's page sets no rounding. Its [2024 register](https://nationalchampiontree.org/champion-tree-registry/) prints whole points, rounded to the nearest point for most of its 547 trees, and the measurer does the same. The handbook's examples round the crown's quarter down instead, and North Carolina rounds each part to the nearest whole number before adding, so a state's total can differ by a point. The national program names co-champions "within 3 points of each other" when the larger tree has under 100 points, and "within 3% of the larger tree's total points" from 100 points. New York's register sets the same band, and North Carolina names co-champions within 10 points. The handbook calls the sine method "the simplest and most direct way to measure tree height from the ground when the top and base can be seen by the infrared laser". The national program accepts estimates by the stick method from the public, and asks which method was used. The measurer's limits sit above the largest trees on the 2024 register: a giant sequoia 1,026.6 inches around, a coast redwood 321 feet tall and a live oak whose crown spreads 161 feet. The champions the measurer compares with come from the register's [downloadable measurement data](https://nationalchampiontree.org/wp-content/uploads/sites/270/2025/02/NCTP-2024-Register-downloadable-measurement-data.csv) of February 2025: 547 trees of 473 species, each with the year it was last measured, and the figures from that measuring. Where two or more trees share a title, the measurer compares with the one of most points. Which species can hold a national title comes from the program's [2025 Eligible Species List](https://nationalchampiontree.org/wp-content/uploads/sites/270/2025/02/NCTP-2025-Eligible-Species-List-WEB.xlsx), 1,289 species in its two eligible sheets. The catalog's Florida maple is the register's Acer barbatum, an older name for the same species, and is read under it. A register changes as trees are nominated, re-measured or lost, so a tree that scores near a champion is checked against the register itself before it is nominated. The points are a sum for comparing trees of one species, not a measure of a tree's age or worth. Size is a poor clock, as [How old is that tree, really?](https://bluewhaletrees.com/articles/how-old-is-that-tree/index.html.md) explains, and [Why almost every tree height you read is too tall](https://bluewhaletrees.com/articles/tangent-vs-sine-tree-height/index.html.md) covers measuring height honestly. For a tree you plant, the [growth estimator](https://bluewhaletrees.com/tools/growth/index.html.md) shows how its height and trunk grow, and the [planting-site check](https://bluewhaletrees.com/tools/site-check/index.html.md) says whether it will thrive where it goes. Questions the page leaves open can go to us through the [support page](https://bluewhaletrees.com/support/index.html.md#contact). The address carries the big-tree measurer'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), by (circumference or diameter, for how the trunk was measured), trunk (the trunk's measure in inches), height (the height in feet), spread (the crown's widest spread in feet), spread2 (the spread across it in feet), state (a state's two letters, such as OH, for its register). For example, [/tools/big-tree/?species=white-oak&by=circumference&trunk=200&height=90&spread=100&spread2=80](https://bluewhaletrees.com/tools/big-tree/index.html.md?species=white-oak&by=circumference&trunk=200&height=90&spread=100&spread2=80).