How to Measure the Height of a Tree

In a secret spot in Northern California, the height of a tree named Hyperion was measured at a world-record 115.61 meters! Believe it or not, an extremely long rope was used to measure this, though there are simpler ways you can measure on your own. If exact measurements down to the centimeter aren't required, the methods below will give you a pretty accurate result. These techniques can be applied to any tall object, whether it's a telephone pole, a building, or even the legendary beanstalk—if you can see the top, you can measure it.

This method helps you measure the height of a tree without needing to do any complex calculations. All you need is a piece of paper and a measuring tape. There's no need for any math, but if you're curious about how this method works, you might want to learn a little trigonometry. The technique that involves an inclinometer and line of sight does require calculations and an understanding of why the method works, but you don't need to do that to find the height using this simple approach.

Fold the piece of paper in half to form a triangle. If the paper is rectangular (not square), you will need to trim it to make a square. Fold one corner to create a triangle with the opposite edge, then cut off the excess paper above the triangle. You now have the triangle you need.

Hold the triangle in front of one of your eyes. Keep the 90º angle steady and turn the other part of the triangle towards you. One side of the triangle should be parallel to the ground while the other is upright. You can look along the longest edge by tilting your head up.

Step back from the tree until you can align the top of the tree with the peak of the triangle. Close one eye and look along the hypotenuse of the triangle with your other eye until you can clearly see the top of the tree. Find the point where your line of sight along the hypotenuse meets the top of the tree.

Mark this point and measure the distance from there to the base of the tree. This distance is approximately the height of the tree. Add your own height to this measurement since you're viewing the tree from your eye level. And now, you have your answer!

Use this method if you only have a tape measure or ruler. You don’t need any other tools to perform this method, and you will be able to estimate the tree’s height accurately. The only thing you need to do is some multiplication and division.

• If you don't want to do the math, you can visit the internet and use a calculator to determine the tree's height, such as this one, and enter the measurements you found using the method above.

Measure your own height. Use a tape measure or ruler to measure your height while standing up straight. Measure while wearing the shoes you plan to wear when performing this method. You will need a piece of paper to write down your exact height so you don't forget it.

• The measurement you get should be in consistent units, like measuring in centimeters, not a mix of meters and centimeters. If you’re unsure how to convert between units, you can use a measuring tape (meter tape) for the measurement. Use the length of the ruler and the length of the ruler’s shadow when instructed to use it.
• If you need to sit in a wheelchair or cannot stand up straight for any reason, measure your height in any position when you go outside to measure the tree’s height.

Stand on level, sunny ground near the tree. Try to find a spot where your shadow stretches out on flat ground to get an accurate measurement. For the best results, use this method on a sunny, clear day. If it’s cloudy, it can be hard to measure the shadow accurately.

Measure the length of your shadow. Use a tape measure or ruler to measure the distance from your heel to the tip of your shadow. If you have no one to help, you can mark the end of your shadow by throwing a stone at it while you’re standing. Or better yet, place the stone at a point on the ground and adjust your position so that the tip of your shadow is aligned with the stone, then measure the distance from where you stand to the stone's location.

• Write down and label each measurement immediately after calculating it to avoid confusion.

Measure the length of the tree's shadow. Use a tape measure to determine the length of the tree's shadow from the base of the tree to the tip of the shadow. This method works best when the ground around the shadow is relatively level; if the tree is on a slope, the measurement might not be completely accurate. Perform this measurement right after measuring your own shadow because the position of the sun will cause the shadow's length to change.

• If the tree's shadow is on a slope, there may be another time of day when the shadow avoids the slope by shortening or shifting to a different direction.

Add half of the tree’s diameter to the length of the tree's shadow. Most trees grow straight, so the highest point of the tree will be at the center of the tree. To calculate the length of the tree’s shadow, you need to add half the width of the tree trunk to the measurement of the shadow. This is because the top of the tree usually casts a longer shadow than what you can measure; some tops fall behind the tree trunk, making them invisible.

• Measure the width of the tree trunk with a ruler or tape measure, then divide by two to get half the diameter of the tree. If you're unsure how to measure this, draw a square around the base of the tree and measure one side of the square.

Calculate the height of the tree using the results you’ve recorded. You’ve recorded three values: your height, your shadow’s length, and the tree’s shadow length (including half the diameter of the trunk). The shadow length of an object is proportional to its actual size. In other words, if you divide (your height) by (your shadow length), it will equal (the tree’s height) divided by (the tree’s shadow length). You can use this equation to determine the tree’s height:

• Multiply the tree’s shadow length by your height. For example, if you are 1.5 meters tall and the tree’s shadow is 30.48 meters long, multiply these two numbers: 1.5 x 30.48 = 45.72.
• Divide the result by your shadow’s length. Using the example above, if your shadow is 2.4 meters long, divide: 45.72 / 2.4 = 19.05 meters.
• If you’re not good with calculations, you can use an online calculator to determine the tree's height, such as this one.

Use this method as an alternative to the shadow method. Although less accurate, this method can be used when the shadow method isn’t feasible, like on a cloudy day. Also, if you have a tape measure, there’s no need for calculations. If not, you’ll need a ruler and do some simple multiplication.

Stand far enough away so you can see the entire tree from base to top without moving your head. To get the most accurate measurement, stand on level ground, aligned with the ground around the tree’s base, neither higher nor lower. The fewer obstructions in your view, the better.

Extend your arm and hold a pencil. You can substitute the pencil with any small, straight object like a paintbrush or a ruler. Hold the pencil in your hand and stretch your arm out so that the pencil is directly in front of you (between you and the tree).

Close one eye and adjust the pencil up or down until the pencil’s tip aligns with the top of the tree. The easiest way is to point the pencil’s tip upward. The tip will cover the top of the tree when you look at the tree “through” the pencil.

If you have a tape measure, measure the distance between your helper and the tree. Instruct them to stand still or mark their position with a stone or stick. Use the tape measure to determine the distance between the marked point and the tree's base. The distance between your friend and the tree is the tree's height.

Using this method will yield more accurate results. The previous methods are also accurate, but with a bit of calculation and specialized tools, you can get more precise results. It may sound complicated, but it’s not: all you need is a calculator that can compute "tangent," a plastic protractor, a straw, and a string to create your own inclinometer. This tool measures the angle of an object, in this case, the angle between you and the top of the tree. The sextant tool serves a similar purpose but is more advanced, utilizing a telescope or laser beam for more precise results.

• Like the Paper Method, this approach is not only more accurate but also allows you to measure any distance, rather than moving forward and backward to align the paper with the tree’s trunk.

Measure the distance to the sighting position. Stand with your back to the tree and move out to a point where the ground is level with the area around the tree’s base and from where you can clearly see the top of the tree. Walk straight ahead and use a tape measure to record the distance between you and the tree. You don’t need to stand at a predetermined distance, but typically, this method works best when you are about 1 to 1.5 times the height of the tree away from it.

Measure the angle to the tree's top. Look at the top of the tree and use an inclinometer or a sighting instrument to measure the "elevation angle" between the tree and the ground. The elevation angle is the angle formed by two straight lines—one along the ground and the other from your eyes to a specific point (in this case, the top of the tree). This forms the apex of the angle for you.

Find the tangent of the elevation angle. You can calculate the tangent of an angle using a calculator or trigonometric table. The method for finding the tangent may vary depending on the calculator you use, but generally, you just press the "TAN" key, input the angle value, and press the "equals" (=) key. If the elevation angle is 60 degrees, you just press "TAN", type "60", and hit equals.

• Click here to go to a website for calculating the tangent of an angle.
• The tangent of an angle in a right triangle is calculated by dividing the length of the adjacent side by the length of the opposite side. In this case, the opposite side is the height of the tree, and the adjacent side is the distance between you and the tree.

Multiply the distance from you to the tree by the tangent of the elevation angle. Remember, you already measured that distance at the start. Multiply this distance by the calculated tangent value. The result will give you the height of the tree from your eyes, since that's where you calculated the angle.

• If you reviewed the previous step about the tangent definition, you can see why this method works. As stated, the tangent of an angle = (height of the tree) / (distance to the tree). By multiplying both sides of the equation by the (distance to the tree), you get (tangent of an angle) x (distance to the tree) = (tree height from your eyes)!

Add your own height to the result. You now have the accurate height of the tree. Since you used an inclinometer and sighting instrument from your eyes, not from the ground, you must add your height to the result to obtain the tree's total height. You can get a more accurate result by measuring your height from your eyes instead of your head.

• If you're using a paper sighting instrument, add the distance from the point where your eyes line up with the instrument to the ground instead of your height.