Trees are tall. Humans, relatively speaking, are not. And we're not the most agile climbers in the animal kingdom, either. But we are crafty, and we can out-think even the most wizened redwood. But how do you do so when all you've got is a pencil, a mirror, or a smartphone? In the first installment of a new series powered by Q&A site Stack Exchange, we're taking the question to the crowd.


Photo by Two+two=4".

I'd like to install an antenna for Internet service, but it will need to clear some trees on my neighbor's property as it requires a clear line of sight to work.


I really don't trust my estimating skills enough to plunk down money on a utility pole that might be too short or too tall. And climbing the tree with a tape measure (in my neighbor's yard) is a bit intrusive and dangerous.

Other than eyeballing it, is there a clever way that I can get a reasonably accurate (within 5' or so) estimate of the height of the tree?

— JohnFx (originally asked here)

Top Answer


Find a stick the length of your arm. Hold your arm out straight with the stick pointing straight up (90-degree angle to your outstretched arm). Walk backwards until you see the tip of the stick line up with the top of the tree. Your feet are now at approximately the same distance from the tree as it is high (provided the tree is significantly taller than you are, and the ground is relatively level).

Old logger method. Simple.

— Answered by shirlock homes

Alternative Answer: The Shadow Method

1. Measure your shadow. 2. Measure yourself. 3. Measure the tree's shadow. 4. Calculate (tree's shadow * your height) / your shadow = ~Tree Height.


You'll have to do this on a sunny day (you may need an assistant), and the ground will have to be relatively flat as a slope will throw off the measurement.

— Answered by Tester101

Alternative Answer: The Pencil Method

Take a pencil and move several meters away from the tree. Outstretch your arm and hold the pencil so that you can measure the height of the tree on the pencil with your thumb. Then turn the pencil at the base of the tree by 90 degrees. Note where the distance measured by thumb hits the earth and measure the distance from this point to the tree. This is the height of the tree.


— Answered by bennymo

Alternative Answer: The Mirror Method

1. Fill a black pan with water, this makes a great mirror during the day (it's best you don't use your best pan for this).


2. Place pan a known distance from the tree, call the distance from the middle of the pan to the tree B1 in the equations.

3. Stand back from the pan until you see the top of the tree in the middle of the reflection. Measure from your eye level to the ground, straight down, and call it A2. From that point on the ground to the center of the pan is B2.


4. You now have two right angle triangles that are proportional and only one unknown, the tree height (A1). A1/B1 = A2/B2 or A1 = A2 * B1 / B2. Or in English, the tree height is your height times the distance from the pan to the tree divided by the distance from you to the pan.

For example, if your eyes are 6' above the ground, the pan is 40' from the tree, and you stand 5' back from the pan, you get 6 * 40 / 5 or a 48' tree. For more accurate measurements, get yourself on top of a step ladder or some other high point.


Note that if you can't determine how level the ground is between you and the pan, you may be better off measuring from eye level to the pan and then do some geometry to get your height above the pan (A2 = square root(eye to pan squared / pan to foot squared)).

— Answered by BMitch

Alternative Answer: The Mobile App Method

You might try one of the existing smart phone applications like this one: Smart Measure.


— Answered by mfloryan

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