Professional foresters, environmentalists and local loggers seeking firewood for the hearth at home may need, at one point or another, to find the weight of a tree. Estimating the weight of a tree will seem a formidable task---it is, after all, rather daunting to gaze up at one of nature's skyscrapers and wonder just how to place it on a scale---but it can become a simple undertaking with the use of basic math and approximate, naked-eye measurements.
Measure the diameter of the tree at approximately chest height in meters. Divide the diameter in half. This is the radius of the tree.
Measure the height of the tree with measuring tape, if possible. If the tree is too tall to measure directly, mark the tree at a fixed height, such as two meters, and estimate how many sections of that height will fit into the entire length of the tree. (This need only be a rough estimate of the actual height.)
Calculate the volume of the tree. Multiply the height by the radius squared, then multiply the resulting value by pi (which is approximately 3.14). The final answer will be in units of cubic meters.
Identify the type of tree. Take note of leaf patterns, size, wood colour and other such attributes; you may want to use a tree identification guidebook if you are uncertain of the tree's identity.
Look up the density of this tree type online. Different types of wood bear different density values, but most densities should be in standard units of "kilograms per cubic meter."
Multiply the volume of the tree by the wood density. The resulting value will be in kilograms: the approximate mass of the tree.