Measure the length of the tree’s shadow, also in inches. You may want to use feet and inches and use the CSGNetwork converter to convert feet and inches to inches. Use your measuring tape to determine the length of the tree’s shadow from the base center of the tree to the tip of the shadow. This works best if the ground all along the shadow is fairly level; if the tree is on a slope, for example, your measurement won’t be entirely accurate. On level ground, this is SO accurate it is scary! Stand next to the tree or the object to be measured. For best results, do this method on a bright, sunny day so that you can tell exactly where the shadow’s tip is. Measure the length of your shadow, also in inches (you can use yards, feet, inches, meters, centimeters, whatever as long as they are ALL the same... Our calculator designates inches but you can use what you wish...). Use a tape measure or yardstick to measure your shadow from the center point of your feet (heel to toe) to the tip of your shadow. You want to do this as quickly as possible after measuring the tree's shadow, since the sun’s position in the sky (and hence the shadow length) is slowly but constantly changing.
Calculate the tree’s height by using the proportion of your shadow’s length to your height. Since you know the length of the tree’s shadow, and you also know that a certain height (your height) produces a certain shadow length (the length of your shadow), you can determine the tree’s height with a little math. Multiply the length of the tree’s shadow by your height, and then divide the resulting number by the length of your shadow. For example, if you are 5 feet tall, your shadow is 8 feet long, and the tree’s shadow is 100 feet long, the height of the tree is (100 x 5) / 8 = 62.5 feet. Note that the order of your multiplication does not matter. For more of an explanation of ratio and proportion, see the CSG Ratio Proportion Calculator - Basic Algebra Tutor. This does not work with ANY version of FireFox as of 5/2007.