Cutting down a tree, especially a large one, is a difficult task requiring a great amount of concentration. According to the University of Minnesota, a large tree will not, once cut and begun its descent, be possible to guide by hand. Before attempting to cut down a tree, it is important to make an estimate of the height and ensure no obstacles are in the way. Wear a full array of safety equipment during the felling, including safety glasses, work gloves and a hard hat.
Estimate the height of the tree using a stick that is as long as your hand. Hold the stick vertically, with your hand at the base, and the top of the stick at eye level. Facing the tree, walk slowly backwards, keeping your eyes on the base of the tree trunk, which should be visible over your lower hand. Once the top of the stick appears level with the top of the tree, stop and make a mark in the soil. Measure from the tree base to the mark, in feet; that is the estimated height of the tree.
Determine the direction the tree is naturally leaning in, as this will be the direction it will fall in. Measure the distance between the tree and all possible obstacles in the area. Ensure all obstacles are within safe distance of the tree.
Determine an escape path from the falling tree. The University of Minnesota recommends having two escape routes planned in case one is compromised.
Make an undercut on the tree using your chainsaw. The undercut guides the tree in its descent. Cut the tree on the side it is naturally leaning towards, to ensure the tree falls in that direction. Make one large cut one-third of the way through the tree; then, at a 45-degree angle, make another cut that meets the first cut at the end, making a wedge shape.
Start a cut at the back of the tree, that is, 1 or 2 inches above the undercut. This is called the back cut. The back cut relieves the stress being held by the undercut, causing the tree to fall in the direction of the undercut.
Run as soon as the tree begins to fall, in the direction of your escape route.