Although there is no set length or girth for a caber, the caber should be at a weight where at least 2/3 of all competitors can cause the caber to rotate over the top at 90 degrees to the ground. If an entire round commences with no competitors tossing a 90 degree throw the head judge has the right to shorten the caber from the thick end until it is a weight that can be properly thrown.
The caber is placed on end before the competitor picks it up, with the thicker end on top. As soon as the caber is lifted a turn has begun, and if the bottom touches the ground before the caber is thrown the turn is forfeited. Before throwing the caber a competitor is allowed to take as long a run as needed, within the judge's established parameters, to perform his throw.
Although only one judge is needed, at least two judges are recommended, with one behind the competitor to watch the angle, and a second judge in the field. The boundaries of the field are set at the judge's discretion, with the ability to close off an area as foul for the sake of protecting the fans left up to the head judge.
For a toss to be a legal caber toss the caber must travel completely vertical in its path, 90 degrees relative to the ground. A throw that does not travel 90 degrees over the top cannot beat a throw that travels at a 90 degree angle, regardless of finishing positions.
Caber tossing is not scored based on the distance that the caber is tossed, but instead by the angle that the caber falls relative to the thrower. The best possible throw is one that crosses over at 90 degrees to the ground, then finishes at 12 o'clock (with the thrower at 6 o'clock), or with the small end pointing directly away from the thrower. The closer to 12 a throw is the better it is, with illegal throws ranked based on how close to 90 degrees the caber reached.