Giant sequoia trees are the largest trees by volume in the world. Many giant sequoias are between 250 and 300 feet tall, the tallest being about 325 feet high. While their height is impressive, the real wonder of a giant sequoia lies in its bulk. Many of these giants have diameters in excess of 30 feet near the ground, with a corresponding circumference of over 94 feet!

The largest tree in Calaveras Big Trees State Park is the Louis Agassiz tree. It is located in the South Grove. This tree is "only" 250 feet tall, but it is over 25 feet in diameter six feet above the ground! The largest tree in the North Grove is probably the Empire State Tree, which is 18 feet in diameter six feet above the ground.

Most trees have their diameter measured at breast height, which is considered to be four and a half feet above the ground on the uphill side of the tree. Giant sequoias however, are measured at six feet above the ground. This is because of the major increase in circumference at the lower end of the tree. This "butt swell" helps the tree in a couple ways. It adds stability to the tree, just as a wide stance adds stability to a football player. Also, it helps deflect falling vegetation away from the base of the tree. This decreases the chances of the giant sequoia being injured by fire when that debris eventually burns.

Mature giant sequoia with snow around the base.