A red cedar is a type of tree commonly found on the North American continent. The red cedar is coniferous, meaning it drops cones that contain its seeds. If you'd like to estimate the age of your red cedar, you can do so by using a tape measure and some math. You might find that your red cedar tree is older than you think -- perhaps hundreds of years old.
Use your tape measure to measure the circumference of the red cedar at least 4 or 5 feet above the ground.
Enter the circumference measurement in inches into your calculator and divide that number by 3.14, or pi. This will give you the diameter of the tree.
Divide the diameter you just found by 2 to figure out the radius of the tree.
Deduct at least half an inch (0.5) from the radius if the tree has thick bark.
Divide the radius measurement by 0.05 -- the red cedar ring growth rate -- to determine the age of your red cedar. For instance, if the radius you found was 5 inches, your red cedar tree is approximately 100 years old.