How to Calculate Boulders in Tons

Hunker may earn compensation through affiliate links in this story.
Image Credit: bubblea/iStock/GettyImages
See More Photos

Boulders can be millions or even billions of years old, and they are formed in different ways. If the need to move a boulder arises, you might need to calculate boulders in tons so you can determine how best to proceed. It's also worth considering whether you should attempt to move the boulder at all, or if you should either leave it where it is or obtain the assistance of a professional with heavy equipment.


Video of the Day

Guidelines for Moving Boulders

Natural processes like heating and cooling bind materials together, and over time, large, dense boulders can form. If left undisturbed, giant boulders can exist in their home environments for millennia. This is no doubt partially due to their incredible heft.


Business owners and homeowners may have boulders on their properties that were there originally or were added when the landscaping was done. If the boulder is unattractive or in the way, or if it would look better elsewhere, moving it could be an option. When boulders are very large, it may be best to consult a landscaper to do the job. Otherwise, it may be possible to move it securely with the proper tools and safety precautions.


To move a boulder, you may need a tape measure, a 4-foot pry bar and a ratcheting lever hoist. Be sure to don a pair of safety goggles and wear protective gloves and sturdy shoes. Dropping a boulder on one's foot could cause serious injuries. Once you have your tools and gear, the next step is to figure out approximately how many tons the boulder weighs.

Calculating a Boulder’s Weight

The ton is the largest unit for measuring weight in the United States, and since boulders can be one of the heaviest items on the planet, it makes sense to weigh boulders in tons. It is important to know what type of rock your boulder is made from, as this will help with your calculations. There are online guides that provide information about different types of rocks, so these should be consulted first if you know the type of rock. Then, take your tape measure (you might need a friend to help) and measure the boulder's length, width and height as best as you can.


Round each measurement to the nearest foot and then multiply them to get the total cubic feet. As an example, if the boulder measures 10 x 5 x 8 feet, the boulder is 400 cubic feet. If the boulder is granite, you can then use online resources like Stoneyard to determine that its weight averages about 172.5 pounds per cubic foot (ranging from 160 to 185 pounds). This is one of the heaviest boulder materials you might encounter.


Multiply 400 x 172.5, and you get 69,000 pounds. Since 1 ton weighs 2,000 pounds, you divide 69,000 by 2,000 and get 34.5 tons. The tonnage will determine whether or not you can move the boulder on your own.

Rolling the Boulder

Rolling may work with smaller boulders, but be sure that the area over which you are rolling it is level; otherwise, you could lose control of the rock. A scrap piece of wood and your pry bar can be used to carefully push or roll the boulder, but it is strenuous work. You can lay down pieces of pipe or wooden planks over which to roll it, but you will need to keep moving these as the boulder rolls. Small boulders can also be dragged by placing them in the middle of an old tire, a strong sled or another draggable item.


A ratcheting lever hoist can help nudge out a stubborn boulder. These have nylon straps, which are good for gripping a boulder's rough surface. The other end of the hoist can be attached to a truck's trailer hitch, a tree or another immovable object. Once the boulder is secure, the lever can be turned.

Again, for most boulders of substantial size, you won't be able to move them on your own. It's best not to try since this could lead to injury or property damage, if an errant boulder crashes into your home, for example. Instead, contact a landscaping company or stone supplier who might have cranes and trucks capable of carrying the boulder.