How to Estimate the Cost of a Rock Retaining Wall

Spray paint the ground to indicate the rock retaining wall's placement. Measure the length and write this down on a piece of paper. Divide the retaining wall's length with the rock's length to determine how many rocks it will take to reach end to end and write this down as well. For example, if your wall will be 14 feet long and your rocks are 8 inches long, it will take 21 rocks to reach end to end.

Determine the rock retaining wall's height. Generally, it is not recommended to build a retaining wall higher than 4 feet without using a more advanced system of mortaring the rocks together. Divide the wall's overall height with the rock's height to determine how many levels your wall needs. For example, if you want a wall 3 feet tall and your stones are 4 inches tall, you will need nine levels. Add one more level for the stabilizer level, which will be underground.

Multiply the number of stones per row by the number of rows needed. In the above example, you will need 21 rocks in 10 levels, meaning a total of 210 rocks. Purchase a few extra rocks in case some become damaged during the building process or some of your measurements were off.

Take the number representing the total number of rocks to your local garden center and multiply the number of rocks you need by the price of each rock. If each rock costs you $1.29 and you need 210, you will spend a total of $271 on the rocks.