Retaining Wall Calculator and Price Estimator

Calculate how may retaining wall blocks are needed and how much base and backfill gravel required. Optionally enter cap block dimension to include the cap row in the estimate and enter the price per block to get a cost estimate.

Wall Dimensions

Block Dimensions
Optionally enter the price per block

Cap Block Dimensions (optional)
Optionally enter the price per cap block

Wall Block Material Estimate:

40 Blocks (12" x 6")
10 Cap Blocks (12" x 4")
0.22 yds3 Base Gravel
0.86 yds3 Backfill Gravel
Estimated Material Cost
$200 Blocks
$50 Cap Blocks
$3 Base Gravel
$10 Backfill Gravel
$263 Estimated Total

Installation Overview:

20.00 ft2 Wall Area
10' Wall Width
2' 4" Wall Height
This wall is higher than the requested wall height based on the provided block size

Using the Retaining Wall Calculator

Retaining walls can be built using a multitude of materials, but they’re most commonly built using wall blocks or timbers.

To estimate retaining wall materials using the calculator simply enter the wall length and width and the preferred block dimensions.

Get Free Project Estimates

Find Qualified Retaining Wall Professionals in Your Area

If the cap row will use a different style of block then enter those dimensions separately to get an estimate for the cap blocks as well.

Estimate the retaining wall cost by adding the price per block. For example, you can estimate a 10′ wide by 2′ high retaining wall and observe the materials required.

If you’re building a concrete block wall, then check out our concrete block calculator.

How Many Retaining Wall Blocks Do You Need

Find how many retaining wall blocks are needed to build a wall

Estimating the number of retaining wall blocks you need requires estimating the number of rows and columns that are needed for the wall.

Start by measuring the wall width and height. We recommend embedding the first course of blocks below grade about 10% of the wall height to support the wall correctly. If the desired wall height is 6 feet, the wall should be embedded below grade by 7-8 inches. Be sure to account for this when measuring the height of the wall.

Divide the width of the wall in inches by the width of the block and round up, this is the number of columns. Divide the height of the wall in inches by the height of the block and round up, this is the number of rows. If the top row will be a cap block, then the number of cap blocks needed is the number of columns. To find the total number of blocks needed for the wall simply multiply the number of columns by the number of rows; don’t forget to subtract a row if using cap blocks.

Retaining Wall Estimation Tips

Ordering additional retaining wall materials, including blocks and cap blocks is a good idea to account for waste or bad material. We recommend ordering an additional 10% of materials to accommodate this. Don’t forget to account for embedding the first course of blocks below grade when measuring the desired height of the wall. Accounting for this from the start will ensure that the wall does not end up too short. If the wall is too high, you may need to embed it deeper in the ground to reach the desired height, this is a little more digging but is otherwise ok. See our retaining wall cost guide to find the average price of a retaining wall.

Preparing the Retaining Wall Base

The retaining wall should be set embedded below grade on a level base of 6″ gravel or stone. We recommend making the base twice as wide as the block depth to account for settling. The calculator will estimate this or use our cubic yardage calculator to estimate 6″ of gravel to find how much gravel material you’ll need to order. Ensure that the retaining wall base is compacted and level so that the first course of retaining wall block will be level.

Estimating Backfill Gravel for the Retaining Wall

The retaining wall should have 12″ of gravel immediately behind the entire length and height of the wall to allow for proper drainage. The calculator above will estimate this or, you can use the cubic yards calculator. Add a layer of landscape fabric between the stone backfill and the earth behind it to prevent the dirt from filling the pores of the gravel, making it less effective. is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to