The Blocks for Retaining Wall calculator computes the number of landscape blocks needed for a retention wall. 
INSTRUCTIONS: Choose units and enter the following:
- (L) Length of Retention Wall
- (H) Height of Retention Wall
- (M) Choose Block Size
- 5-1/2 x 18, 3-1/2 x 11-1/2, 5-1/2 x 11-1/2, 6x17, 8x18
Blocks for Retaining Wall (nB): The calculator returns the approximate number of units (blocks) needed to build the retention wall.
The Math / Science
The calculator computes the face area (LxH) and then uses that to compute the number of blocks needed per row and the number of rows. This computes the number of blocks in a wall that is one deep.
A Retention Wall is a vertical or diagonal wall structure used to retain soil or 
water at an elevated height on one side of the wall, keeping it above the natural level that the soil or water would achieve. Retention walls are used to create relatively flat areas such as roads or gardens that are cut into a hillside. Retention walls are also used as levees to keep water out of an area. The soil and moisture on one side of the wall exerts pressure (stress) on the wall. This is why the materials used must be appropriate for the application in both density and porosity.
Retention Wall Calculator Functions
- Blocks for Retaining Wall
- Railroad Ties for Retention Wall
- 4x4s for Retention Wall
- 6x6s for Retention Wall
- Boussinesq Equation for Wall Stress
- Horizontal Stress on Simple Retaining Wall
- Number of Sandbags Needed for a Dike or Wall
- Gabion Basket Wall
- Gabion Wall Ring