Vegas Hardscape Design

Free Tool

Retaining Wall Calculator

Enter your wall length and height to estimate how many blocks, how much compacted base, and how much drainage backfill you'll need for a garden or grading retaining wall.

Wall Dimensions
Enter the wall you plan to build and your preferred block size.
Estimated Materials
Rough quantities based on the inputs to the left.

60

Sq Ft Wall Face

198

Blocks Needed

0.5 tons

Base Material (0.4 cu yd)

3.1 tons

Drainage Backfill (2.2 cu yd)

Estimates only — actual block count, base depth, and drainage needs depend on your soil, wall height, and site grading. Book a consultation for an exact material plan on your project.

FAQ

Frequently Asked Questions

How many retaining wall blocks do I need?

Divide the total wall face area (length x height) by the face area of one block, then add a waste factor for cuts at corners and ends. A common small block measuring 12x4 in. covers 1/3 sq ft per unit, so a 20 ft long, 3 ft tall wall (60 sq ft) needs roughly 180 blocks before waste.

How thick should the base be under a retaining wall?

A minimum of 6 in. of compacted crushed base is standard under the first course, more for taller walls or soft/expansive soil. Getting this base level and well-compacted matters more than almost anything else — an uneven base is the top cause of retaining walls leaning or settling over time.

Why does a retaining wall need drainage gravel behind it?

Backfilling with clean, free-draining crushed stone (rather than native soil) lets water pass through instead of building up hydrostatic pressure behind the wall. Without it, saturated soil is one of the most common causes of retaining wall failure, especially after heavy rain.

Do I need a permit or engineer for a retaining wall in Las Vegas?

Many Southern Nevada jurisdictions require an engineered design and permit once a wall exceeds roughly 4 ft in height (measured from the bottom of the footing) or holds back a slope with a surcharge load — but rules vary by city and county. Always confirm current requirements with your local building department before starting a tall wall.

Is this calculator accurate enough to order blocks from?

It's a solid planning estimate for budgeting, not a final material order — actual block count, base depth, and drainage needs depend on your soil, wall height, and site grading. Our design process includes an engineered take-off for anything beyond a short garden wall.

Grading or sloped lot? Let's design it properly.

This calculator gives you a solid planning estimate. Retaining walls involve real engineering considerations — drainage, surcharge, and soil type — that our design process accounts for on your actual site.

Book a 3D Design Consultation