Everyday
Retaining Wall Block Calculator
Enter your wall length and exposed height, pick a block, and the page works out block count with the buried course included, base gravel and drain rock tonnage, caps, and material cost.
How it works
Behind the numbers
Most block estimates start from the visible wall and forget the part underground. This calculator starts with your exposed height, then adds the buried course using the industry rule: one full block height or 10% of total height, whichever is greater. That total height drives the course count.
Block count comes from courses times blocks per course, with waste set by your layout: 10% for straight runs, 15% for corners or curves. Base gravel is figured as a 6 in deep compacted bed, and drain rock as a 12 in column behind the wall, both converted to tons so you can order by the truckload.
The delivery section totals every ton (blocks, base, drain stone, caps) and estimates pallets, so you know whether you need dump-truck access. The $35 per face square foot installed figure is a published reference for budgeting, not a quote.
FAQ
Questions, answered
How many blocks do I need for a retaining wall?
Divide wall length by block face length for blocks per course, then multiply by courses (total height including the buried course divided by block height). Add 10% waste for straight runs, 15% for corners or curves. The calculator does this and rounds up.
How deep should the buried course be?
Bury one full block height, or 10% of the total wall height, whichever is greater. A 3 ft exposed wall with 8 in blocks buries 8 in. This keeps the wall from sliding and is the rule most installers follow.
How much gravel goes behind a retaining wall?
Plan a 12 in wide drain column behind the wall, from the base up to 6 in below the top. The calculator converts that volume to tons at about 1.4 tons per cubic yard of crushed stone.
Do I need an engineer for a retaining wall?
Most jurisdictions require an engineered design for walls over 4 ft tall measured from the bottom of the footing. Shorter garden walls are common DIY projects, but check local code first.