Retaining wall block calculator

Count by course rather than area alone

A face-area shortcut divides total wall area by the area of one block. That can be a useful early check, but it does not round the ends of each course or a partial top course. Course counting is a better starting point for an order list. This tool rounds the run of each course, rounds the exposed courses, adds your buried courses, and finally applies waste.

If a block is tapered, split-faced, or part of a modular pattern, use its effective installed coverage. Do not use the widest decorative face as a module length unless the manufacturer specifies that measurement. Enter special corners, half units and end units separately in your supplier schedule.

Order blocks = ceil(ceil(length ÷ module length) × (ceil(height ÷ module height) + buried courses) × (1 + waste/100))

What waste and pallet counts mean

Waste is an allowance for cuts, handling damage and uncertain takeoff details. Five, ten and fifteen percent are convenient planning choices, not measured product loss rates. The actual allowance depends on the layout, whether cuts can be reused, and your supplier’s returns policy.

The pallet count rounds the order quantity up to a whole pallet using the number of units you enter. The starting 75 units is illustrative, not a standard package across brands. Buying whole pallets can give you more units than the displayed unit takeoff. Check the product listing before approving delivery.

Example: a 20-foot wall

A 20-foot run with 16-inch-long units takes 15 units per course. At 3 feet exposed height with 6-inch units, there are six visible courses. One buried course brings the net count to 105 units. Ten percent waste produces 116 units to order.

Changing the exposed height to 37 inches adds a full course. The net count then becomes 120 and the order quantity becomes 132. This is why a small height change can move your purchase quantity more than an area-only calculation suggests.