Retaining Wall Block Calculator
Retaining Wall Block Calculator
Enter your wall's length and height and the size of a single block to find how many blocks to buy — the result includes a standard 5% allowance for cuts and waste.
The 5% waste allowance is a smaller margin than paving projects typically use, reflecting the fact that retaining wall blocks are usually cut or trimmed far less often than pavers, since a wall's straight run has fewer awkward edges to fit around than an open paved area. Getting the block count right before ordering matters for retaining walls specifically because running short mid-build can leave a partially completed wall exposed to the elements (and to the soil pressure it's meant to hold back) for longer than planned while a follow-up order is placed.
- Imperial: Area per Block = (Length × Height in inches) ÷ 144; Blocks Needed = (Wall Area × 1.05) ÷ Area per Block. Example: 20×3 ft wall with 18×6 in blocks = 84 blocks.
- Metric: Area per Block = (Length × Height in cm) ÷ 10000; Blocks Needed = (Wall Area × 1.05) ÷ Area per Block. Example: 6×1 m wall with 45×15 cm blocks = 94 blocks.
- Note: this estimates the visible face blocks only, in either unit system — it does not include base/foundation blocks, capstones, or drainage gravel.
Does this include the base row or capstones?
No — this counts standard face blocks for the wall area only; add base course and capstones separately based on your specific block system.
Why is the waste allowance smaller than for pavers?
Retaining wall blocks are usually cut less often than pavers (fewer curves/edges in a typical straight or gently curved wall), so 5% is a common allowance versus 10% for pavers.
Retaining Wall Block Calculator
Enter your wall's length and height and the size of a single block to find how many blocks to buy — the result includes a standard 5% allowance for cuts and waste.
The 5% waste allowance is a smaller margin than paving projects typically use, reflecting the fact that retaining wall blocks are usually cut or trimmed far less often than pavers, since a wall's straight run has fewer awkward edges to fit around than an open paved area. Getting the block count right before ordering matters for retaining walls specifically because running short mid-build can leave a partially completed wall exposed to the elements (and to the soil pressure it's meant to hold back) for longer than planned while a follow-up order is placed.
- Imperial: Area per Block = (Length × Height in inches) ÷ 144; Blocks Needed = (Wall Area × 1.05) ÷ Area per Block. Example: 20×3 ft wall with 18×6 in blocks = 84 blocks.
- Metric: Area per Block = (Length × Height in cm) ÷ 10000; Blocks Needed = (Wall Area × 1.05) ÷ Area per Block. Example: 6×1 m wall with 45×15 cm blocks = 94 blocks.
- Note: this estimates the visible face blocks only, in either unit system — it does not include base/foundation blocks, capstones, or drainage gravel.
Does this include the base row or capstones?
No — this counts standard face blocks for the wall area only; add base course and capstones separately based on your specific block system.
Why is the waste allowance smaller than for pavers?
Retaining wall blocks are usually cut less often than pavers (fewer curves/edges in a typical straight or gently curved wall), so 5% is a common allowance versus 10% for pavers.