How to use this calculator
- Enter the planned wall length and height.
- Enter the face width and face height of the selected block.
- Set a waste allowance.
- Calculate courses, blocks per course, and whole blocks.
How the calculation works
Courses and blocks per course are each rounded up from the entered dimensions. Their product forms the base count; waste is then applied and the purchase quantity is rounded up.
Formula
Courses = wall height ÷ block face height, rounded up Blocks per course = wall length ÷ block face width, rounded up Purchase blocks = courses × blocks per course × (1 + waste % ÷ 100), rounded up
Worked example
A 20 ft long, 3 ft high wall using blocks with a 16 in × 6 in face needs 6 courses and 15 blocks per course. The base count is 90; with 5% waste, the result rounds up to 95 blocks.
Project considerations
- This is a material quantity estimate, not structural design.
- It does not determine allowable height, embedment, reinforcement, drainage, loads, or code compliance.
- Corner units, caps, cuts, curves, and manufacturer-specific installation details require separate planning.
Frequently asked questions
Does this tell me whether the wall is safe?
No. It only counts units from dimensions you enter and makes no structural or code determination.
Why are courses rounded up?
A partial remaining height or length still requires another full row or block before waste is considered.