How many concrete blocks for a 40 ft long, 6 ft high wall?

A 40 ft long, 6 ft high wall (240 sq ft) needs 270 standard 8×8×16 blocks — buy 284 with 5% extra — laid in 9 courses, plus about 22 bags of 80 lb mortar mix.

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Quikrete Mortar Mix: up to 13 blocks per bag.

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Your results

8×8×16 blocks needed284
80 lb bags of mortar mix22
Wall area240 sq ft
Courses (rows) high9
How many concrete blocks for a 40 ft long, 6 ft high wall — diagram

Breakdown

  • Blocks per course: 30 (each block covers 16 in of length)
  • Courses: 9 (8 in each)
  • Total: 270 blocks, 284 with waste
  • Mortar: 22 bags of 80 lb mix

Need cores filled? Grout and rebar quantities depend on the engineering of the wall; retaining and foundation walls need a design that meets local code.

The math

40 × 6 = 240 sq ft × 1.125 = 270 blocks × 1.05 waste = 284 blocks · ÷ 13 per bag = 22 bags

Common questions

How many blocks for a 40x6 wall?

270 standard 8×8×16 blocks, or 284 with 5% waste.

Want the full method, tips and other sizes? See the concrete block calculator guide.

Last reviewed November 1, 2026. Results are estimates — confirm with your supplier.

Similar sizes

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