Concrete Block Calculator
Calculate concrete blocks needed, mortar requirements, and project costs for walls and foundations
Calculate Concrete Block Requirements
Height of the wall to be built
Width or length of the wall
Enter local price per concrete block
Account for breakage and cutting (10% recommended)
Concrete Block Requirements
Block Size: 16" × 8" × 8" Standard Block
Blocks without waste: 0.0 blocks
With 10% waste factor: 0.0 blocks (rounded up to 0)
Mortar estimation: Based on 3 bags per 100 blocks rule
Project Analysis
Example Calculation
Garden Retaining Wall Project
Project: 10 ft wide × 3 ft high retaining wall
Wall area: 10 × 3 = 30 square feet
Wall area in square inches: 30 × 144 = 4,320 sq in
Block size: 16" × 8" standard block = 128 sq in per block
Blocks needed: 4,320 ÷ 128 = 33.75 blocks
With 10% waste: 33.75 × 1.10 = 37.1 ≈ 38 blocks
Cost Breakdown
38 blocks × $1.50 per block = $57.00
Mortar bags: 38 ÷ 33.3 = 1.14 ≈ 2 bags
Cost per square foot: $57.00 ÷ 30 sq ft = $1.90/sq ft
Note: Add costs for mortar, rebar, foundation, and tools
Common Block Sizes (inches)
Standard 16" × 8" blocks are most common for walls
Block Types
Hollow Core
Lightweight, insulation
Most common type
Solid
High strength
Load-bearing walls
Split-Face
Decorative texture
Retaining walls
Construction Tips
Add 10% extra blocks for waste and cutting
Use 3 mortar bags per 100 blocks (rule of thumb)
Ensure proper foundation for structural walls
Check local building codes for permits
Consider rebar reinforcement for tall walls
Understanding Concrete Block Calculations
How to Calculate Blocks Needed
To calculate the number of concrete blocks needed, you divide the total wall area by the area of a single block. Both measurements must be in the same units (typically square inches for precision).
Step-by-Step Calculation
- 1.Calculate wall area: height × width
- 2.Calculate block area: block height × block width
- 3.Divide wall area by block area
- 4.Add waste factor and round up to whole blocks
Mortar Requirements
General Rule:
- • 3 standard bags of mortar per 100 blocks
- • Each bag typically covers 33.3 blocks
- • Standard mortar bag weighs 80 pounds
- • Always round up to whole bags
Factors Affecting Mortar Use:
- • Joint thickness (typically 3/8")
- • Block size and type
- • Weather conditions
- • Mason's experience level