Concrete Block Calculator
Calculate concrete blocks, mortar, and grout for your wall project.
Whether you call them Concrete Blocks, CMUs, or Cinder Blocks, our tool provides accurate estimates for all.
Last updated: January 28, 2026
Enter Wall Details
Above-grade exterior walls
标准承重墙 — Standard load-bearing walls
% (5% recommended)
Type S for load-bearing walls, Type N for non-structural
Results
Blocks Needed
189
180 blocks + 5% waste
Wall Area
160 sq ft
Mortar: 17 bags (80lb)
Cost Estimate
Blocks:$283.5
Mortar:$136
Labor:$378
TOTAL: $797.5
*Estimate only. Actual costs vary by location and contractor.
Shopping Tips
- • 189 blocks ≈ 3 pallets (standard: 90-100 blocks/pallet)
- • 17 mortar bags — available at Home Depot/Lowe's
- • Blocks sold individually or by pallet at most suppliers
How to Use This Calculator
- Select your project type — Foundation, retaining wall, interior, or exterior. The calculator will suggest the right block size.
- Choose CMU block size — 8×8×16 is standard for most walls. Use 12×8×16 for foundations, 6×8×16 for interior partitions.
- Enter wall dimensions — Length and height in feet or inches. The calculator uses actual block dimensions (7⅝×7⅝×15⅝ for 8×8×16).
- Add mortar and grout — Mortar is required for all walls. Grout is needed for load-bearing and foundation walls.
- Get your estimate — Review block count, mortar bags, grout volume, and total cost. Remember to get contractor quotes before starting.
How We Calculate
Blocks = Wall Area (sq ft) × Blocks per sq ft × (1 + Waste%)
Standard 8×8×16 blocks: 1.125 blocks per square foot
CMU Sizes (ASTM C90)
- • 4×8×16: 1.125 blocks/sq ft
- • 6×8×16: 1.125 blocks/sq ft
- • 8×8×16: 1.125 blocks/sq ft (standard)
- • 10×8×16: 1.125 blocks/sq ft
- • 12×8×16: 1.125 blocks/sq ft
Mortar Requirements
- • 8×8×16 blocks: 8.5 bags/100 blocks
- • Type S: Load-bearing walls
- • Type N: Non-structural walls
- • 80lb bags (Type S or Type N)
Example: 20×8 ft Wall with 8×8×16 Blocks
- Wall Area: 20 × 8 = 160 sq ft
- Blocks: 160 × 1.125 = 180 blocks
- With 5% waste: 180 × 1.05 = 189 blocks
- Mortar: (180 ÷ 100) × 8.5 = 16 bags
- Grout (full fill): 180 × 0.5 = 90 cu ft (3.3 cu yd)
Common Uses for Concrete Blocks
- Foundation Walls: Use 8×8×16 standard blocks with filled cores for structural strength.
- Retaining Walls: Requires proper drainage and may need reinforced blocks for walls over 4 feet tall.
- Garden Walls: Decorative 4×8×16 blocks work well for non-structural applications.
Mortar Requirements
Rule of thumb: 1 bag of mortar (80 lbs) covers 30-35 standard blocks with 3/8" joints.
- • For 100 blocks: 3-4 bags of mortar
- • For 500 blocks: 15-17 bags of mortar
Calculations based on ASTM C90 (CMU standards) and NCMA TEK 1-1F guidelines. Learn more