How Many Concrete Blocks Do I Need?
Enter wall dimensions → get blocks, mortar bags, sand, and a purchase list.
Last updated: April 15, 2026
Standard load-bearing — Standard load-bearing walls
Results
Blocks Needed
189
180 base + 5% waste
Wall Area
160 sq ft
CMU Size
8×8×16
Mortar Bags
6 (80lb)
Sand Volume
0.86 cu yd
Total Cost
$709.5
Shopping Tips
- • 189 blocks ≈ 3 pallets
- • Blocks sold individually or by pallet at Home Depot/Lowe's
Planning numbers — actual quantities depend on your supplier and site conditions.
Worked Examples
| Project | Area | Blocks | Mortar | Sand (cu yd) | CMU |
|---|---|---|---|---|---|
| Garden Wall (10×4 ft) | 40 sq ft | 48 | 2 bags | 0.3 | 6×8×16 |
| Single Wall (20×8 ft) | 160 sq ft | 189 | 6 bags | 0.86 | 8×8×16 |
| Two-Car Garage (24×8 ft) | 192 sq ft | 227 | 7 bags | 1.0 | 8×8×16 |
| Basement Wall (40×8 ft) | 320 sq ft | 378 | 12 bags | 1.7 | 10×8×16 |
| Foundation Wall (50×8 ft) | 400 sq ft | 473 | 15 bags | 2.1 | 12×8×16 |
All examples include 5% waste. Blocks per sq ft = 1.125 for standard CMU.
Typical Cost Range
Concrete block (each)
$1.50 - $3.00
Mortar (80lb bag)
$6 - $10
Labor per block
$2 - $4
Prices vary by region. Get contractor quotes for full project cost.
Frequently Asked Questions
For standard 8×8×16 blocks, you need 1.125 blocks per square foot. A 20×8 ft wall (160 sq ft) needs about 180 blocks. Add 5% for waste — that's 189 blocks total. Just enter your dimensions above and it figures out the count for any CMU size, waste included.
One 80lb bag of mortar covers about 33-35 standard blocks with 3/8" joints. For 180 blocks, you need roughly 6 bags. Type S (1,800 psi) is for load-bearing walls; Type N (750 psi) works for non-structural walls. Turn on the mortar option above and you'll see bag count plus sand volume.
8×8×16 is standard for most walls. Use 12×8×16 for foundation walls (maximum strength), 10×8×16 for basement walls, 6×8×16 for interior partitions, and 4×8×16 for non-load bearing walls. Select your project type and the calculator auto-recommends the right size.
You need about 0.14 cu yd of sand per 80lb bag of mortar — roughly 1 cu yd per 7 bags. For 6 bags of mortar, that's about 0.86 cu yd of sand. Check the mortar box and the sand amount pops up in your results.
Yes for load-bearing and foundation walls — grout fills the hollow cores for structural strength. Full fill uses 0.5 cu ft per block, partial fill uses 0.25 cu ft. Non-structural walls don't need grout, but it adds strength if you want it.
Blocks run $1.50-3 each, mortar is $6-10 per bag, labor adds $2-4 per block. A 20×8 ft wall (189 blocks with waste) costs roughly $300-570 for blocks, $100-160 for mortar, $380-760 for labor — total $780-1,490. Foundation walls cost more due to grout and rebar.