Concrete Block Calculator
Add wall lengths, heights and openings to estimate blocks by size, including extra.
How many blocks per square foot?
These are nominal face modules for US products, including the intended joint. Converting metres does not select a metric-sized product. Check your supplier’s face dimensions before ordering.
| Nominal face | Units per sq ft |
|---|---|
| Standard · 8 × 16 in | 1.125 |
| Half-high · 4 × 16 in | 2.25 |
How the concrete block calculator works
Net wall area = length × height − openings. Divide net area by the nominal face area, add your extra percentage, then round up to whole units. Walls with the same size are combined before rounding. Counts for different sizes stay separate.
Worked example
A 20 × 4 ft wall has 80 sq ft before openings. Using Standard · 8 × 16 in and 10% extra gives 99 blocks after rounding.
Before you order
- This is one layer (one wythe) of rectangular wall area. Add another wall for each additional layer.
- Nominal faces already include joints. Do not add a joint to these dimensions a second time.
- Extra is an adjustable allowance, not a detailed cut plan. Returns, corners, bonds, openings, caps and specialty units can change the order.
- No mortar, grout, pallet or unit weight estimate is included. Those depend on your specific product and wall design.