The Concrete Wall Calculator calculates how much concrete you need for a poured concrete wall by multiplying its length, height and thickness and adding a waste allowance.
The result is shown in cubic yards or cubic meters, converted into bags of premixed concrete (40, 60 or 80 lb), and optionally priced if you enter a ready-mix price per cubic yard.
Concrete Wall Calculator
Concrete volume (cubic yards or m³) and bags of mix for a poured concrete or cement wall.
Formula
V = L × H × T × (1 + waste %)
Bags = V ÷ bag yield, rounded up
Ready-mix cost = V (yd³) × price per yd³
Where L = wall length, H = wall height and T = wall thickness.
How the Calculation Works
Step 1: Convert all dimensions to the same unit — for example, 8 in thickness = 0.667 ft.
Step 2: Multiply length × height × thickness and add waste.
Step 3: Divide cubic feet by 27 for cubic yards, or by the bag yield for bags.
Variables Explained
| Input | Meaning | Unit |
|---|---|---|
| Length, height | Wall size | ft, m |
| Thickness | Wall width | in, mm |
| Waste | Extra for spillage and form movement | % |
| Bag size | Premixed bag you plan to use | lb |
Example Calculation
Given: wall 20 ft × 8 ft, 8 in thick, 10% waste, 80 lb bags
Volume: 20 × 8 × 0.667 = 106.67 ft³
With waste: 106.67 × 1.1 = 117.33 ft³ ÷ 27
Result: ≈ 4.35 yd³, or 196 bags of 80 lb mix
Concrete Volume Reference
| Wall (per 10 ft of length, 8 ft high) | Volume before waste |
|---|---|
| 6 in thick | 40 ft³ ≈ 1.48 yd³ |
| 8 in thick | 53.3 ft³ ≈ 1.98 yd³ |
| 10 in thick | 66.7 ft³ ≈ 2.47 yd³ |
| 12 in thick | 80 ft³ ≈ 2.96 yd³ |
Bag yields used (from typical labels): 40 lb ≈ 0.30 ft³, 60 lb ≈ 0.45 ft³, 80 lb ≈ 0.60 ft³.
Material Estimation Notes
Footings are not included — use the Concrete Retaining Wall or Retaining Wall Footing calculator for wall-plus-footing pours. Rebar, forms and ties are separate. Ready-mix suppliers may have minimum orders.
Waste Factor Considerations
Form bulging, uneven subgrade and spillage all use extra concrete. The right allowance depends on your forms and site conditions.
Frequently Asked Questions
How many yards of concrete do I need for a wall?
Length × height × thickness in feet, divided by 27, plus waste.
How many bags of concrete for a wall?
Divide the volume in cubic feet by your bag’s yield.
How thick should a concrete wall be?
It depends on height, loads and code; use the thickness from your plans.
Is a cement wall the same as a concrete wall?
People often say cement, but walls are made of concrete (cement, sand, gravel and water).
How much does a yard of concrete weigh?
It varies with the mix; ask your supplier for their figure.