Standard Patio Slab
A 20 ft × 12 ft patio slab at 4 inches deep using 3,000 psi mix.
- Length
- 20 ft
- Width
- 12 ft
- Depth
- 4 in
- Mix
- 3,000 psi
- Waste
- 5%
Result2.96 yd³ · ~$420 material cost
ACI 318 Compliant
Concrete Calculator
Calculate concrete volume, mix proportions, and material costs for slabs, columns, footings, retaining walls, and more — compliant with ACI 318.
Concrete Calculator
Enter your project dimensions to calculate concrete volume and material estimates.
Results
Concrete Calculator — Results
Concrete Volume
—
yd³
Concrete Volume (metric)
—
m³
Cement (94 lb bags)
—
bags
Sand
—
tons
Gravel / Aggregate
—
tons
Water
—
gal
Estimated Material Cost
—
These results are for reference only. Verify all calculations with a licensed professional engineer.
Formula
Volume = L × W × D
V = L × W × D
Where:
V = Volume (ft³ → convert to yd³ ÷ 27)
L = Length (ft)
W = Width (ft)
D = Depth (ft — convert from in ÷ 12)
Material quantities per ACI 211.1 mix design standards.The volume of a rectangular slab is calculated by multiplying length by width by depth. For columns, the formula uses π × r² × h. ACI 318 Section 6.2 specifies minimum concrete cover and strength requirements for each application.
| Variable | Description | Unit |
|---|---|---|
| V | Total concrete volume | yd³ / m³ |
| L | Length of slab or footing | ft / m |
| W | Width of slab or footing | ft / m |
| D | Depth or thickness | in / mm |
| w | Waste factor | % |
Example Calculations
Column Footing
A 3 ft × 3 ft × 2 ft deep footing for a structural column.
- Length
- 3 ft
- Width
- 3 ft
- Depth
- 24 in
- Mix
- 4,000 psi
- Waste
- 5%
Result0.67 yd³ · ~$110 material cost
How It Works
1
Enter dimensions
Input the length, width, and depth of your concrete element. Select the shape that matches your project — slab, column, footing, or wall.
2
Choose mix design
Select the appropriate concrete strength for your application. Higher psi ratings are required for structural elements per ACI 318.
3
Review results
Get instant volume calculations in cubic yards and meters, plus material breakdowns for cement, sand, gravel, and water based on ACI 211.1 mix design proportions.
4
Export report
Download a professional PDF report with all calculations, mix design details, and material quantities suitable for permit submission.
Concrete Calculator — FAQ
What is the difference between 3,000 psi and 4,000 psi concrete?
3,000 psi concrete is suitable for general-purpose applications like sidewalks, driveways, and patios. 4,000 psi concrete is used for structural elements like columns, beams, and footings where higher compressive strength is required. ACI 318 specifies minimum strength requirements based on structural application.
How much does concrete cost per cubic yard?
Concrete prices vary by region and mix design. As of 2026, expect $130–$180 per cubic yard for standard 3,000 psi mix, plus delivery fees. High-strength or specialty mixes cost more. Our calculator provides material cost estimates based on national average pricing.
What is the standard concrete mix ratio?
A standard 3,000 psi mix uses a 1:2:3 ratio (1 part cement, 2 parts sand, 3 parts gravel) by volume. Water-to-cement ratio is typically 0.45–0.50. ACI 211.1 provides detailed mix design procedures for achieving specific strength requirements.
Do you include rebar or reinforcement in the calculation?
The current calculator provides concrete volume and material estimates only. Reinforcement (rebar, wire mesh, fiber) is not included in the material cost estimate. We recommend consulting a structural engineer for reinforcement requirements per ACI 318.
Can I save my calculations?
Yes, with a BuildCal Pro account you can save calculations to your project dashboard, add notes, and export reports. Team plans allow sharing and collaboration.
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