Concrete Calculator
Calculate the exact amount of concrete needed for your project. This free concrete calculator helps you determine cubic yards, bags of concrete mix, and total material requirements for slabs, footings, columns, and foundations.
Professional Concrete Calculator
Industry-standard material calculations based on ACI, IBC/IRC, and DOT specifications
Project Type
Dimensions
Specifications
Residential driveways, garage floors, standard slabs
About This Calculator
Industry Standards
- ACI 318 structural concrete code
- International Building Code (IBC/IRC)
- DOT specifications for driveways
- ASTM material standards
Key Specifications
- 60 lb bag yields 0.45 cu ft
- 80 lb bag yields 0.60 cu ft
- 1 cubic yard = 27 cubic feet
- Standard waste factor: 5-10%
Professional Note: This calculator provides estimates based on industry standards. Always consult local building codes, obtain necessary permits, and consider hiring a licensed contractor for structural projects. Actual material requirements may vary based on site conditions, formwork, and installation methods.
Frequently Asked Questions
What is a cubic yard of concrete?
A cubic yard is 27 cubic feet of concrete (3 feet × 3 feet × 3 feet). This is the standard measurement for ready-mix concrete delivery. One cubic yard weighs approximately 4,000 pounds and covers 81 square feet at 4 inches thick.
How many 80-lb bags of concrete do I need per cubic yard?
Each 80-lb bag yields approximately 0.6 cubic feet when mixed. One cubic yard requires 45 bags of 80-lb concrete mix. For 60-lb bags, which yield 0.45 cubic feet each, you need 60 bags per cubic yard.
What thickness should a concrete slab be?
IRC code requires 3.5 inches minimum for residential slabs-on-grade. Standard practice is 4 inches for garage floors, patios, and basement slabs. Driveways carrying passenger vehicles need 4-5 inches, increasing to 6 inches for RV and heavy truck traffic. Always verify local building code requirements.
Why add waste factor to concrete calculations?
ACI recommends 5-10% waste factor for spillage, over-excavation, uneven subgrade, and form irregularities. Simple rectangular slabs typically need 5-7% extra. Complex pours with multiple sections, steps, or difficult access require 10-15% waste factor.
Industry Standards Referenced
ACI 318 - Building Code Requirements for Structural Concrete(ACI 318-19)
View StandardProvides comprehensive standards for concrete design, construction, and inspection. Covers mix design requirements, reinforcement specifications, formwork standards, and construction practices for structural concrete.
Key Requirements:
- •Minimum 28-day compressive strength: 2,500-5,000 PSI based on application
- •Concrete cover requirements: 2" minimum for slabs on grade, 3" for exposed concrete
- •Maximum water-cement ratio: 0.45 for exterior exposure, 0.50 for interior
International Residential Code (IRC) - Section R403(IRC 2021)
View StandardGoverns residential foundation and footing requirements. Specifies minimum footing dimensions, depth below frost line, and concrete strength requirements for residential construction.
Key Requirements:
- •Footings must extend minimum 12" below undisturbed ground
- •Footings must be below frost line (varies by region)
- •Minimum footing width: 12" for one-story, 15" for two-story
- •Minimum concrete strength: 2,500 PSI
ASTM C94 - Ready-Mixed Concrete Specifications(ASTM C94/C94M)
View StandardDefines requirements for ready-mixed concrete including materials, production, delivery, and testing. Ensures consistency and quality control in commercial concrete supply.
Key Requirements:
- •Maximum delivery time: 90 minutes from batching
- •Maximum 300 drum revolutions during transport
- •Slump testing required before discharge
- •Temperature limits: 50-90°F at placement
Department of Transportation (DOT) Concrete Specifications(Varies by State DOT)
State-specific requirements for concrete used in transportation infrastructure. Generally requires higher strength concrete (4,000-5,000 PSI) and specific air entrainment for freeze-thaw resistance.
Key Requirements:
- •Typical minimum strength: 4,000 PSI for roadways
- •Air entrainment: 5-8% for freeze-thaw protection
- •Specific aggregate gradations and maximum sizes
Standards Disclaimer: Standards and codes are subject to periodic updates. Always verify current requirements with local building authorities and professional engineers before beginning construction. Links provided are for reference only.
Want to Learn More?
ACI 318 standards, bag yields (60lb/80lb), ready-mix specifications, and IRC/IBC code requirements for slabs, footings, and walls.
Read the Concrete Calculation GuideHow to Use This Calculator
- Enter dimensions: Input the length, width, and thickness of your concrete pour.
- Select project type: Choose from slab, footing, column, or stairs.
- Review results: See cubic yards needed and number of bags required.
- Add waste factor: The calculator includes a 10% waste factor.
Understanding Concrete Measurements
Concrete is measured in cubic yards (27 cubic feet). A typical 80-lb bag covers approximately 0.6 cubic feet. For large projects, ready-mix concrete is more economical than bagged mix.