Concrete Calculators | Free Construction Calculators
Calculate concrete volume, weight, and material requirements
Concrete Slab Calculator
Calculate concrete needed for slabs
Concrete Bag Calculator
Calculate bags of concrete needed
Concrete Yard Calculator
Calculate cubic yards of concrete
Concrete Weight Calculator
Calculate weight of concrete
Concrete Volume Calculator
Calculate concrete volume for various shapes
About Concrete Calculations
Accurate concrete calculations are essential for cost estimation, material ordering, and project planning. Whether you're pouring a slab, building footings, or creating a driveway, knowing exactly how much concrete you need prevents costly over-ordering or project delays from under-ordering. Our professional concrete calculators help contractors, builders, and DIY enthusiasts determine volume in cubic yards, estimate bag quantities, calculate weight for structural considerations, and plan material deliveries efficiently.
Why Use Our Concrete Calculators?
Accurate Material Estimates
Calculate exact concrete quantities to avoid waste and shortages, saving money on materials and reducing project delays.
Cost Planning
Determine whether to use ready-mix or bagged concrete based on volume, and estimate total material costs for budgeting.
Multiple Shape Support
Calculate concrete for slabs, cylinders, columns, footings, stairs, and irregular shapes with specialized formulas.
Weight Calculations
Determine concrete weight for structural engineering, truck capacity planning, and foundation load requirements.
Professional Accuracy
Industry-standard formulas ensure calculations match real-world concrete delivery and construction requirements.
Common Concrete Calculations
Slab Volume
Calculate cubic yards for rectangular slabs: multiply length × width × thickness (in feet), divide by 27. Essential for patios, garage floors, and driveways.
Bag Estimation
Determine how many 60-lb or 80-lb bags needed for small projects. Compare cost of bagged vs ready-mix concrete.
Footing Calculations
Calculate volume for continuous strip footings and individual pad footings based on dimensions and depth requirements.
Cylindrical Pours
Compute concrete for columns, posts, and round structures using radius and height measurements.
Weight Determination
Calculate total weight based on volume and concrete density for structural design and truck load planning.
Waste Factor
Add appropriate overage percentage (typically 5-10%) to account for spillage, irregular surfaces, and slight miscalculations.
Frequently Asked Questions
How do I calculate how much concrete I need?
To calculate concrete needed, multiply length × width × depth (in feet) to get cubic feet, then divide by 27 to convert to cubic yards. For a 10×10 ft slab that is 4 inches (0.33 ft) thick: 10 × 10 × 0.33 = 33 cubic feet ÷ 27 = 1.22 cubic yards. Always add 5-10% extra for waste and spillage.
How many bags of concrete do I need for a project?
An 80-lb bag of concrete yields approximately 0.6 cubic feet. Divide your total cubic feet by 0.6 to find bags needed. For example, 33 cubic feet requires 55 bags (80-lb). A 60-lb bag yields about 0.45 cubic feet. Using pre-mixed bags is convenient for small projects under 2 cubic yards.
How much does concrete weigh per cubic yard?
Standard concrete weighs approximately 4,050 pounds (2 tons) per cubic yard. Lightweight concrete weighs 2,000-3,000 lbs/yd³, while heavyweight concrete can exceed 6,000 lbs/yd³. Weight varies based on aggregate type, water content, and reinforcement. This matters for structural calculations and delivery truck capacity.
What is the standard thickness for a concrete slab?
Residential garage slabs are typically 4 inches thick. Driveways should be 4-6 inches depending on vehicle weight. Basement floors are usually 4 inches. Commercial slabs range from 6-8 inches. Footings are typically 8-12 inches thick and twice the width of the wall they support. Local building codes specify minimum thicknesses.
Should I order ready-mix concrete or use bags?
Ready-mix concrete is more economical and efficient for projects over 2 cubic yards (about 1.5 tons of bags). It provides better consistency and saves significant labor. Use bagged concrete for small repairs, post holes, or projects under 1 cubic yard. Ready-mix typically costs $100-150 per yard delivered, while bags cost $4-8 each.
How do I convert cubic feet to cubic yards for concrete?
Divide cubic feet by 27 to get cubic yards (1 yard = 3ft × 3ft × 3ft = 27 cubic feet). For example: 81 cubic feet ÷ 27 = 3 cubic yards. Most concrete is ordered by the cubic yard. Concrete trucks typically carry 10 yards maximum, with 8-9 yards being a practical full load.
Professional Guidance
Concrete calculations should account for local conditions, project requirements, and building codes. Always verify measurements on-site, consult with ready-mix suppliers about mix designs, and consider factors like weather, pour rate, and finishing time. For structural applications, consult a licensed engineer.