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Concrete Slab Calculator for a 4-Inch Driveway with 10% Waste

Estimate ready-mix cubic yards, 80 lb bags, sub-base material, and an entered rebar-grid geometry without turning a quantity tool into structural advice.

Enter slab dimensions

Geometry only. Obtain spacing and reinforcement design from local code or a professional.

Enter the slab geometry.

ReviewedJuly 14, 2026
FormulaVisible below

How this driveway concrete calculator works

cubic feet = length × width × thickness ÷ 12cubic yards = cubic feet × (1 + waste) ÷ 27bags = ceiling(cubic feet with waste ÷ bag yield)

Understanding your result

The 4-inch thickness and 10% waste are editable examples, not design recommendations. Site excavation, soil bearing, drainage, frost, slope, vehicle load, joints, reinforcement, and local code determine an appropriate assembly.

Frequently asked questions

How many 80 lb bags make one cubic yard?

At QUIKRETE’s nominal 0.60 cu ft yield, 45 bags equal 27 cu ft. Confirm the exact product label and round up to full bags.

Does a driveway need rebar?

Reinforcement depends on design and local requirements. This page only totals the length of a spacing value the user supplies; it does not select bar size, spacing, cover, laps, or reinforcement type.

Methodology & data sources

Important construction disclaimer

Quantity estimate only—not structural, geotechnical, code, drainage, or safety advice. Confirm design, utilities, permits, excavation, reinforcement, and order quantity locally.

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