How to use it
- Enter length and width in feet.
- Input thickness in inches.
- Click Calculate to see results.
Planning a concrete slab? This calculator tells you exactly how much Sakrete 80-lb bag mix you need — no guesswork, no over-ordering.
Enter your slab's length and width in feet, plus thickness in inches. The tool returns three numbers: cubic feet (total volume), cubic yards (useful for ready-mix orders), and bags of 80-lb mix (since each bag yields about 0.6 cubic feet).
Why it matters: buying too little means delays and cold joints; buying too much wastes money. The bag count helps you shop precisely at the yard. Round up to the next whole bag — partial bags aren't sold.
Use the cubic yard figure when ordering truck delivery, and the cubic feet figure for manual mixing verification. All results update instantly as you adjust dimensions.
Pro tips
- Add 10% waste allowance for spills, over-excavation, and uneven subgrades.
- Round up bag counts to whole bags — partial 80-lb bags aren't sold.
- Order concrete by cubic yards for truck delivery; round up to the nearest quarter-yard.
- Don't forget to subtract volume for rebar, conduit, or post holes embedded in the slab.
Real-life examples
- Pouring a 12×12 shed floor at 4 inches thick.
- Setting fence posts with concrete footings.
- Repairing a cracked driveway section.
Case study
Maria needed a 10×10 patio at 4 inches thick. Before using the calculator, she ordered 2 cubic yards and had 0.5 yard left over — wasted $90. After calculating precisely, she ordered 1.25 yards with a 10% waste buffer, spent less, and had zero leftover mix.