Checkable example
A 5 × 4 × 0.10 m slab has a geometric volume of 2 m³. With 10% waste: 2.2 m³ or 2,200 L. At an illustrative 20 L/bag, you need 110 bags; at 8 per bag, the cost is 880. Ready mix at 100 per m³ would cost 220.
Using the estimate
The 20 L yield and prices are examples, not universal values. QUIKRETE describes bag quantities as approximate, rounded up, and dependent on product data sheets. Its calculator notes that uneven ground and waste may change quantities. This tool takes waste as an explicit input.
For rectangular slabs or pieces. Enter every dimension in meters; this tool does not design structures or determine strength.
Quantity estimate only. Thickness, reinforcement, strength, joints and design require professional judgment. No cement, sand or gravel mix proportions.
Frequently asked questions
Multiply length, width and thickness in meters by the number of pieces, then add your chosen waste percentage.
Divide the required concrete liters by the stated yield in liters per bag and round up. Bag weight alone does not determine yield.
No. You enter thickness and the tool estimates quantities. It does not design structures or prescribe mixes.