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PRACTICAL HOME PROJECT MATH

Concrete volume calculator

Estimate rectangular slab volume and bag count using your product’s stated yield.

Flat rectangular area. Depth and bag yield are editable examples, not project specifications. Confirm the product label and required depth.

YOUR PLANNING ESTIMATE

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Enter your measurements

See the calculation

The calculation

Length × width × depth in inches ÷ 12 gives cubic feet. Apply your chosen allowance, then divide by 27 for cubic yards. Bag count uses the product’s volume yield, not its weight.

A worked example

A 10 × 10 ft area at 4 inches deep needs about 33.33 cubic feet before allowance. With 10% extra, that is 36.67 cubic feet or 1.36 cubic yards. At a stated yield of 0.6 cubic feet per bag, round up to 62 bags.

Volume does not design a slab

This calculator does not select depth, mix strength, reinforcement, base preparation or load capacity. Obtain appropriate project specifications before buying. For uneven ground or multiple sections, measure and calculate those sections separately.