PRACTICAL HOME PROJECT MATH
Mulch & gravel calculator
Convert a rectangular bed’s measurements into cubic yards and bags.
YOUR PLANNING ESTIMATE
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Enter your measurements
See the calculation
The calculation
Multiply length and width in feet by depth in inches divided by 12. Apply your allowance for extra material. Divide cubic feet by 27 for cubic yards, or by bag volume for bags.
A worked example
A 10 × 10 ft bed at 3 inches deep needs 25 cubic feet before allowance. With 10% extra, that is 27.5 cubic feet, about 1.02 cubic yards, or 14 bags holding 2 cubic feet each.
Volume is not weight
Gravel density and moisture affect tonnage. Ask the supplier to convert your volume for the actual product. Depth is an input, not a recommendation. Split irregular beds into rectangles and add their volumes.