How we calculate

Every HowManyYards result comes from the same simple geometry the trade uses. There is no black box: the formulas and the constants are below, so you can check any answer by hand.

The formulas

Volume (cubic feet)area (sq ft) x depth (in) / 12
Cubic yardscubic feet / 27
Bags neededcubic feet / cubic feet per bag, rounded up
Estimated weightcubic yards x weight per cubic yard

The constants

1 cubic yard27 cubic feet (definition)
Mulch bag2 cubic feet (industry standard)
Concrete - 80 lb bag0.60 cubic feet yield
Concrete - 60 lb bag0.45 cubic feet yield
Concrete - 50 lb bag0.375 cubic feet yield
Concrete - 40 lb bag0.30 cubic feet yield
Gravel weightabout 1.25 to 1.7 tons per cubic yard
Sand weightabout 1.1 to 1.45 tons per cubic yard
Topsoil weightabout 1.0 to 1.35 tons per cubic yard

Why weights are ranges

Loose materials like gravel, sand, and topsoil do not have a single fixed weight. The figure changes with stone size, composition, and especially moisture - wet sand can weigh noticeably more than dry. Rather than invent false precision, we calculate weight from a sensible midpoint and tell you the range, so you can order with a margin. Always round up and allow a little extra for settling and waste.

Sources

Our constants come from published, checkable references rather than guesswork:

Maintained and reviewed by the HowManyYards team. We recheck our formulas and constants periodically and welcome corrections at hello@howmanyyards.com.

Last reviewed: June 2026

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