Terms of use

By using this site you agree to these terms.

Results are estimates for planning

The calculators turn the values you enter into quantities and, where you supply the data, estimated weights and costs. Results depend on your inputs. Weights and costs are estimates, because real materials, conditions and prices vary. Confirm quantities and prices with your supplier before ordering.

Not professional advice

The site does not design driveways, drainage, paver bases, erosion protection or any other structure, and it is not a substitute for advice from a qualified professional who knows your site.

Sources

External sources are cited for context and conversion factors, as described on our Sources page. They are the work of their publishers.

Changes

We may update the calculators and these terms. Each calculator page shows the date its content was last reviewed.