How the calculations work
All tools share one calculation library. The library converts length to meters, volume to cubic meters and mass to kilograms. It rounds results for display, and rounds bag and paver counts up to whole units.
Rectangle area = length × width. Circle area = π × (diameter ÷ 2)². Combined area = included areas − exclusions. For different depths, add each section’s area × depth and subtract exclusions at their stated depth, then apply the allowance once. A blank section depth uses the main depth. Volume = net section volume × (1 + allowance ÷ 100).
Weight = volume × your supplier’s density. One US short ton is 2,000 pounds, one imperial long ton is 2,240 pounds, and one metric tonne is 1,000 kilograms.
Paver coverage uses (length + joint) × (width + joint). This treats each paver and its joint as a rectangle. It does not account for edge joints or cuts. Paver waste and the allowance for base or bedding volume are separate inputs. Pack counts use the supplier’s coverage and round upward.
You enter the depths, blend proportions, density, prices and allowances. Material calculators price the main material. UK project planners price each specified material independently and label partial totals when prices or weight conversions are missing. Each quote includes its own delivery input; allocate a delivery shared between materials once. Labour and other installation costs are excluded.
Sources & what they cover
- NIST SI conversion factorsNational Institute of Standards and Technology
Exact US customary and SI conversion factors; no material or installation recommendations.
Source checked
We check what each reference covers. A source check does not mean a specialist has reviewed this tool. You supply the depths, densities, prices and blend proportions.
Calculation checks
Automated tests check rectangle and circle volume, allowance, full-bag rounding, blends, paving counts and equivalent metric inputs. Browser checks exercise gravel, raised-bed and paving flows. These checks cover the listed calculations and flows. They do not assess material choices or construction designs.