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Gravel calculator

Estimate loose or compacted gravel volume, mass, bags and material cost. See clear formulas, worked examples, assumptions and a printable estimate.

Gravel Calculator

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Coverage areas

Use non-overlapping areas. All areas use the same material and layer thickness.

Layer & material

Enter a supplier-confirmed correction. 20% means 1.20 units of loose volume for 1 unit of compacted volume; it does not mean 20% volume loss. Allowance is added afterward.

The starting density is an example, not a verified value for your gravel. Replace it with the supplier’s loose bulk density. Density varies with product and condition. No compaction correction is assumed automatically.

Purchase & prices

Use the net material mass on the label. Whole bags are rounded up.

Prices are editable examples. Currency changes the label only. Bulk quantities are not rounded to supplier minimums or truckloads.

How to useCalculation methodRead the project guide

How to use

  1. Add rectangular, circular or known-area zones using the same gravel product and layer thickness.
  2. Choose whether the depth describes a loose layer or a finished compacted layer. For compacted depth, enter the additional loose-volume percentage.
  3. Enter the loose bulk density supplied for your material, then choose bulk pricing by mass or volume, or bags by net mass.
  4. Set your allowance and review geometric volume, loose order volume, mass and material cost.

Calculation method

Geometric volume = total area × depth. For a compacted layer, loose volume = geometric volume × (1 + entered compaction addition / 100); for a loose layer these volumes are equal. Apply the allowance to that loose volume. Mass = loose volume with allowance × entered loose bulk density. Bags round mass up to whole bag weights. Bulk cost uses purchased mass or volume; bag cost uses complete bags.

Worked example

For 4 × 3 m at 5 cm loose depth, net volume is 0.6 m³. A 10% allowance gives 0.66 m³. At 1600 kg/m³ that is 1056 kg, or 1.056 metric tonnes; at 50 USD/tonne it costs 52.80 USD. Bags of 25 kg require 43 bags, or 215 USD at 5 USD each. A compacted depth with a chosen +20% loose-volume addition gives 0.792 m³ after allowance and 63.36 USD at the same density and bulk price.

Assumptions and limits

Density and compaction additions are material- and project-specific. The starting density is an editable example. A metric tonne is 1000 kg; a US short ton is 2000 lb and must not be treated as the same unit. This tool does not design drainage, base layers or load-bearing systems. Bulk orders are not rounded to truckloads or supplier minimums. Delivery, machinery, labor and tax are excluded.

Units, prices and saved estimates

Physical values are stored internally in metres, square metres, cubic metres or kilograms as appropriate. Changing measurement units converts their display; choosing a currency changes its label without applying an exchange rate. Purchase quantities use unrounded calculations. Money is shown to two decimal places.

Edits can be saved in this tab. Optional device saving lasts seven days after the last save. Copy, TXT download and a separate printable report use the current valid estimate. Delete draft removes saved inputs without resetting the visible form. The privacy choices page can remove all calculator drafts.

For practical measurement decisions, read checking gravel depth, density and compaction.