Road Base Calculator

Road base for driveways, paver bases and slabs: tonnes and m³ (or tons and cubic yards) for your area, with extra for compaction built in.

Road base is crushed rock graded from about 20 mm down to fine dust, so it compacts into a firm, stable layer. In Australia it's the usual base under pavers, concrete slabs, driveways and shed floors, and in Victoria it's often sold as fine crushed rock (FCR). Suppliers sell it by the tonne or by the cubic metre. Enter the area and the compacted depth and this calculator gives the tonnes and m³ (or tons and cubic yards), with 20% extra for compaction by default, and the bags if you only need a little.

Units
Bag sizes
Area
ft
ft
in
Feet and inches work too: type 12'6 or 12.5.
t/yd³
%
A compacted base: the extra covers compaction.
Weight
2.54 tons

5,084 lb · 2.31 tonnes

Volume
1.78 yd³

48 ft³ · 1.359 m³

How it was worked out
  1. Area: 12 ft × 10 ft = 120 ft²; × 4 in (0.333 ft) deep = 40 ft³
  2. 40 ft³ ÷ 27 = 1.48 yd³
  3. Plus 20% extra = 1.78 yd³
  4. 1.78 yd³ × 1.43 tons per yd³ = 2.54 tons (5,084 lb)
Typical weights of common materials
Materialt/m³tons/yd³lb/ft³
Concrete2.402.02150
Gravel1.601.35100
Pea gravel1.601.35100
Crushed stone / crushed rock1.601.35100
River rock1.501.2694
Landscape rock / pebbles1.501.2694
Crushed limestone1.601.35100
Decomposed granite1.501.2694
Crusher run1.601.35100
Road base1.701.43106
Crusher dust1.501.2694
Aggregate (20 mm)1.601.35100
All-in ballast1.651.39103
MOT Type 1 sub-base1.801.52112
Sand1.601.35100
Topsoil1.301.1081
Garden soil1.301.1081
Fill dirt1.401.1887
Mulch0.350.2922
Bark chippings0.300.2519
Asphalt (compacted)2.321.96145

Loose, as-delivered figures; asphalt and concrete are as laid. Moisture, stone size and source change the real weight, so use your supplier's figure when you have it. Tons are US short tons (2,000 lb).

Common use cases

  • A base under a paver patio, path or driveway
  • Levelling and preparing ground for a concrete slab or shed
  • Building up a gravel driveway or farm track
  • Ordering by the tonne or the cubic metre

How to use

  1. Choose feet and inches or metres and millimetres, and the country whose bag sizes you want.
  2. Enter the length and width of the area, or switch the shape to a circle, triangle or a known area. Use Add another area for L-shapes and separate beds.
  3. Enter the depth of road base. Enter the compacted depth: often 75 to 100 mm for paths and patios and 100 to 150 mm or more for driveways.
  4. Check the density and the extra allowance. Change the density if your supplier quotes a different figure.
  5. Read the volume, weight and bag count, and add a price per ton, cubic yard, m³ or bag for a cost estimate.

FAQ

How much does road base weigh?

About 1.6 to 1.8 tonnes per m³ loose; compacted it can be over 2 tonnes per m³. The calculator uses 1.7 tonnes per m³ loose and adds 20% for compaction.

Should I order by the tonne or by the cubic metre?

Whichever your supplier prices in. The calculator shows both. If a quote is per cubic metre, check whether that's loose or compacted, as it makes a big difference.

How deep should road base be under pavers?

Commonly 75 to 100 mm compacted for foot traffic and more for driveways, topped with a thin bedding layer of sand or crusher dust. Poor or clay soils may need more.

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