Crusher Dust Calculator

Crusher dust for paver bedding and fine bases: tonnes and m³ for your area at 30–50 mm deep, with 20 kg bags or bulk tonnes counted.

Crusher dust is the fine material left from crushing rock, from dust up to a few millimetres. Compacted, it makes a smooth, firm bedding layer under pavers and flagstones, a base under above-ground pools and water tanks, and pipe bedding. It's sold in 20 kg bags at hardware stores and by the tonne or cubic metre from landscape suppliers. Enter the area and depth and this calculator gives the tonnes and m³ (or tons and cubic yards), with 15% extra for compaction, and the number of bags.

Units
Bag sizes
Area
m
m
mm
t/m³
%
Usually laid 30–50 mm thick as bedding under pavers.
Weight
1.04 tonnes

1,035 kg · 1.14 US tons

Volume
0.69 m³

690 L · 0.9 yd³

Bags
52

20 kg bag

Bags needed by size
20 kg bag52
1 tonne bulk bag2
How it was worked out
  1. Area: 4 m × 3 m = 12 m²; × 50 mm (0.05 m) deep = 0.6 m³
  2. Plus 15% extra = 0.69 m³
  3. 0.69 m³ × 1.5 t/m³ = 1.04 tonnes (1,035 kg)
  4. 1,035 kg ÷ 20 kg per bag = 51.75, rounded up to 52 bags
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

  • Bedding under pavers or flagstones
  • A level base for an above-ground pool or rainwater tank
  • Bedding and backfill around pipes
  • Filling joints and gaps in a crushed-rock path

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 crusher dust. A bedding layer under pavers is usually 30 to 50 mm, over a compacted road base.
  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 crusher dust do I need under pavers?

Multiply the area by the bedding depth. 20 m² at 40 mm is 0.8 m³, about 1.4 tonnes at 1.5 tonnes per m³ with 15% extra. The road base underneath is a separate layer.

How many 20 kg bags of crusher dust in a cubic metre?

At about 1.5 tonnes per m³ loose, a cubic metre is about 75 × 20 kg bags. For more than a few square metres, a bulk delivery is usually cheaper.

Crusher dust or sand under pavers?

Both are used. Crusher dust compacts firmer and resists washing out; washed paving sand is easier to screed and drains better. Follow your paver supplier's recommendation.

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