Aggregate Tonnage Calculator

Calculate tonnes of gravel, road base or aggregate needed for an area at a given depth.

Tonnes = area (m²) × depth (m) × density (t/m³). 50 m² at 100 mm using 1.6 t/m³ road base needs 8.0 tonnes.

Calculator

Area to cover (m²)Compacted depth (mm)Material density (t/m³)Road base ≈ 1.6–2.2 t/m³; gravel ≈ 1.5–1.7 t/m³.

Aggregate required

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How it works

Work out the volume (area × depth) then multiply by the material's bulk density to get weight, since suppliers sell aggregate by the tonne. Use the compacted depth and the supplier's density figure for the best estimate.

Worked example

50 m² × 0.10 m = 5 m³, × 1.6 t/m³ = 8.0 tonnes. For a 150 mm depth it would be 12.0 tonnes.

Assumptions & limitations

Density varies by material, moisture and compaction — ask your supplier for the figure for the exact product. Allowing for compaction, order the depth you want after compacting, plus a small waste margin.

Frequently asked questions

What density should I use for road base?

Compacted road base is commonly around 2.0–2.2 t/m³, while loose gravel is nearer 1.5–1.7 t/m³. Use the figure on your supplier's data sheet for the specific product — it's the biggest source of error.

Loose or compacted depth?

Enter the finished, compacted depth you want. Material compacts as it's rolled, so you'll spread it deeper; ordering by compacted depth plus a small margin avoids running short.

How do I convert tonnes to cubic metres?

Divide tonnes by the density. 8 tonnes ÷ 1.6 t/m³ = 5 m³. Suppliers quote tonnes, so this calculator gives you the order weight directly.

Last updated 21 June 2026

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