How to use the converter
- Pick your material from the list.
- Type a weight in tonnes, or a volume in cubic metres. The other box fills in for you.
- Read the bulk bag count and the range underneath. Ask your supplier to confirm their density before you order.
- Press + Add to shopping list if you want to keep the figure with the rest of your materials.
Why use this converter
Aggregates are sold by the tonne but spread by the cubic metre. A path needs a volume. A merchant wants a weight. This tool turns one into the other.
We use density figures from UK suppliers and show the source for each one, so you can check them. Real loads vary with moisture and compaction, so we also show a range.
Densities we use
Every figure below comes from UK supplier pages. Tonnes per cubic metre, as the material is normally delivered.
| Material | Tonnes per m³ | Range | m³ per tonne |
|---|---|---|---|
| Gravel (10–20 mm) loose, as delivered | 1.7 | 1.6–1.8 | 0.59 |
| Pea shingle loose, as delivered | 1.6 | 1.55–1.7 | 0.63 |
| Slate chippings loose, as delivered | 1.6 | 1.45–1.6 | 0.63 |
| MOT Type 1 (loose) loose, as delivered | 2 | 1.9–2.2 | 0.5 |
| MOT Type 1 (compacted) compacted, in place | 2.1 | 2–2.2 | 0.48 |
| Sharp sand loose, as delivered | 1.7 | 1.5–1.8 | 0.59 |
| Building sand loose, as delivered | 1.6 | 1.5–1.7 | 0.63 |
| Ballast (all-in) loose, as delivered | 1.8 | 1.6–1.8 | 0.56 |
| Topsoil loose, screened, as delivered | 1.5 | 1.3–1.5 | 0.67 |
| Compost loose | 0.5 | 0.35–0.8 | 2 |
| Bark mulch | 0.35 | 0.33–0.4 | 2.86 |
| Crushed concrete loose, as delivered | 1.6 | 1.6–2 | 0.63 |
| Concrete (set) | 2.4 | 2.3–2.4 | 0.42 |
Figures checked 2026-11-06. Densities move with moisture, so treat them as a guide.
Tips
- Loose material takes more room than compacted material. MOT Type 1 shrinks as it is rolled, so order extra for a sub-base.
- Wet sand and soil weigh more than dry. If it is raining, the tonnes on your ticket may be higher than the table suggests.
- A bulk bag is about 850 kg, but the volume depends on the material. Heavy stone fills it less than light bark or compost.
- Add 5 to 10% for waste and uneven ground before you order.
FAQs
How many cubic metres are in a tonne?
It depends on the material. One tonne of gravel is about 0.59 m³. One tonne of topsoil is about 0.67 m³. Pick the material above for an exact answer.
Why does the answer change with the material?
Different materials have different densities. A cubic metre of gravel weighs about 1.7 tonnes. A cubic metre of bark weighs about 0.35 tonnes.
How many tonnes of gravel do I need?
Work out the volume first: area × depth. Then type that in the cubic metres box. For a driveway, our gravel calculator does the volume for you.
What is the difference between loose and compacted?
Loose is how the material arrives on the lorry. Compacted is after it has been rolled or rammed. Compacted material is denser, so the same weight takes less space.
How many bulk bags is that?
A bulk bag holds about 850 kg. We divide your weight by that and round up. Retail bags vary, from about 600 kg to a tonne, so check the label.