Chain of evidence
Tonnes to cubic metres – and the densities behind it
Suppliers deliver in tonnes, but you plan in cubic metres. The converter here works both ways – using exactly the densities listed in the table below, each with its source, retrieval date, verification status and evidence class. Where the sources contradict each other, you get a range instead of an invented decimal. Where no documented value exists, it says so – rather than showing a zero.
A note on scope: the densities, gradings such as 0/32 and the bag and bulk-bag sizes used here follow German trade practice, and all sources are German suppliers and trade portals. The physics is the same everywhere, but the products your local supplier sells may be graded and packaged differently. All units are metric.
Convert tonnes and cubic metres
Suppliers deliver in tonnes, planning happens in cubic metres. Both directions, always as a range – because the density is one.
The finding this calculator is built on
For bark mulch the supplier kiesdirekt.de quotes 0.31 t/m³, while a widely used online calculator quotes 0.90 t/m³ – roughly three times as much. Order by the higher figure and 10 m³ becomes about 9 t instead of 3.1 t. The cross-check via bag data (70 l weighing 17.5 to over 30 kg, i.e. 0.25–0.43 t/m³) confirms the supplier.
That is why this calculator gives no weight at all for bark mulch, compost and wood chips: schuettgut-kleintransporte.de states explicitly that these materials are traded by volume only, because their weight varies with moisture. A figure in tonnes would be a number the trade does not use.
| Material | Grading | Density t/m³ | Source |
|---|---|---|---|
| Bark mulch | 0/60 | 0.31 · sold by volume only | Q3 |
| Compost | — | sold by volume only | Q2 |
| Wood chips | — | sold by volume only | Q2 |
| Gravel | 2/8 | 1.5 – 1.6 | Q2, Q1 |
| Gravel | 8/16, 16/32 | 1.6 – 1.7 | Q1, Q2 |
| Concrete gravel | 0/16, 0/32 | 1.7 | Q1, Q2 |
| Screed gravel | 0/8 | 1.7 | Q2 |
| Chippings | 1/3, 2/5 | 1.5 – 1.6 | Q1, Q2 |
| Chippings | 8/11 | 1.5 – 1.7 | Q1, Q2 |
| Lava rock | 2/8, 16/32, 0/45 | 1.4 | Q2 |
| Crushed stone | 0/32, 16/32, 32/56 | 1.6 – 1.7 | Q1, Q2 |
| Crushed aggregate base | 0/32 | 1.7 | Q1 |
| Sand | 0/2 | 1.4 – 1.5 | Q1, Q2 |
| Sand | 0/5 | 1.7 | Q2 |
| Recycled sand | 0/5 | 1.6 | Q2 |
| Topsoil | — | 1.4 – 1.5 | Q2, Q1 |
| Topsoil substrate | — | 1.2 | Q2 |
| Lawn substrate | — | 0.77 | Q2 |
| Potting and planting compost | — | sold by volume only | — |
- Q1anzugsmoment.de — Class C, secondary source · unverified · 2026-08-19. Weight of gravel, chippings, crushed stone and sand. One table per material without grading; the page itself states that all figures are without guarantee. Open source
- Q2schuettgut-kleintransporte.de — Class B, direct market observation · documented · 2026-08-19. A supplier's aggregate calculator with densities by grading. States explicitly that wood chips, compost and bark mulch are traded by volume only. Open source
- Q3kiesdirekt.de — Class B, direct market observation · documented · 2026-08-19. Quantity calculator for bark mulch 0–60 mm. Quotes 0.31 t/m³ and additionally shows the weight with 15 % compaction. Open source
- Q4gartenjournal.net — Class C, secondary source · unverified · 2026-08-19. Bark mulch: weight and quantity. Bulk density 0.25–0.40 t/m³ and layer depths. Seen only as a search result, the page itself was not retrieved.
- Q5selbst.de, bau-szene.de, berdingbeton.de — Class C, secondary source · unverified · 2026-08-19. Paving trade portals, layer depths for frost protection, base course and bedding. The binding rules would be ZTV Wegebau, the FGSV code and DIN 18318 – paid documents, not retrieved for this edition. Load-bearing or trafficked surfaces belong in professional hands.
- Q6samen.de, moowy.de, rasen1.com — Class C, secondary source · unverified · 2026-08-19. Lawn trade portals, seed rates per m². The relevant German Turfgrass Society was not consulted.
- Q7isteshaltbar.de, bau-szene.de — Class C, secondary source · unverified · 2026-08-19. Concrete trade portals, yield 12–13 l of fresh concrete per 25 kg bag, fresh concrete 2.2–2.4 t/m³.
- Q8plantura.garden, obi.de, hornbach.de — Class C, secondary source · unverified · 2026-08-19. Raised bed trade portals, four-layer build-up, 10–30 cm per layer depending on bed height.
- DRule of thumb, no source — Class D, estimate or rule of thumb. Experience from garden practice for which no reliable source was available in this edition. It is marked as such in the result and is not presented as a documented fact.
Data set as of 19 August 2026. Densities are material properties and age slowly – review every six months: after 210 days a visible warning appears here, after 400 days the data set is no longer published at all. Prices, delivery charges and individual suppliers' bag sizes are deliberately absent, because they age faster than this calculator can be maintained. What is binding is always your supplier's figure for the actual batch.