How much material does your garden need?

Between 1.5 and 1.7 tonnes depending on grading. Gravel 2/8 sits at 1.5–1.6 t/m³, gravel 8/16 and 16/32 at 1.6–1.7 t/m³. That difference of roughly 13 % comes from the grading alone – which is why it is an input field here. Your supplier's figure for the actual batch remains binding.

Because bark mulch, compost and wood chips are sold by volume only. Their weight varies so much with moisture that a figure in tonnes says nothing. Calculators that still quote tonnes sometimes use 0.90 t/m³ – roughly three times the supplier's 0.31 t/m³.

For a decorative gravel area 4–5 cm is enough; walkable paths usually get 5–8 cm. Bark mulch sits at 3–5 cm in a perennial bed and 7–8 cm where it is meant to suppress weeds. These values come from trade portals and are marked unverified.

Tonnes divided by the density in t/m³ gives cubic metres. With gravel 8/16 at 1.6–1.7 t/m³, 5 tonnes is 2.9 to 3.1 m³. Because the density is a range, the result is a range too – anyone quoting a single figure is only pretending to be more precise.

Around 15 % for frost protection and base layers, because the material loses volume when compacted. For loose decorative areas 5–10 % is enough to cover unevenness and losses while tipping. The chipping bedding gets no allowance.

Usually not. A cubic metre of gravel weighs 1.5 to 1.7 tonnes, while a 750 kg trailer often carries only around 500 kg net. That is why the calculator also shows the number of loads needed at a 500 kg payload.

No. They are planning aids based on publicly available density figures and replace neither your supplier's data nor professional design work. For load-bearing or trafficked surfaces the binding rules are ZTV Wegebau, the FGSV code and DIN 18318; those paid documents were not evaluated.