Cubic metres to tonnes: sand, gravel, concrete and soil

To convert cubic metres to tonnes, multiply the volume by the density of the material. Eurocode EN 1991-1-1 gives 14 to 19 kN/m³ for stored sand, which is 1.43 to 1.94 tonnes per m³: the weight depends on the actual material, not just the volume.

From cubic metres to tonnes: volume × density

A volume cannot be turned into a weight without knowing what it is made of. The formula is always the same: weight in tonnes = volume in m³ × density in tonnes per m³. The other way round, volume = weight ÷ density.

Eurocode 1 (EN 1991-1-1, Annex A), published in the UK as BS EN 1991-1-1, is the European reference for these values. It gives them as unit weights in kilonewtons per m³: divide by 9.81, the acceleration due to gravity, to get tonnes per m³. Normal-weight concrete at 24 kN/m³ therefore weighs 24 ÷ 9.81 = 2.45 tonnes per m³.

Cubic metres to tonnes conversion table

Unit weights from Eurocode EN 1991-1-1 (Annex A), divided by 9.81 to go from kN/m³ to tonnes per m³. Example: 5 m³ of stored sand weighs 7.1 to 9.7 tonnes; the Eurocode gives a range, not a single figure. Soil is not listed.

Why a range rather than one figure

For concrete, cement and lime the Eurocode gives a single value. For aggregates it gives a range: stored sand runs from 14 to 19 kN/m³, which is 1.43 to 1.94 tonnes per m³. The calculator shows the whole range rather than an average that no standard gives.

For an order, the exact figure comes from your supplier: ask the quarry or builders' merchant for the density of their sand. Otherwise, weigh a 10-litre bucket filled level: 15 kg in 10 litres is 1.5 tonnes per m³.

Worked examples

• 6 m³ of stored sand: 6 × 1.43 to 6 × 1.94, so 8.56 to 11.62 tonnes.
• 10 tonnes of sand delivered: 10 ÷ 1.94 to 10 ÷ 1.43, so 5.16 to 7.01 m³ to store.
• 3 tonnes of loose gravel (15 to 16 kN/m³): 1.84 to 1.96 m³.
• An 8 m³ mixer load of wet concrete (25 kN/m³): 8 × 2.55 = 20.39 tonnes.
• A 20 m² path with 5 cm of gravel: 20 × 0.05 = 1 m³, so 1.53 to 1.63 tonnes of loose gravel.
• Hardcore under a 12 m³ slab base (18.5 to 19.5 kN/m³): 22.63 to 23.85 tonnes.

Soil and Type 1: enter your own density

Annex A of the Eurocode has no figure for topsoil, subsoil or building rubble, and we have not found a reliable public source that does. MOT Type 1 sub-base has no line of its own either. So the calculator offers no default for these: enter the figure from your groundworker or supplier, or weigh a bucket.

Excavated soil takes up more room than it did in the ground; this is called bulking. How much depends on the soil and on how it is loaded, so ask whoever is taking it away. For sand and gravel, the Eurocode has its own line for gravel and sand, bulked, at 15 to 20 kN/m³, which is 1.53 to 2.04 tonnes per m³.

Common mistakes

• Reading kN/m³ as tonnes: 19 kN/m³ is not 19 tonnes per m³ but 1.94 tonnes.
• Using a single standard figure for sand: between the two limits in the Eurocode, 6 m³ varies by more than 3 tonnes.
• Forgetting that excavated soil bulks up when ordering skips or grab lorries.
• Confusing wet and hardened concrete: wet concrete adds 1 kN/m³, and reinforcement another 1.

To find the volume to convert, the area calculator helps with gravel or screed per m², the pool volume calculator gives the spoil from digging a pool, and the slope calculator sets the fall of a drive or patio base.