Cubic Metres to Tonnes Calculator

Convert volumetric delivery specifications (m³) into legal weighbridge mass in metric tonnes (t) and kilograms (kg). Calibrated to SABS 1200 construction material densities.

Volume (m³)

Select Material Density

Total Estimated Weighbridge Mass

24.00metric tonnes

Equivalent to: 24,000 kg (26.46 US short tons)

SABS & ISO Material Density Quick-Reference Table

Standard bulk densities and recommended compaction factors across common South African construction materials.

Material Classification	Density (kg/m³)	Tonnage (t/m³)	Standard Waste	Standard Spec
Concrete (Standard Reinforced / Ready-Mix)	2 400	2.40	+10%	SANS 1200 G / SANS 878
Concrete (Plain / Unreinforced)	2 300	2.30	+8%	SANS 1200 G
Gravel / Crushed Stone (19mm / G5 Subbase)	1 680	1.68	+12%	SANS 1200 M / SANS 1083
Building Sand (Clean River / Plaster Sand)	1 600	1.60	+10%	SANS 1090
Topsoil (Screened Loam / Garden Soil)	1 250	1.25	+15%	General Landscaping Spec
Garden Mulch / Pine Bark	650	0.65	+10%	Horticultural Spec
Asphalt (Hot-Mix Premix)	2 350	2.35	+8%	SANS 1200 MH
Clay Soil (Compacted Fill)	1 800	1.80	+15%	SANS 1200 D

Density Calculation Rule: 1 cubic metre (1 m³) of water weighs exactly 1,000 kg (1.0 tonne). To calculate mass in metric tonnes, multiply the gross volume in m³ by the material's specific gravity (t/m³).

Mathematical Formula for Volume to Mass Conversions

The engineering mathematics behind volumetric measurement, compaction allowances, and ready-mix batching.

Normalize to Metres (m)

Slab thickness and trench depths are commonly specified in millimetres (e.g., 150 mm) or centimetres (15 cm). Convert all dimensions to metres before multiplying:

Depth (m) = mm ÷ 1,000
150 mm ÷ 1,000 = 0.150 m

Solve Net Volume (m³)

Multiply length by width and depth to determine the net physical void space. For cylinders (round tanks, circular slabs), multiply base area ($\pi r^2$) by height:

V_net = L × W × D
10.0 m × 5.0 m × 0.15 m = 7.50 m³

Apply Compaction & Waste

Excavated subgrades settle, formwork flexes under hydraulic pressure, and pumps retain residual mix. Always factor 5% to 15% extra for realistic batching:

V_order = V_net × (1 + Waste %)
7.50 m³ × 1.10 (+10%) = 8.25 m³

Density & Weighbridge FAQs

Common questions regarding metric cubic metre calculations, bulk densities, and material batching.

How do you convert cubic metres to metric tonnes?

Multiply the volume in cubic metres by the material bulk density in tonnes per cubic metre: Mass (t) = Volume (m³) × Density (t/m³). For example, 10 m³ of gravel with a density of 1.68 t/m³ weighs: 10 × 1.68 = 16.8 metric tonnes.

How much does 1 m³ of water weigh?

At standard temperature and pressure (4°C), exactly 1 cubic metre of pure water weighs 1.00 metric tonne (1,000 kg). This serves as the benchmark specific gravity (SG = 1.0) for all other material densities.

Why does aggregate density vary between loose and compacted states?

Dry loose aggregate contains air voids between particles. When rolled or mechanically vibrated, the void ratio decreases, increasing the compacted bulk density by 10% to 15% and requiring more material weight per finished cubic metre.