Understanding Tonnage Calculation
The Tonnage Calculator determines the weight of bulk material required for a given area. This is essential because most aggregates, soil, and gravel are sold and delivered by weight (Tons or tonnes), not volume (m³ or yd³).
Core Calculation Principle
The formula relies on two variables: Volume and Density (specifically, Bulk Density).
- Volume: Length × Width × Thickness (must use consistent units).
- Weight (Tonnage) = Volume × Bulk Density.
- Bulk Density is the weight of the material per unit volume including the air voids, which is critical for loose materials like gravel or soil.
Why is a Waste Factor Used? (15%)
A waste factor is added to ensure you order enough material. Reasons include:
| Factor | Impact |
|---|---|
| Site Loss | Spillage during transport, dumping, and spreading. |
| Sub-base Irregularities | Uneven ground requires more material to achieve uniform thickness. |
| Settling/Compaction | Material will settle slightly after initial placement (especially soil/gravel). |
A standard 10% to 15% waste factor is recommended for most bulk landscape and construction materials.