About this tool Estimate fill material quantities for earthworks and construction. Select from 11 common UK fill materials — including Type 1 sub-base (MOT), 6F2 capping, gravel, sand, topsoil, crushed concrete, chalk, clay, and pea gravel — each with industry-standard compacted densities and bulk factors.
The calculator converts between compacted (in-place) volume and loose (as-delivered) volume using material-specific bulk factors. This is critical for ordering: if you need 100 m³ of compacted fill, you must order more than 100 m³ of loose material to account for the volume increase during excavation and transport.
Results include compacted and loose volumes, total weight in tonnes, and an estimate of 20-tonne lorry loads for delivery planning. Three area shapes are supported: rectangular, trapezoidal (for battered trenches and cuttings), and circular.
How to use this tool 1. Select the material — choose the fill type from the dropdown. Each material has a specific compacted density and bulk factor shown in the reference table.
2. Choose the area shape — rectangular for general fills and platforms, trapezoidal for trenches with battered sides, or circular for soakaways and pits.
3. Enter dimensions in metres — provide length, width(s), and layer depth/thickness. For trapezoidal trenches, enter both top and bottom widths.
4. Read the results — use the loose volume (order quantity) when placing orders with your supplier, and the weight/lorry loads figure for delivery planning.
Technical information The bulk factor (or swell factor) accounts for the increase in volume when material is excavated or transported loose compared to its compacted in-place volume. For example, a bulk factor of 1.25 means you need to order 25% more loose material than the compacted volume you require.
Loose volume = compacted volume × bulk factor
Rectangular: V = length × width × depth
Trapezoidal: V = ((top width + bottom width) / 2) × depth × length
Circular: V = π × (d/2)² × depth
Always order the loose volume to achieve the required compacted fill. Actual bulk factors vary with source, grading, moisture content, and placement method.
Delivery estimates Lorry load estimates are based on a standard 8-wheel (8×4) rigid tipper with a 20-tonne payload on a 32-tonne GVW chassis. Actual payload varies by vehicle type and road restrictions. For large orders, confirm capacity with your supplier.
Limitations Densities and bulk factors are approximate industry values. Actual properties vary significantly with source quarry, grading, moisture content, and degree of compaction. Always confirm material properties with your supplier for critical quantities.
The calculator assumes uniform layer thickness across the entire area. For variable-depth fills or complex site profiles, break the area into zones and calculate each separately.
Lorry load estimates do not account for access restrictions, tipping time, or site-specific vehicle limitations. Check with your haulier for maximum payload on your route.
Revision history 9 April 2026: Initial release
Disclaimer This tool is provided for educational and general information purposes only. It is not a substitute for professional engineering advice, design or verification.
Diggy and its contributors are not licensed engineering consultants and no results generated by this tool should be used directly for construction, design or safety-critical decisions.
All values and outputs are based on published empirical correlations and should be independently checked and confirmed by a qualified geotechnical engineer before use.
By using this tool, you accept full responsibility for how you interpret and apply the information provided.
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