Formula used
Rectangular area: A = L × W. Circular area: A = πr². Semicircular area: A = ½πr².
Layer volume: V = A × D. Adjusted volume: Vₐ = V × C × (1 + W ÷ 100). Weight: M = Vₐ × ρ.
Bags: N = ceiling(M ÷ bag weight). Purchase quantities always round upward to complete supplier units.
How to use this calculator
Choose the path shape and enter its measurements. Subtract any drains, steps, or planting pockets. Confirm every measurement uses the selected unit before calculating.
Select the surface material and set each construction depth. Adjust density, compaction, and waste for supplier conditions. Use realistic layer depths recommended for your expected traffic.
Enter packaging, edging, membrane, excavation, and price information. The result separates calculated quantities from rounded purchase quantities. Review supplier specifications before ordering or starting excavation work.
Example garden path estimate
| Input | Example value | Purpose |
|---|---|---|
| Length and width | 12 m × 1.2 m | Calculates 14.4 m² path area |
| Surface depth | 50 mm | Defines decorative material volume |
| Sub-base depth | 100 mm | Supports a stable pedestrian path |
| Waste allowance | 10% | Covers spills, cuts, and minor measurement differences |
| Compaction factor | 1.15 | Allows extra loose aggregate before compaction |
Material and installation guidance
Gravel paths need firm edges and a compacted base. Fine material can migrate without proper edge restraint. Install membrane where soil separation improves long-term path stability.
Pavers require accurate levels, consistent joints, and suitable bedding. Herringbone patterns usually create more cuts near boundaries. Order full packs when suppliers prohibit individual unit purchases.
Excavated soil expands after removal from the ground. Disposal volume can exceed the original trench volume significantly. Check local access before arranging skips or delivery vehicles.
Frequently asked questions
How deep should gravel be?
Many pedestrian paths use about 40 to 60 millimetres. Softer ground may need a deeper structural base. Confirm depth with material and site conditions first.
Why does the calculator use compaction?
Loose aggregate occupies more volume before it is compacted. Compaction reduces voids and improves structural stability. The factor adds material needed before final compaction occurs.
Should waste apply to every layer?
Waste commonly affects loose materials, pavers, and membrane coverage. Each supplier package may require different rounding. Adjust the percentage for difficult cuts or handling.
How are paver joints included?
The calculator adds joint width to each paver module. Wider joints reduce the number of pavers required. Pattern and waste factors then increase the purchase quantity.
What density should I enter?
Use the supplier bulk density for your exact material. Moisture and grading can change actual delivered weight. Supplier data usually gives the most reliable conversion.
How is edging length calculated?
Rectangular paths can use one or both long sides. Ends can be included using the provided checkbox. Other shapes use half or all calculated perimeter.
Why is excavation volume larger after removal?
Soil loosens and expands when removed from place. The expansion factor estimates this additional disposal volume. Different soils require different bulking factors for accuracy.
Can I calculate only stepping stones?
Choose the stepping-stone shape and enter stone dimensions. The calculated area covers only the individual stones. Add surrounding aggregate separately using another calculation run.
Does the total include VAT?
The total uses your entered tax or VAT percentage. Set the percentage to zero when tax is excluded. Always confirm whether supplier prices already include tax.
Why are bags and packs rounded upward?
Suppliers normally sell complete bags, packs, or rolls. Fractions cannot usually be purchased as separate quantities. Upward rounding prevents material shortages during installation work.
Are results suitable for structural design?
The calculator provides planning and purchasing estimates only. Ground conditions and loads may require professional design. Seek qualified advice for vehicles or unstable ground.