Calculator inputs
Example projects
| Project | Footprint | Depth | Allowances | Adjusted volume |
|---|---|---|---|---|
| Garden path base | 12 ft × 4 ft | 4 in | 10% compaction, 5% waste | ~0.66 yd³ |
| Patio sub-base | 16 ft × 12 ft | 3 in | 12% compaction, 7% waste | ~1.04 yd³ |
| Tree ring | Circle, 6 ft diameter | 2 in | 8% compaction, 5% waste | ~0.13 yd³ |
Examples are illustrative; site conditions and material type can change density and compaction.
Formula used
The calculator finds footprint area, multiplies by depth, then applies allowances:
Adjusted Volume = Raw Volume × (1 + Waste%) × (1 + Compaction%).
- Rectangle:
A = L × W - Circle:
A = π × (D/2)² - Triangle:
A = (B × H) / 2 - Custom:
A = given area
- Raw volume:
V = A × Depth - Unit conversions: ft³↔yd³ and m³↔L.
- Weight:
Weight = Adjusted m³ × Density (kg/m³)
Tip: If you know supplier yards, focus on the adjusted yd³ result.
How to use this calculator
- Select a shape that matches your footprint.
- Enter dimensions using the chosen length unit.
- Set depth for your gravel base thickness.
- Add compaction and waste allowances as needed.
- Press Submit to see results above the form.
- Use higher compaction for crusher run or heavy tamping.
- Increase waste for uneven grades or tight edges.
- Confirm delivery minimums before ordering.
- CSV is great for bids and spreadsheets.
- PDF is handy for printing and sharing.
- Run a calculation first, then download.
Note: This tool provides estimates; consult local guidance for critical builds.
Why gravel base depth matters
A gravel base spreads loads, improves drainage, and helps keep garden surfaces level. Depth drives the final volume more than any other input, so measure several points and use an average. For paths and patios, a consistent base reduces settling and makes the top layer easier to compact. Add a 1–2% slope to move water away and reduce long-term maintenance costs.
Typical base thickness ranges
Light foot-traffic paths often use 2–3 inches of compacted base. Patios, sheds, and cart paths commonly need 4–6 inches, especially on softer soils. If your site holds water or has organic topsoil, excavate to firm subgrade, then rebuild with a thicker base and proper edging. Many projects place the base in 2–3 inch lifts, compacting each layer.
Allowances for compaction and waste
Compaction reduces loose gravel height, so planning only the finished thickness can leave you short. Many installers add 8–15% for compaction, depending on material and tamping method. Waste allowance (often 3–7%) covers raking, trimming edges, and minor over-excavation. This calculator applies both as multipliers to the raw volume. If you use a plate compactor, moisten the gravel; damp material packs more uniformly.
Density, weight, and delivery planning
Suppliers sell by volume, but transport and handling depend on weight. Typical gravel density ranges from 95–110 lb/ft³ (about 1,520–1,760 kg/m³), while crushed stone fines can run higher. The tool converts your adjusted volume into estimated kilograms, pounds, and tons, plus bag counts and rough truck-load equivalents. Use the yard result for ordering, and the weight result to confirm vehicle limits.
Quality checks before ordering
Confirm whether your supplier quotes “loose” or “compacted” yards, then match the allowance settings accordingly. Recheck units, especially inches versus feet on depth. For irregular areas, split the footprint into simple shapes and add results. Consider a geotextile separator on clay or silty soils to reduce mixing. Keep a small buffer for touch-ups, but avoid over-ordering in tight spaces where excess material is hard to store.
FAQs
What depth is typical for a garden path base?
For pedestrian garden paths, 2–3 inches compacted base is common. For carts, patios, or soft soils, plan 4–6 inches. If drainage is poor, excavate deeper, improve subgrade, and compact in lifts to reach the finished thickness.
Which density should I enter for gravel?
If you are unsure, start around 100 lb/ft³ (about 1,600 kg/m³). Crushed stone with fines may be heavier, while rounded gravel can be lighter. Use your supplier’s material ticket when available for the best weight estimate.
Why does the calculator add compaction and waste?
Compaction shrinks loose material after tamping, and waste covers trimming and minor losses. Together they reduce shortages on site. The tool multiplies raw volume by (1 + waste%) and (1 + compaction%) to produce an adjusted order quantity.
How do I handle irregular shapes?
Break the area into rectangles, triangles, and circles that approximate the footprint. Run each shape separately, then add the adjusted yard totals. This method is usually more accurate than guessing one large rectangle for curved garden beds.
What is the difference between raw and adjusted volume?
Raw volume is area × depth, before allowances. Adjusted volume includes your waste and compaction settings, so it better matches what you need to purchase. Use raw for theoretical volume checks, and adjusted for ordering.
How accurate are the bag and truck load estimates?
They are planning aids based on your density value and common load sizes. Bag counts assume full bags and round up. Truck loads use typical capacities, which vary by vehicle and regulations. Always confirm payload limits and delivery sizes locally.