🪨Gravel Calculator
Calculate how much gravel, crushed stone, or sand you need for any area and depth. Get instant volume, weight, and optional cost estimates.
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Volume (m³)
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Gravel Calculator
Knowing how much gravel to order before a landscaping or construction project saves time, money, and wasted delivery trips. This calculator converts your area and depth into volume and weight, then optionally estimates the material cost based on your supplier's pricing per tonne or per cubic metre.
Standard gravel density: approximately 1,520–1,680 kg/m³ (95–105 lb/ft³). Always confirm with your supplier for the specific material.
Gravel calculations come up regularly for driveways, garden paths, drainage systems, landscape edging, and decorative beds. The fundamental calculation is straightforward — volume is area times depth — but most suppliers sell by weight (tonnes), not volume, which requires knowing the density of the specific gravel type. This calculator handles both, plus a waste factor to prevent running short.
How to Measure Your Area
Different area shapes require different approaches:
- Rectangle: Length × Width. A 10 m × 2 m path = 20 m².
- Circle: π × radius². A circular bed 3 m in diameter (radius 1.5 m) = π × 1.5² = 7.07 m².
- Irregular shapes: Divide into rectangles and triangles, calculate each, and add. For a triangle: ½ × base × height.
- Irregular beds: Walk the perimeter with a measuring wheel or use satellite mapping apps to estimate the area, then add 10% for measurement uncertainty.
Recommended Gravel Depths by Application
| Application | Depth (cm) | Depth (in) | Notes |
|---|---|---|---|
| Decorative / garden border | 3–5 | 1–2 | Surface coverage only |
| Garden path (foot traffic) | 5–8 | 2–3 | Weed suppression + walkability |
| Driveway (base layer) | 10–15 | 4–6 | Structural base for vehicle loads |
| Driveway (top dressing) | 5–8 | 2–3 | Surface layer over compacted base |
| French drain / drainage | 15–30 | 6–12 | Drainage aggregate around pipe |
| Weed suppression bed | 5–7 | 2–3 | Over landscape fabric |
Gravel Density Reference
Different gravel types have different bulk densities. Using the correct density ensures your weight and cost estimates are accurate:
- Pea gravel / river gravel: 1,520–1,600 kg/m³
- Crushed stone (3/4" angular): 1,600–1,680 kg/m³
- Limestone screenings: 1,680–1,760 kg/m³
- Crushed concrete (recycled): 1,440–1,520 kg/m³
- Decorative pebbles: 1,400–1,520 kg/m³ (varies significantly)
Converting Volume to Tonnes
Most gravel suppliers sell by the tonne (metric ton = 1,000 kg) or US ton (2,000 lb = 907 kg). To convert: Tonnes = Volume (m³) × Density (kg/m³) ÷ 1,000. For 3 m³ of standard pea gravel at 1,600 kg/m³: 3 × 1,600 ÷ 1,000 = 4.8 tonnes. Always ask your specific supplier for their material's density — prices are quoted per tonne, so density errors directly translate into cost errors.
Waste Factor and Ordering Tips
Adding a 5–10% waste factor accounts for gravel lost around edges, settling, and measurement inaccuracies. For irregular or sloped areas, use 10–15%. It is almost always cheaper to order 10% extra than to pay for a second delivery. If your project is borderline between two round numbers of tonnes, order the larger amount — leftover gravel can be used to top up settling areas in subsequent years.
Frequently Asked Questions
How many tonnes of gravel do I need for a 10 m × 5 m area at 5 cm deep?
Volume = 10 m × 5 m × 0.05 m = 2.5 m³. At a typical pea gravel density of 1,600 kg/m³, weight = 2.5 × 1,600 = 4,000 kg = 4 tonnes. Adding a 10% waste factor brings the order to 4.4 tonnes. Most suppliers sell in 1-tonne increments, so order 5 tonnes to have a small buffer.
What is the difference between pea gravel and crushed stone?
Pea gravel consists of naturally rounded, smooth stones, typically 6–10 mm in diameter. It is comfortable underfoot, drains well, and looks attractive in garden settings. Crushed stone (or crushed limestone) has angular, jagged edges that interlock under load, making it more stable for driveways and structural applications. Pea gravel will shift under vehicle traffic and is better suited to decorative or light foot-traffic applications.
Do I need landscape fabric under gravel?
Landscape fabric prevents weeds from pushing up through gravel in decorative beds and helps prevent gravel from sinking into soil over time. It is recommended for decorative garden applications but not for driveways (where it can trap water and degrade under vehicle loads) or drainage trenches (where it can become clogged with sediment). If you use landscape fabric, pin it down securely at all edges to prevent it from shifting under the gravel.
How deep should a gravel driveway be?
A standard residential gravel driveway should have 10–15 cm (4–6 inches) of base aggregate (typically larger crushed stone, #57 or similar) plus a 5–8 cm (2–3 inch) surface layer of finer gravel. The base layer provides structural support and drainage; the surface layer provides an even, attractive finish. In areas with clay soils or heavy vehicles, increase the base to 20 cm (8 inches) for long-term stability.
How do I stop gravel from spreading off a path or driveway?
Edge restraints are the most effective solution. Concrete, steel, plastic, or timber edging installed along both sides of the path or driveway at gravel surface level keeps the material contained. Deeper compacted edges of the gravel itself also help. For paths, installing the gravel in a slightly depressed channel (even 3–5 cm below surrounding ground level) naturally contains the material with minimal formal edging.
Is recycled concrete a suitable substitute for natural gravel?
Recycled crushed concrete is an economical and environmentally sustainable alternative for many gravel applications. It performs well as a driveway base layer, drainage aggregate, and back-fill material. It is slightly less dense than natural stone (approximately 1,440–1,520 kg/m³) and may have variable particle sizes depending on the source. It can raise soil pH over time if used extensively in garden beds, so it is best reserved for structural applications away from plants.
What does a tonne of gravel look like and how much space does it fill?
One tonne of standard gravel has a bulk volume of approximately 0.6–0.67 m³ (600–670 litres). On a standard flatbed ute or pickup truck, 1–1.5 tonnes is a typical load. To visualize: a 1 m × 1 m square covered 5 cm deep with gravel uses about 0.05 m³ and weighs roughly 80 kg. A typical small car trailer (1.5 m × 2.4 m × 0.4 m high) holds approximately 1.5–1.7 m³ or about 2.5 tonnes of gravel when fully loaded.