Gravel Calculator
Use this free gravel calculator to estimate how much gravel you need for a driveway, patio, pathway, garden bed or drainage project. Enter your area and depth to get the volume, weight in tonnes, cubic yards, cubic metres and an optional cost estimate in CAD. Works in both metric and imperial units.
Gravel Calculator Tool
How much gravel do I need?
The amount of gravel for a project depends on the area you want to cover and how deep the gravel layer should be. The method is simple:
- Find the area. For a rectangle, multiply length × width. For a circle, use π × radius². The calculator does this for you when you choose Rectangle or Circle.
- Choose a depth. Convert it to the same units as your area. A 2-inch (5 cm) layer is common for top dressing; driveways need more.
- Multiply area × depth to get the volume.
- Multiply volume × density to convert the volume into weight (tonnes), which is how gravel is usually sold and delivered.
Volume = Area × Depth
Weight (tonnes) = Volume (m³) × Density (t/m³)
Cost = Weight × Price per unit
Worked example
Suppose you want to cover 200 m² with gravel 3 cm deep using typical loose gravel (density ≈ 1.52 t/m³):
- Volume = 200 m² × 0.03 m = 6 m³
- Weight = 6 m³ × 1.52 t/m³ ≈ 9.1 tonnes
- In cubic yards, 6 m³ ≈ 7.8 yd³
Always add about 5–10% extra for compaction and settling, and round up to the nearest load your supplier delivers.
Gravel coverage chart (how far one tonne goes)
Approximate coverage for one tonne of typical gravel (≈1.5 t/m³) at common depths:
| Depth | Coverage (m²) | Coverage (sq ft) |
|---|---|---|
| 2.5 cm (1 in) | ≈ 26 m² | ≈ 280 ft² |
| 5 cm (2 in) | ≈ 13 m² | ≈ 140 ft² |
| 7.5 cm (3 in) | ≈ 8.9 m² | ≈ 96 ft² |
| 10 cm (4 in) | ≈ 6.7 m² | ≈ 72 ft² |
| 15 cm (6 in) | ≈ 4.4 m² | ≈ 48 ft² |
Figures are approximate and vary with gravel type, particle size, moisture and compaction.
Recommended gravel depth by project
| Project | Recommended depth | Notes |
|---|---|---|
| Decorative gravel / mulch | 5 cm (2 in) | Over landscape fabric to suppress weeds. |
| Garden path / walkway | 5–7.5 cm (2–3 in) | Pea gravel or crushed stone over a compacted base. |
| Patio base | 10 cm (4 in) | Compacted crushed stone under pavers or slabs. |
| Residential driveway | 10–15 cm (4–6 in) | Often built in layers: coarse base + finer top. |
| Drainage / French drain | 10–20 cm (4–8 in) | Clean, angular stone around perforated pipe. |
Types of gravel
Gravel is a loose mixture of rock fragments formed by erosion. It is classified by particle size and how it is produced. Choosing the right type — and entering its density in the calculator — gives a more accurate tonnage estimate.
Pea gravel
Small, rounded stones about the size of a pea (≈ 6–10 mm). Inexpensive and popular for pathways, patios, drainage and around plants thanks to its smooth feel and good drainage. Density ≈ 1.79 t/m³.
Crushed stone & crusher run
Mechanically crushed limestone, dolomite or granite with sharp, angular edges that lock together when compacted. Ideal for driveways, road bases and patio sub-bases. "Crusher run" (a mix of stone and stone dust, e.g. ¾" minus) compacts into a very firm surface. Density ≈ 1.60 t/m³.
River rock
Larger, naturally smoothed stones used decoratively around water features, garden beds and dry creek beds. High drainage capacity. Density ≈ 1.44 t/m³.
Bank gravel (bank run / river run)
A natural mix of large and small fragments, sand and clay found near rivers. Used as fill and as a foundation material with good drainage.
Limestone
Crushed limestone is widely used as a base material and for driveways. It packs well and is often the most economical crushed product. Density ≈ 1.68 t/m³.
What is gravel used for?
Gravel is one of the most widely used construction and landscaping materials. Common uses include:
- Construction: aggregate for concrete and asphalt, road bases and construction fill.
- Driveways & walkways: a durable, permeable surface that is cheaper than paving.
- Drainage: French drains, dry wells and foundation drainage where water must pass through.
- Landscaping: decorative ground cover, garden borders, patio bases and a low-maintenance mulch substitute.
- Water & agriculture: filtration media and ground mineral feed/soil amendments.
Frequently asked questions
How much gravel do I need?
Multiply the area to cover by the depth to get the volume, then multiply by the gravel density to get the weight. For example, 200 m² at 3 cm deep is 6 m³, which is roughly 9 tonnes of typical gravel. The calculator above does this automatically.
How much area does a tonne of gravel cover?
One tonne of typical gravel (≈1.5 t/m³) is about 0.67 m³. At a 5 cm (2 inch) depth that covers roughly 13 m² (about 140 sq ft). See the coverage chart above for other depths.
How many cubic yards are in a tonne of gravel?
For gravel weighing about 1.5 tonnes per cubic metre, one tonne is roughly 0.87 cubic yards. Wetter or denser stone weighs more per cubic yard.
How deep should the gravel layer be?
A workable minimum is 5–10 cm (2��4 inches). Driveways typically use 10–15 cm (4–6 inches), often in layers, while decorative gravel and pathways can use about 5 cm (2 inches).
How much does gravel cost in Canada?
Bulk gravel in Canada generally runs about CAD $15–$60 per tonne depending on type and region, plus delivery. Decorative stone such as river rock costs more. Enter your local price in the calculator for an exact total.
Should I order extra gravel?
Yes. Add about 5–10% for compaction, settling and uneven ground, and round up to the nearest delivery load your supplier offers.
Specialized gravel calculators
Use a dedicated calculator with the right defaults for your project:
Disclaimer: This calculator provides estimates based on the values you enter and typical material densities. Actual quantities vary with gravel type, particle size, moisture and compaction. The cost estimate covers material only and excludes labour, delivery and taxes. Always confirm quantities with your supplier.