How to use the gravel calculator
Ordering gravel, crushed stone, sand, topsoil or mulch comes down to the same two questions: how much space are you filling, and how does the supplier sell the material? Landscape suppliers sell by the cubic yard or cubic metre, quarries and builders' merchants often sell by the ton or tonne, and garden centres sell bags. This calculator works out the volume from your area and depth, adds an allowance, and converts it into all three.
- Choose units. US mode takes feet and inches and returns cubic yards and US (short) tons. Metric mode takes metres and millimetres and returns cubic metres and tonnes.
- Pick the shape. Use a rectangle for paths, patios and driveways, a circle for tree rings and round beds, or enter a known area if you have measured it from a plan. Split odd shapes into pieces and add them up, or get the total from the square footage calculator.
- Enter the depth of the finished layer.
- Choose the material. Each preset loads a typical density, which you can overwrite with your supplier's figure.
- Set the extra percentage for compaction and waste, and the bag size if you are buying bags.
Gravel volume and weight formulas
Area = length × width (rectangle) or π × (diameter ÷ 2)² (circle)
Volume = area × depth × (1 + extra %)
Cubic yards = cubic feet ÷ 27 · 1 yd³ = 0.7646 m³
Weight (tonnes) = volume (m³) × density (t/m³) · 1 tonne = 1.1023 US tons
Bags = ⌈volume ÷ bag size⌉
Keep the depth and the area in the same unit before multiplying: 3 in is 0.25 ft and 75 mm is 0.075 m. Forgetting that step is the most common reason a gravel order comes out twelve times too large.
| Material | Typical density (estimate) | Per cubic yard (estimate) |
|---|---|---|
| Crushed stone / gravel | 1.5–1.7 t/m³ | 1.3–1.4 US tons |
| Pea gravel | 1.4–1.6 t/m³ | 1.2–1.35 US tons |
| Crushed base (loose) | 1.7–1.9 t/m³ | 1.4–1.6 US tons |
| Dry sand | 1.5–1.7 t/m³ | 1.3–1.4 US tons |
| Topsoil | 1.1–1.4 t/m³ | 0.9–1.2 US tons |
| Mulch / bark | 0.3–0.5 t/m³ | 500–800 lb |
Densities vary with rock type, grading and moisture. They are planning figures, not supplier data.
Worked examples
A gravel garden path
A path 20 ft long and 4 ft wide at 3 in deep holds 80 × 0.25 = 20 ft³, or 0.74 yd³. With 10% extra that is 0.81 yd³ (22 ft³). At 1.6 t/m³ crushed stone weighs about 1.1 US tons, or 44 bags of 0.5 ft³. One ton of the same stone covers about 80 ft² at 3 in.
A metric driveway sub-base
A 6 × 3 m parking pad with a 100 mm crushed base needs 18 × 0.1 = 1.8 m³ of compacted stone. Adding 15% for compaction brings the loose order to 2.07 m³, which at about 1.8 t/m³ is roughly 3.7 tonnes. The surface gravel goes on top as a separate layer, so run the calculator again for it.
Mulch around a tree
A mulch ring 8 ft across at 3 in deep covers π × 4² = 50.3 ft² and holds 12.6 ft³, or 0.47 yd³. In 2 ft³ bags that is 7 bags, or 7 with 10% extra as well, since 13.8 ft³ still fits in 7 bags. At about 0.4 t/m³ the whole ring weighs only around 140 kg (310 lb).
Who this calculator helps
- Landscape architects and garden designers scheduling hard and soft landscape materials for a planting or paving plan.
- Architects putting early quantities on site works, driveways, drainage trenches and sub-bases.
- Contractors and landscapers turning a site measure into a delivery order in yards, tons or bulk bags.
- Homeowners pricing a path, patio base, play area or new beds before ordering.
- Students learning how volume, density and compaction tie together in site work.
Practical tips
- Ask the supplier whether they sell by loose volume or by weight, and use their density if they give one.
- Lay a geotextile under paths and driveways to keep the stone from sinking into the subsoil.
- Compact crushed base in layers of about 75–100 mm (3–4 in); thick single lifts don't compact well.
- Check slopes and falls on paths and drives with the slope calculator, and price concrete edging or footings with the concrete calculator.
- Check the truck or trailer limit before ordering by weight: a small trailer often can't carry a full ton.
Want to see the gravel garden before it goes in? Try the new layout on a photo of the site with Landscape.
