Gravel, Mulch and Soil Calculator
Calculate how much gravel, crushed stone, sand, topsoil or mulch you need in m³ or cubic yards, its weight in tonnes or tons, and the number of bags.
Typical depths: 5–8 cm (2–3 in) of mulch, 5 cm (2 in) of decorative gravel, 10–15 cm (4–6 in) of crushed stone for a path or driveway base, 10–15 cm (4–6 in) of topsoil for a new lawn.
Loose bulk density filled in from the material. Typed values are kept: use the figure on your supplier's quote when you have it.
Loose material settles once spread and raked or compacted: 10% is common, up to 20–25% for crushed stone that is compacted with a plate.
Gravel, stone and sand bags are usually labelled by weight (30 kg, 50 lb); mulch and soil by volume (56.6 L = 2 cu ft).
- Area
- –
- Volume
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- Volume with extra
- –
- Weight (bulk)
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- Bags
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Estimate only. Bulk density changes with moisture, grading and compaction; suppliers sell by the cubic metre, cubic yard or tonne, so confirm with them before ordering.
How to use the gravel, mulch and soil calculator
- Choose Metric (m, cm, m³, t) or Imperial (ft, in, cu yd, tons).
- Pick the Material: Gravel (pea or river gravel), Crushed stone, Sand (dry), Topsoil or garden soil, Mulch (bark or wood chips), or Other material (enter its density). The Bulk density is filled in for you and can be edited.
- Under Shape of the area, choose Rectangle (length and width), Circle (diameter) or I know the area.
- Enter the Depth of the layer and the Extra for settling and compaction (%).
- Under Bags sold by, choose Weight or Volume and enter the size of one bag.
- Read the Volume, the Volume with extra, the Weight (bulk) and the number of Bags. The steps below the results show every multiplication. Reset defaults restores the example.
Everything is calculated in your browser.
The formulas
- Area: rectangle = length × width; circle = π × (diameter ÷ 2)².
- Volume = area × depth.
- Volume with extra = volume × (1 + extra % ÷ 100).
- Weight = volume with extra × bulk density.
- Bags = volume with extra ÷ bag volume, or weight ÷ bag weight, rounded up to a whole bag.
Example in metric: a 4 × 3 m bed covered with 7.5 cm of pea gravel is 12 m² × 0.075 m = 0.9 m³. With 10% extra, 0.99 m³. At 1.5 t/m³ that is about 1.49 tonnes, or 50 bags of 30 kg.
Example in imperial: a 10 × 10 ft bed with 3 in of mulch is 100 sq ft × 0.25 ft = 25 cu ft, about 0.93 cu yd. With 10% extra, 27.5 cu ft, so 14 bags of 2 cu ft.
Bulk densities used by this tool
Bulk density is the weight of a loose pile, air gaps included, so it is much lower than the density of solid rock. The presets are typical loose (stockpile) values:
| Material | t/m³ | US tons per cu yd |
|---|---|---|
| Gravel (pea or river gravel) | 1.50 | 1.26 |
| Crushed stone | 1.60 | 1.35 |
| Sand (dry) | 1.60 | 1.35 |
| Topsoil or garden soil | 1.30 | 1.10 |
| Mulch (bark or wood chips) | 0.40 | 0.34 |
Sources: the bulk density chart of quarry products and landscape materials published by the Landscape Design Institute (Australia, 2022), which lists round river or pea gravel at 1.50 t/m³ loose, fine crushed rock at 1.70, washed sand at 1.50, screened sandy loam at 1.30 and bark mulch at 0.33 (softwood) to 0.45 t/m³ (hardwood); and Engineering ToolBox tables, which give 1,600 kg/m³ for dry sand and 1,680 kg/m³ for dry gravel. Wet sand or soil can weigh 15–20% more. A US “ton” here is the short ton of 2,000 lb (907 kg).
Tips before ordering
- Bulk suppliers sell by the cubic metre, the cubic yard or the tonne. Order the Volume with extra or the Weight (bulk) and ask for their own density figure.
- A dump truck or a bulk bag (about 1 m³) is usually cheaper than more than 25–30 small bags.
- Compacted bases (crushed stone under pavers or a shed) shrink by 20–25%: raise the extra percentage.
- Put a landscape fabric under decorative gravel and mulch to slow weeds.
Frequently asked questions
How much does a cubic yard of gravel weigh?
Usually 1.25 to 1.4 US tons (2,500 to 2,800 lb), depending on the stone size and moisture. A cubic metre weighs about 1.5 to 1.7 tonnes.
How many bags of mulch make a cubic yard?
A cubic yard is 27 cu ft, so it takes 13.5 bags of 2 cu ft, or 14 bags once rounded up. In metric, 1 m³ is about 18 bags of 56.6 L.
How deep should mulch be?
About 5 to 8 cm (2 to 3 in) around shrubs and in flower beds. Thicker layers can keep water and air from the roots; keep mulch away from tree trunks.
How do I convert cubic yards to tons?
Multiply the cubic yards by the density in tons per cubic yard. With 5 cu yd of crushed stone at 1.35 tons per cubic yard, you get about 6.75 tons.
Why add extra material?
Loose material settles once it is raked, walked on or compacted, and the ground is never perfectly flat. 10% covers most gardens; compacted bases need more.
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