Paths, drives & bases
Gravel & stone calculator
Measure the area, build it up in layers from the base, and get the volume, the weight in tons or tonnes, the bags and a bulk order.
Gravel and stone for 90 sq ft in 2 layers: 4 in of compacted stone base under 2 in of gravel.
Stone to orderSchedule
- All layers1.89cu yd51 cu ft · 1.44 m³
- Weight2.55US tons2.31 tonnes · 5,100 lb
- 50 lb bags102bagsall layers together
90 sq ft in 2 layers: 4 in of compacted stone base under 2 in of gravel.
| Material | Volume | Weight | Bags |
|---|---|---|---|
| 1. Stone base, compacted4 in finished, +20% | 1.33 cu yd | 1.8 tons | 72 |
| 2. Gravel or pea gravel2 in finished | 0.56 cu yd | 0.75 tons | 30 |
| Layer | By volume | By weight |
|---|---|---|
| 1. Compacted stone base | 1.5 cu yd | 2 tons |
| 2. Gravel | 1 cu yd | 1 ton |
| # | Shape | Size | Area |
|---|---|---|---|
| 1 | Rectangle | 30 ft × 3 ft | 90 sq ft |
| Net area | 90 sq ft | ||
- Weights use the density in each layer. Published figures for these materials range from 2.09 tons to 2.68 tons for this volume, so ask your supplier what they sell by.
- Volumes include the compaction allowance: loose stone settles as it is rolled or driven on, so you order more than the finished depth.
How to use the gravel calculator
- Measure the area as one or more shapes. Paths are long rectangles; Subtract cuts out a bed or a tree ring.
- Build it in layers from the bottom. A path or drive usually has a crushed-stone base under the surface stone; a gravel mulch on a bed is a single layer. Enter the finished depth of each.
- Check the compaction allowance. A base layer starts at 20%: the Gravel Roads manual notes that ordinary compaction from traffic and rain shrinks most gravels by at least 20%. Aggregate Markets suggests about 10% for compaction and settling in general. Loose decorative gravel starts at 0%; add some if you will roll it.
- Density turns volume into weight. The figures that fill in are typical published values, not your quarry's. If your supplier sells by the ton or tonne, ask for their density and type it in.
How deep should gravel be?
The RHS suggests 5–7.5 cm (2–3 in) of gravel as a mulch in planted gravel gardens. UC Master Gardeners treat 2 inches as the practical minimum for a gravel path and allow 4 inches where stepping stones or pavers are set into it. Scotland's specification for rural paths puts at least 100 mm (4 in) of Type 1 sub-base under 25 mm (1 in) of surfacing.
Worked example
A 30 × 3 ft path is 90 sq ft. A 4 in base with 20% for compaction is 36 cu ft (1.33 cu yd); at 1.35 tons per cubic yard that weighs 1.8 tons. Two inches of pea gravel on top is 15 cu ft (0.56 cu yd), about 0.75 tons. As a check, UC Master Gardeners reckon one ton of gravel covers 80 to 120 sq ft at 2 inches.
Sources
- The Engineering ToolBox, Densities of common products: gravel 75–85, crushed limestone 85–95 and dry sand 80–100 lb/ft³.
- The Engineering ToolBox, Dirt and mud densities: dry gravel 105 lb/ft³ (1,680 kg/m³), dry sand 97 lb/ft³ (1,555 kg/m³).
- Aggregate Markets, Crushed stone calculator: crushed stone, gravel and sand at 100 lb/ft³ (1.35 tons per cubic yard); add about 10% for compaction and settling.
- Gravel Roads: Maintenance and Design Manual, Appendix C (archived by the US EPA): ordinary compaction from traffic and rainfall shrinks most gravels by at least 20%.
- Royal Horticultural Society, Drought-resistant gardening (5–7.5 cm of gravel as a mulch) and Gravel gardens (a 1 m³ bulk bag covers around 20 m²).
- UC Master Gardener Program, Gravel pathways in the garden (PDF): 2 in practical minimum, 4 in with stones or pavers, one ton covers 80–120 sq ft at 2 in.
- Scottish Government Rural Payments, New path – unbound surface: at least 100 mm Type 1 sub-base and 25 mm surfacing.
Gravel questions
How much does a cubic yard of gravel weigh?
Published bulk densities for loose gravel run from about 75 to 105 lb per cubic foot, so a cubic yard weighs roughly 2,000 to 2,800 lb: 1 to 1.4 US tons, or 0.9 to 1.3 tonnes. Aggregate Markets uses 100 lb per cubic foot, which is 1.35 tons a yard. Ask your supplier for the figure they sell by.
How much area does a ton of gravel cover?
UC Master Gardeners put it at 80 to 120 sq ft at 2 inches deep. At 1.35 tons per cubic yard, one ton is 20 cu ft, enough for 120 sq ft at 2 inches or 80 sq ft at 3 inches.
How deep should a gravel path be?
UC Master Gardeners call 2 inches a practical minimum and suggest 4 inches if stepping stones or pavers will be set into the gravel. For a path that takes regular wear, Scotland's rural path specification puts at least 100 mm (4 in) of Type 1 sub-base under 25 mm (1 in) of surfacing.
Why add extra for compaction?
Loose stone settles as it is rolled, driven on and rained on. The Gravel Roads manual notes that ordinary compaction from traffic and rainfall shrinks most gravels by at least 20%, so a compacted base needs about a fifth more loose stone than its finished depth. Gravel that is only raked needs less; Aggregate Markets suggests about 10% for compaction and settling.
How much does a 1 m³ bulk bag of gravel cover?
Around 20 m² at 5 cm deep, as the RHS notes. In general, divide 1 m³ by the depth in metres: 25 m² at 4 cm, or 13.3 m² at 7.5 cm.