Gravel Base Calculator
A gravel base calculator finds cubic yards (L × W × depth ÷ 27) × 1.5 t/yd³. A 20 × 10 ft base 4 in thick needs 3.70 tons, or 4.07 with 10%.
What your order looks like
One bulk delivery is usually easier than hauling it yourself.
2.47 yd³ · 3.7 tons
34 wheelbarrow trips (2 cu ft each)
5 pickup loads (0.75 ton each)
1 small dump truck load (6 tons each)
Rules of thumb: A wheelbarrow trip is 2 cubic feet of heavy material, about 200 lb, a load most people can push. A pickup load is 0.75 ton, the payload of a full-size half-ton pickup (1,500 lb). A small single-axle dump truck carries about 6 tons.
How much gravel base you need
A gravel base calculator works out how many tons of compactable stone go under a slab, shed, patio, or walkway. Multiply length × width × base thickness in feet, divide by 27 for cubic yards, then multiply by 1.5 tons per cubic yard. Tons = (L × W × depth in ÷ 12) ÷ 27 × 1.5. A 20 × 10 ft base 4 inches thick needs 3.70 tons, or 4.07 tons with the 10% allowance ticked.
The cost line multiplies tons by your price per ton. Quarries and landscape yards usually price base material by the ton.
What a base layer does
The base sits between the native soil and whatever you build on top. It has three jobs:
- Spread the load. A shed’s corner or a car tire presses on a small spot. A compacted base spreads that over a wider area of soil.
- Drain water. Water runs through and away instead of softening the ground under the surface.
- Stay flat. A well-compacted base keeps pavers level and slabs from cracking at low spots.
Clean stone drains but rolls underfoot. Stone with fines compacts hard. That is why the calculator uses road base at 1.5 tons per cubic yard.
Worked examples
Example 1: Patio base, 20 × 10 ft, 4 in, $40 per ton
- Volume: 20 × 10 × 0.333 = 66.7 ft³ ÷ 27 = 2.47 yd³
- Tons: 2.469 × 1.5 = 3.70 tons
- With 10% extra: 4.07 tons, costing $162.96
Example 2: Shed base, 12 × 16 ft shed, base 1 ft wider all round, 6 in deep, $40 per ton
- Base footprint: (12 + 2) × (16 + 2) = 14 × 18 ft
- Volume: 14 × 18 × 0.5 = 126 ft³ ÷ 27 = 4.67 yd³
- Tons: 4.667 × 1.5 = 7.00 tons
- With 10% extra: 7.70 tons, costing $308.00
Base depth by project and soil
| Project | Firm, well-drained soil | Soft clay or wet ground |
|---|---|---|
| Garden path, walkway | 3–4 in | 6 in |
| Shed or outbuilding | 4 in | 6–8 in |
| Concrete patio or slab | 4 in | 6 in |
| Paver patio (foot traffic) | 4–6 in | 6–8 in |
| Paver driveway | 8 in | 10–12 in |
| Gravel or concrete driveway | 6–8 in | 8–12 in |
These are common practice figures. Local code, a slab design, or a manufacturer’s paver guide may require more.
Tons of base per 100 sq ft
| Depth | Tons per 100 sq ft | Lifts to compact |
|---|---|---|
| 4 in | 1.85 | 1 |
| 6 in | 2.78 | 2 |
| 8 in | 3.70 | 2 |
| 12 in | 5.56 | 3–4 |
Net figures at 1.5 tons per cubic yard.
How to measure and prepare
- Mark the finished outline, then add 6 to 12 inches on each side for the base.
- Dig out sod and topsoil to firm subsoil. The excavation depth is the base plus anything on top, such as 1 inch of sand and the paver thickness.
- Compact the subgrade before any stone goes in.
- Lay fabric on soft soil. Size it with the landscape fabric calculator.
- Measure the base depth you will place after compaction and enter it.
Common mistakes
- Using clean #57 stone as a compacted base. It drains, but it never locks tight. It suits drainage layers, not paver bases.
- One thick lift. A plate compactor cannot pack 8 inches at once. The bottom stays loose and settles later.
- Base the same size as the patio. Edge pavers then sit half on soil and tip over time.
- Skipping slope. Grade the base the same way the finished surface will drain, usually away from buildings.
Related calculators
Building pavers? The paver base calculator includes the sand layer. For a shed, use the gravel shed base calculator. Pouring concrete on top? Size the slab with the concrete slab calculator.
Frequently asked questions
How much gravel do I need for a base?
Multiply length × width × base depth in feet, divide by 27 to get cubic yards, then multiply by 1.5 tons per cubic yard for compactable road base. A 20 × 10 ft base at 4 inches is 2.47 yd³, or 3.70 tons, and 4.07 tons with 10% extra.
How deep should a gravel base be?
Common figures are 4 inches under walkways, sheds, and slabs on firm soil, 4 to 6 inches under paver patios, and 6 to 8 inches or more under driveways or anywhere vehicles drive. Soft clay, poor drainage, and frost-prone ground push every figure deeper.
Why does this calculator use road base at 1.5 tons per cubic yard?
A base layer needs stone with fines, such as road base, crusher run, or Class 5, because the fines pack into the gaps and lock the layer solid. That mix weighs about 1.5 tons per cubic yard, heavier than clean stone at about 1.35.
How far should the base extend past the slab or patio?
A common practice is to run the base about 6 to 12 inches past the edges of the finished surface, so edge pavers and slab corners sit on solid support. For a 12 × 16 ft shed with 1 ft extra each side, measure 14 × 18 ft.
How many lifts should I compact a gravel base in?
Spread and compact in layers of about 3 to 4 inches. A 6-inch base is two lifts and an 8-inch base is two or three. Dampen the material lightly so the fines bind, and run the plate compactor over each lift several times.
Do I need fabric under a gravel base?
On soft, wet, or clay soil, a woven geotextile helps keep the base from sinking into the subgrade and stops mud pumping up into it. On firm, well-drained ground it is often optional.
Estimates only. Verify quantities with your supplier before purchasing.