Gravel Calculator
By Concrete Knowhow Editorial Team · Updated July 2026 · 7 min read
Quick Answer
Material
Length
Width
Depth
Overage
Extra for compaction and uneven ground. Add 10% for driveways, since gravel settles.
Common Coverage Areas: Quick Reference
Tons calculated using crushed stone (1.5 t/yd³). No waste buffer included.
| Area | Depth | Cubic Yards | Tons (Crushed Stone) |
|---|---|---|---|
| 10×10 ft | 2" | 0.62 | 0.93 |
| 10×10 ft | 4" | 1.23 | 1.85 |
| 10×20 ft | 3" | 1.85 | 2.78 |
| 10×20 ft | 4" | 2.47 | 3.70 |
| 12×40 ft | 4" | 5.93 | 8.89 |
| 20×40 ft | 4" | 9.88 | 14.81 |
| 20×40 ft | 6" | 14.81 | 22.22 |
Gravel Types and When to Use Each One
Gravel is not one product. The right choice depends on whether the material needs to compact into a firm surface (angular crushed stone locks together) or stay loose and decorative (rounded stone does not lock). Densities below are typical bulk values; your supplier can give exact numbers for their stock.
| Type | Size | Typical Density | Best For |
|---|---|---|---|
| Crushed stone #57 | 0.75 to 1 in | 1.4 to 1.5 t/yd³ | Driveway top layer, drainage, concrete base |
| Crushed stone #3 / #4 | 1 to 2.5 in | 1.4 to 1.6 t/yd³ | Driveway base layer, heavy drainage |
| Pea gravel | 0.25 to 0.5 in | 1.3 to 1.4 t/yd³ | Paths, playgrounds, between pavers |
| Crusher run / road base | Fines to 1 in | 1.5 to 1.7 t/yd³ | Compacted bases under pavers and sheds |
| Decomposed granite | Fines to 0.25 in | 1.4 to 1.6 t/yd³ | Natural-look paths and patios |
| River rock | 1 to 3 in | 1.3 to 1.4 t/yd³ | Decorative beds, dry creek beds |
How the Gravel Math Works
Volume first: length in feet times width in feet times depth in feet gives cubic feet, and dividing by 27 gives cubic yards. Depth is normally in inches, so divide it by 12 before multiplying. To convert cubic yards to tons, multiply by the bulk density of your material, typically 1.4 tons per cubic yard for pea gravel and 1.5 for crushed stone.
Worked example. A 12 ft by 40 ft driveway topped with 3 inches of #57 crushed stone: 3 divided by 12 is 0.25 ft. Multiply 12 by 40 by 0.25 to get 120 cubic feet, then divide by 27 to get 4.44 cubic yards. At 1.5 tons per yard that is about 6.7 tons. Add 10 percent for compaction and order roughly 7.3 tons. Most suppliers deliver by the ton, and a typical single-axle dump truck carries about 10 tons, so this fits in one delivery.
Why the buffer matters for gravel specifically: angular stone compacts 10 to 15 percent when driven on or plate-compacted. A driveway that measures perfect on day one will look thin after the first month of traffic if you ordered the bare calculated volume.
How to Lay a Gravel Driveway or Path, Step by Step
- Mark the area. Use stakes and string or marking paint to outline the driveway or path. Call 811 to have underground utilities located before digging.
- Excavate. Dig down 6–8 inches for a driveway, or 3–4 inches for a decorative path. Remove all grass and organic material, which will decompose and cause settling.
- Grade and compact the sub-base. Slope the surface slightly (1–2%) away from structures for drainage. Compact the soil with a plate compactor.
- Install edging. Plastic, steel, or timber edging keeps gravel contained and reduces spreading onto lawns. Set it flush with your desired finished grade.
- Lay landscape fabric (optional). For driveways, skip fabric, because it tears under vehicle weight. For paths and decorative beds, fabric under the gravel helps suppress weeds.
- Add your base layer. For driveways, spread 4 inches of larger crushed stone (#3 or #4 aggregate). Rake level and compact thoroughly.
- Add the top layer. Spread 2–3 inches of your finish gravel (pea gravel, #57 stone, or decomposed granite). Rake level.
- Compact and top up. Compact the surface. Gravel will settle 10–15%. Top up as needed, especially after the first few rains.
Frequently Asked Questions
- How many cubic yards of gravel do I need for a 10×20 ft driveway at 4 inches deep?
- A 10×20 ft area at 4 inches deep is 66.7 cubic feet, or about 2.47 cubic yards. For crushed stone at 1.5 t/yd³ that works out to roughly 3.7 tons. Always add 10% for a driveway to account for compaction.
- How deep should gravel be for a driveway?
- A gravel driveway should have a base layer of 4–6 inches of larger crushed stone (#3 or #4), topped with 2–3 inches of smaller gravel (#57 or pea gravel). Total depth is typically 6–8 inches for light vehicles.
- How much does a ton of gravel cover?
- One ton of pea gravel covers roughly 54 sq ft at 3 inches deep, or about 100 sq ft at 2 inches deep. Crushed stone is slightly denser so covers a little less area per ton.
- What is the difference between cubic yards and tons for gravel?
- Cubic yards measure volume; tons measure weight. Gravel is sold by both, depending on the supplier. To convert, multiply cubic yards by the bulk density of your material, typically 1.4 t/yd³ for pea gravel and 1.5 t/yd³ for crushed stone.
- How much gravel do I need for a French drain?
- A typical French drain trench is 12 inches wide and 18–24 inches deep. For every 10 linear feet, that is roughly 15–20 cubic feet (0.55–0.74 yd³) of gravel. Use clean #57 crushed stone or pea gravel, not pea-sized or fines.
- Should I add a waste buffer for gravel?
- Yes. Add 10% for driveways and paths to account for compaction and settling. For decorative beds you can get away with 5%. It is almost always cheaper to have a little left over than to order a second delivery.