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How to Calculate Gravel
Gravel is typically sold by the ton (bulk delivery) or in bags for smaller projects. Accurate measurement prevents over-ordering and saves money.
Basic Formula
Step by Step
- Measure the area: Length × width in feet
- Choose your depth: 2–4 inches is standard
- Calculate cubic yards: (Area × depth in inches) ÷ 324
- Convert to tons: Cubic yards × density (typically 1.35–1.5 tons/cu yd)
Gravel Types Compared
- Pea Gravel: Smooth, rounded stones ¼"–½". Great for patios, pathways, and drainage. ~1.4 tons/cu yd.
- Crushed Stone: Angular edges, packs tightly. Best for driveways and base material. ~1.4 tons/cu yd.
- River Rock: Smooth, 1"–3" stones. Decorative for landscaping and dry creek beds. ~1.35 tons/cu yd.
- Decomposed Granite: Fine, sandy texture. Natural-looking for pathways and xeriscaping. ~1.5 tons/cu yd.
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Recommended Gravel Depth by Project
- Driveways: 4–6 inches (use crushed stone for compaction) — try our Gravel Driveway Calculator
- Walkways: 2–3 inches of pea gravel or decomposed granite
- Landscape beds: 2–3 inches of decorative stone
- Drainage areas: 6–12 inches of washed gravel
- Under pavers: 4 inches of crushed stone base
For driveways, use a compactable base layer (crushed stone) topped with a decorative layer. This creates a stable surface that doesn't shift.
Gravel Coverage by Depth
| Depth | Sq Ft per Cubic Yard | Sq Ft per Ton | Tons per 100 Sq Ft |
|---|---|---|---|
| 1 inch | 324 sq ft | ~231 sq ft | 0.43 |
| 2 inches | 162 sq ft | ~116 sq ft | 0.86 |
| 3 inches | 108 sq ft | ~77 sq ft | 1.30 |
| 4 inches | 81 sq ft | ~58 sq ft | 1.73 |
| 6 inches | 54 sq ft | ~39 sq ft | 2.59 |
Per-ton figures assume 1.4 tons per cubic yard, the average across common gravels. Suppliers usually sell bulk by weight but quote coverage by volume, so it's worth knowing both.
Gravel Sizes and What the Numbers Mean
Quarries label crushed stone by number, and the numbering is not intuitive. Ordering the wrong grade is the most common gravel mistake — a driveway built on the wrong stone will rut within a season.
| Grade | Stone Size | Compacts? | Best For |
|---|---|---|---|
| #57 | 3/4 in, washed | No | Drainage, French drains, base under concrete |
| #411 / Crusher run | 3/4 in down to dust | Yes | Driveway base, paver base, compacted paths |
| #8 | 3/8 in | Slightly | Paver setting bed, top dressing |
| #2 | 2–2.5 in | No | Deep driveway base, heavy erosion control |
| Pea gravel | 1/4–1/2 in, rounded | No | Patios, paths, playgrounds, dog runs |
| Decomposed granite | Fines to 1/4 in | Yes | Natural-look paths, xeriscaping |
The distinction that matters is washed versus crusher run. Washed stone like #57 has the fines screened out, so water drains straight through and the stones never lock together. Crusher run keeps the stone dust, which fills the voids and lets the material compact into a hard, stable surface.
That means: use crusher run wherever something needs to bear weight — driveway base, under pavers, compacted paths. Use washed stone wherever water needs to move — drains, dry wells, and the layer under a concrete slab.
Rounded stone like pea gravel never compacts at all. It's comfortable underfoot and looks good, but it migrates, which is why pea gravel paths need edging and why pea gravel driveways develop ruts.
Building a Gravel Driveway or Path
- Strip the topsoil. Organic soil compresses and holds water. Excavate down to firm subsoil — usually 8–12 inches for a driveway.
- Grade for drainage. Crown the center of a driveway about 1 inch per 4 feet of width so water sheds to the sides instead of pooling in the wheel tracks.
- Lay geotextile fabric. On soft or clay soil this is the difference between a driveway that lasts and one that sinks. It separates stone from soil so the base can't pump down into the mud.
- Place the base course. 4 inches of #2 or crusher run, compacted in 2-inch lifts with a plate compactor.
- Place the surface course. 2 inches of #411 crusher run for a driveway, or your decorative stone for a path.
- Compact each lift separately. Dumping the full depth and compacting once leaves the middle loose regardless of how long you run the compactor.
- Edge it. Timber, steel, or a paver border keeps loose stone from spreading into the lawn — essential for any rounded gravel.
Mistakes to Avoid
- Using washed stone as a driveway surface. #57 never locks together, so it stays loose and rutted forever. It's a drainage stone, not a driving surface.
- Skipping the fabric on clay. Without separation the base migrates into the subgrade and you lose depth every year.
- Compacting in one thick lift. Thin lifts, every time.
- No crown or edge drainage. Standing water is what destroys gravel driveways in freeze-thaw climates.
- Ordering by volume when the supplier sells by weight. Confirm which unit you're being quoted — a cubic yard is not a ton.
Building a full driveway? Our gravel driveway calculator handles base and surface layers separately.
Frequently Asked Questions
How deep should gravel be for a driveway?
A residential driveway needs 4–6 inches of compacted gravel. Use 4 inches of crushed stone base topped with 2 inches of decorative gravel. For heavy vehicles, go up to 8 inches.
How many tons of gravel per cubic yard?
Most gravel types weigh 1.35–1.5 tons per cubic yard. Crushed stone and pea gravel average about 1.4 tons/cu yd. Decomposed granite is slightly heavier at ~1.5 tons/cu yd.
Is bulk gravel cheaper than bagged?
Yes, significantly. Bulk gravel typically costs $20–50 per ton delivered, while bagged gravel costs $3–5 per 0.5 cu ft bag — roughly 3–4× more per cubic yard. For projects over 1 cubic yard, bulk is usually more economical.
Do I need landscape fabric under gravel?
For most landscaping projects, yes. Landscape fabric prevents weeds from growing through the gravel and keeps it from sinking into the soil. Skip it only for drainage applications where you want water to flow freely.
How much area does a ton of gravel cover?
About 116 square feet at 2 inches deep, or roughly 77 sq ft at 3 inches and 58 sq ft at 4 inches. One ton is about 0.71 cubic yards for typical gravel at 1.4 tons per cubic yard.
What is #57 gravel used for?
Drainage. It's washed 3/4 inch stone with the fines screened out, so water passes straight through and the stones never lock together. Use it for French drains, dry wells, and as the layer under a concrete slab — not as a driveway surface, where it stays permanently loose.
What is crusher run gravel?
Crushed stone that still contains its stone dust and fines, sold as #411 or "crush and run". The fines fill the voids between stones so it compacts into a hard, stable surface. This is what you want for driveway bases, paver bases, and any compacted path.
How deep should gravel be for a walkway?
2–3 inches of pea gravel or decomposed granite over a compacted base. Add edging — rounded stone migrates without something to contain it, and you'll be raking it back off the lawn otherwise.
How many bags of gravel are in a cubic yard?
A 0.5 cubic foot bag means 54 bags per cubic yard. At typical bag prices that's 3–4× the cost of bulk delivery, which is why anything over about a cubic yard should be ordered loose.
Does gravel need to be compacted?
Angular crushed stone should be, in 2-inch lifts with a plate compactor — that's what creates a load-bearing surface. Rounded gravel like pea gravel cannot be compacted no matter what you do; the stones just roll past each other.
Why is my gravel driveway rutting?
Usually one of three things: rounded or washed stone used as the surface instead of crusher run, not enough base depth, or poor drainage. Water is the underlying culprit in most cases — a driveway needs a crown so it sheds to the sides rather than holding water in the wheel tracks.
Sources & Standards
- ASTM International — Standard size numbers for base and drainage stone (ASTM D448) — the #57, #8 and similar classes
- AASHTO — Aggregate base and subbase material requirements (AASHTO M147)
Estimates for planning only. Quantities are calculated from standard coverage and yield figures and include a waste allowance. Always confirm against the manufacturer figures on the product you buy, and check local requirements before ordering. See our full method and assumptions.