Calculate tons, cubic yards, and project cost for any gravel type — with a live depth preview and multi-zone planner.
Gravel is one of the most commonly under-ordered or over-ordered materials in landscaping and construction. Order too little and you need a second delivery with a second delivery fee. Order too much and you have several tons of stone sitting on your driveway. The math is straightforward once you understand the three conversions that matter: area to volume, volume to cubic yards, and cubic yards to tons — and why the last step depends entirely on which type of rock you are using.
For a rectangular area, multiply length by width in feet to get square feet. For a circular area (a round planting bed or tree ring), use the formula π times radius squared — where radius is half the diameter. A 10-foot diameter circle has a radius of 5 feet: 3.14159 × 5 × 5 = 78.5 square feet. For a long narrow path, length times width gives the correct area just like a rectangle — the path shape is simply a rectangle that happens to be much longer than it is wide. For irregular areas, break them into smaller rectangles and circles, calculate each, and add the results.
Once you have your area in square feet, multiply by the depth in feet (not inches — convert by dividing inches by 12). A 200 square foot area at 4 inches deep is 200 × (4/12) = 66.7 cubic feet. Divide by 27 to convert to cubic yards: 66.7 ÷ 27 = 2.47 cubic yards. Always add a waste factor of 10% for rectangular areas and 15% for irregular shapes. Gravel settles into the sub-base and spreads beyond the intended edges, so the calculated volume is always slightly less than what you will actually need.
This step is where most calculators get it wrong — they use a single universal density figure for all gravel types. In reality, different rock materials have dramatically different bulk densities. Crushed stone (granite, limestone, basalt) runs 2,600–2,800 pounds per cubic yard. Pea gravel is approximately 2,800 pounds per cubic yard. River rock runs slightly lighter at 2,500–2,600 due to its smooth rounded shape leaving more air space. Decomposed granite, when compacted, reaches 2,900 pounds per cubic yard and is one of the heaviest common landscaping gravels. Lava rock is the dramatic outlier — its porous vesicular structure means it weighs only 1,200–1,400 pounds per cubic yard, roughly half the weight of crushed stone for the same volume. This matters enormously: replacing crushed stone with lava rock on a 5-ton driveway order means you actually need about 10 cubic yards instead of 7.
| Rock Type | Density (lb/yd³) | Tons per yd³ | yd³ per Ton | Best Applications |
|---|---|---|---|---|
| Pea Gravel | 2,800 | 1.40 | 0.71 | Pathways, playgrounds, drainage |
| Crushed Stone | 2,700 | 1.35 | 0.74 | Driveways, base layers, drainage |
| River Rock | 2,600 | 1.30 | 0.77 | Decorative, erosion control, dry creek |
| Decomp. Granite | 2,900 | 1.45 | 0.69 | Paths, patios, compacted surface |
| Lava Rock | 1,300 | 0.65 | 1.54 | Mulch replacement, planters, fire pits |
| Limestone Chip | 2,610 | 1.31 | 0.77 | Driveways, paths, drainage |
Depth is the other variable most people get wrong. Too shallow and the gravel shifts, migrates, and does not provide adequate base support. Too deep and the project costs 50% more for marginal additional benefit. The correct depth depends on what the gravel will be used for, how much traffic it will receive, and whether it is decorative or structural.
| Application | Min Depth | Ideal Depth | Notes |
|---|---|---|---|
| Decorative mulch replacement | 2" | 2–3" | Weed barrier recommended underneath |
| Garden path (foot traffic) | 3" | 4" | Edging required to contain stone |
| Patio / seating area | 4" | 4–6" | Compact base layer recommended |
| Residential driveway | 4" | 6" | 3–4" base + 2" top coat ideal |
| Heavy vehicle driveway | 6" | 8–12" | Compacted sub-base required |
| French drain / drainage | 12" | 12–18" | Washed stone #57 preferred |
| Pipe bedding | 4" above pipe | 6" above pipe | Clean washed stone only |
The economics of gravel purchasing change dramatically with project size. For a small garden accent or a single tree ring, bags of gravel from a home improvement store are often the practical choice even if the per-ton cost is higher — because the supplier minimum order for bulk delivery is typically 3–5 tons regardless of what you actually need. But for any project requiring more than 2–3 cubic yards, bulk delivery is almost always significantly cheaper per unit and eliminates dozens of heavy lifting trips.
Bulk gravel is priced per ton, delivered to your site by a dump truck. Prices vary significantly by region, rock type, and distance from the quarry. National averages range from $25–$45 per ton for standard crushed stone and $30–$55 per ton for specialty materials like decomposed granite or river rock. These prices typically include delivery within a set radius — ask your supplier if delivery is included and what the surcharge is beyond their standard delivery zone. Many suppliers apply a minimum order surcharge (often $50–$100) for orders under their truck minimum of 3–5 tons, making small bulk orders expensive per ton despite the lower base price.
Pre-bagged gravel from big-box retailers runs $4–$8 per 50-pound bag. At 2,700 pounds per cubic yard for crushed stone, you need 54 bags per cubic yard — costing $216–$432 per cubic yard in bags versus $35–$65 per cubic yard for the same stone in bulk. The bag premium is 5–8 times higher on a per-cubic-yard basis. However, bags eliminate the need for a vehicle that can accept a dump load, eliminate the risk of excess material you cannot return, and allow precise quantities without minimums. For projects under 0.5 cubic yards (approximately 27 bags), bags are often the right financial and logistical choice.
To convert tons to 50-pound bags: multiply tons by 2,000 to get pounds, then divide by 50. For 1 ton of gravel: 1 × 2,000 ÷ 50 = 40 bags. For 3 tons: 120 bags. A 0.5 cubic yard project using crushed stone at 1.35 tons per cubic yard needs 0.675 tons, or approximately 27 bags of 50-pound gravel. At $6 per bag that is $162 in materials. The same 0.675 tons in bulk at $45/ton is $30 in material — but the supplier's minimum order of 3 tons at $45/ton plus $75 delivery is $210, making bags less expensive for this project size despite the higher per-ton bag cost.