Gravel Calculator
Not sure how much gravel you need? This free gravel calculator takes the guesswork out of figuring gravel for driveways, paths, gardens, and landscaping jobs. Enter the area dimensions and depth, choose your material type, and get instant results in tons, cubic yards, and an optional cost estimate. Works for crushed stone, pea gravel, limestone, decomposed granite, and river rock.
All calculations use standard published formulas. Results are for informational use only.
Material type
Unit system
How to use this gravel calculator
- Choose your material - Crushed stone is the most common choice for driveways and base layers. Pea gravel works well for paths and drainage. Decomposed granite is popular for landscaping and patios.
- Select unit system - Imperial uses feet and inches; metric uses meters and centimeters.
- Enter dimensions - Measure the length and width of the area to be covered. For irregular shapes, break them into rectangles and add the results.
- Enter depth - Use 2-3 inches for decorative coverage, 4-6 inches for driveways, and up to 12 inches for a structural base layer.
- Optional: add price per ton - Enter your supplier's quoted price to get an instant material cost estimate.
Gravel calculation formula
The online gravel calculator works in three steps: volume calculation, unit conversion, and weight conversion.
Volume (yd^3) = ft^3 / 27
Weight (tons) = yd^3 x density (tons/yd^3)
Metric: Volume (m^3) = Length (m) x Width (m) x Depth (cm) / 100
Weight (tonnes) = m^3 x density (t/m^3)
Gravel material density reference
Densities vary by material type. Use these values to convert your volume to weight when ordering from a supplier who quotes by the ton.
| Material | Density (tons/yd^3) | Density (t/m^3) |
|---|---|---|
| Crushed Stone / Gravel | 1.50 | 1.60 |
| Pea Gravel | 1.40 | 1.52 |
| Limestone (57 or 304) | 1.50 | 1.60 |
| Decomposed Granite | 1.35 | 1.45 |
| River Rock / Landscape Rock | 1.30 | 1.40 |
Crushed stone and limestone are the densest common options. River rock is the lightest. Always confirm density with your supplier for the specific product.
Recommended gravel depth by project type
Using the right depth for your project prevents costly over-ordering and under-engineering. These are compacted depths - order 15-20% more loose material to achieve the target compacted depth.
| Project type | Depth (imperial) | Depth (metric) |
|---|---|---|
| Decorative garden / flower bed | 2-3 in | 5-8 cm |
| Walkway / footpath | 3-4 in | 8-10 cm |
| Driveway (residential) | 4-6 in | 10-15 cm |
| Driveway (heavy vehicles) | 6-8 in | 15-20 cm |
| Drainage French drain | 8-12 in | 20-30 cm |
| Structural base under concrete | 4-6 in | 10-15 cm |
| Playground / play area surface | 6-9 in | 15-23 cm |
For driveways, a 4-6 inch compacted base of crushed stone is the minimum. Use 6-8 inches for heavy truck traffic or poor soil drainage.
Figuring gravel for a driveway - what you need to know
Gravel driveways are one of the most common uses for a driveway gravel calculator. A well-built gravel driveway needs at least two layers: a compacted base of large crushed stone (57 limestone or 304 road base, 4-6 inches) topped with a finer surface stone (pea gravel or crusher run, 2-3 inches). Calculate each layer separately and add the totals.
Why suppliers sell by weight, not volume
Gravel and crushed stone are sold by the ton because weight is easy to verify at the truck scale and is consistent regardless of how the material was loaded. Volume varies with particle size, moisture content, and compaction. When the supplier quotes a price "per ton," use this calculator to convert your volume to tons first, then multiply by the price.
Common mistakes when figuring gravel
- Using volume instead of weight - Suppliers quote tons. Always convert volume to weight using the density factor.
- Not accounting for compaction - Gravel compacts 10-15% when tamped or driven over. Order 10-15% more than the loose calculation shows.
- Wrong depth for the application - Two inches works for decoration; it does not work for a driveway. Use the recommended depths above.
- Treating all gravel as the same density - River rock is noticeably lighter than crushed limestone. Choose the correct material type in this calculator.
Worked examples
Example 1 - Driveway (imperial)
A 12 ft x 50 ft driveway at 4 inches of crusher-run gravel: depth = 4/12 = 0.333 ft; volume = 12 x 50 x 0.333 = 200 ft^3 = 7.41 yd^3. At 1.5 tons/yd^3: 11.1 tons. With 12% compaction buffer: order 12.5 tons.
Example 2 - Garden path (metric)
A 15 m x 1.2 m garden path at 8 cm of pea gravel: depth = 0.08 m; volume = 15 x 1.2 x 0.08 = 1.44 m^3. At 1.52 t/m^3 (pea gravel): 2.19 tonnes. Add 10% compaction: order 2.4 tonnes.
Example 3 - Decorative bed (imperial)
A 20 ft x 8 ft flower bed at 3 inches of river rock: volume = 20 x 8 x 0.25 = 40 ft^3 = 1.48 yd^3. At 1.3 tons/yd^3: 1.92 tons. Order 2 tons.
Quick tips for gravel projects
- Always order 10-15% more than calculated. Gravel compacts when tamped or driven over. Without a compaction buffer you will run short before the project is done.
- Calculate multi-layer projects layer by layer. A driveway with a crushed-stone base and a pea-gravel surface uses different material and depth for each layer - run the calculator separately for each and add the totals.
- Convert to tons before calling your supplier. Suppliers quote per ton. Use the density reference table above to convert your cubic yards or cubic meters to tons before placing your order.
- Match material to application. Crushed stone is for structural bases; pea gravel works for drainage and decorative paths; river rock is for ornamental beds. Using the wrong type causes premature failure or wasted spend.
Frequently Asked Questions
How do I figure out how much gravel I need?
Multiply the length by the width to get the surface area, then multiply by the depth to get volume. In imperial: use feet for length and width, and inches for depth (divide depth by 12 to convert to feet first). Divide the cubic footage by 27 to get cubic yards. Then multiply cubic yards by the gravel density - typically 1.5 tons/yd^3 for crushed stone - to get tons. Add 10-15% for compaction and spillage.
How many yards of gravel do I need for a driveway?
A typical residential driveway is 12 ft wide x 40 ft long with a 4-inch thick base. Volume: 12 x 40 x (4/12) = 160 ft^3 = 5.93 yd^3. At 1.5 tons/yd^3, that is about 8.9 tons of crushed stone. Most suppliers recommend a 4-6 inch compacted depth for driveways, so figure 6-10 tons for a standard driveway.
How much does a yard of gravel cover?
One cubic yard of gravel covers approximately 100 sq ft at 3 inches deep, 81 sq ft at 4 inches, or 162 sq ft at 2 inches. Use the formula: Coverage (sq ft) = 27 x 12 / Depth (inches). A ton of average-density gravel covers roughly 67-70 sq ft at 4 inches deep.
What is the difference between crushed stone and pea gravel?
Crushed stone has angular edges that lock together when compacted - ideal for driveways, base layers, and structural fill. Pea gravel has smooth, rounded edges that don't compact as well but are comfortable underfoot - better for pathways, playgrounds, and decorative landscaping. Pea gravel is also slightly lighter per cubic yard (about 1.4 tons vs. 1.5 tons for crushed stone).
How deep should gravel be for a driveway?
For a residential gravel driveway, a minimum of 4 inches of compacted gravel is recommended, though 6 inches is better for areas with heavy vehicles or poor drainage. Use a base layer of compacted crushed stone (57 limestone or 304 road base) topped with a finer gravel or pea gravel layer for appearance. Total depth before compaction should be 5-8 inches to achieve a 4-6 inch compacted base.