Gravel Calculator
Estimate Gravel Volume, Weight & Cost
Planning a new gravel driveway, a drainage trench, or laying down a base for a concrete or paver patio? Getting the right amount of gravel is crucial. Buying too little leads to multiple delivery fees, while buying too much leaves you with a heavy pile of unused stone. Use our gravel calculator to calculate the exact volume in cubic yards, weight in tons, and estimate your total purchase cost.
How to Calculate Gravel
Gravel calculations depend on geometric volume. Whether your project is a rectangle, circle, or triangle, the fundamental math remains the same: you must find the area in square feet, multiply by the depth in feet, and convert the resulting cubic feet into cubic yards or tons.
Most bulk gravel suppliers sell materials by the cubic yard or by the ton. In the landscaping industry, a 10% waste and compaction buffer is standard practice. Compaction occurs when heavy rollers or plate tampers press down on loose gravel, decreasing its height. A 3-inch layer of loose stone may compress to 2.5 inches after compaction, meaning you must order slightly more loose material to hit your target depth.
Gravel Volume Calculations Step-by-Step
To calculate the gravel requirements manually for a rectangular driveway measuring 30 feet long, 12 feet wide, and 4 inches deep:
- Find the Area: Length × Width = 30 ft × 12 ft = 360 square feet.
- Convert Depth to Feet: 4 inches ÷ 12 inches/foot = 0.333 feet.
- Calculate Cubic Feet: Area × Depth = 360 sq ft × 0.333 ft = 120 cubic feet.
- Convert to Cubic Yards: 120 cubic feet ÷ 27 (since 1 cu yd = 27 cu ft) = 4.44 cubic yards.
- Add 10% Waste Buffer: 4.44 × 1.10 = 4.89 cubic yards.
Converting Cubic Yards to Tons
Why do gravel suppliers quote in tons instead of cubic yards? Many commercial quarries weigh delivery trucks on drive-on scales, which measures weight rather than physical volume. Converting volume (cubic yards) to weight (tons) requires knowing the density of the stone.
While the weight varies depending on moisture content and the exact rock type (limestone, granite, slate), most landscaping gravel weighs roughly 2,700 to 2,800 pounds per cubic yard. Since one US short ton equals 2,000 pounds, a cubic yard of gravel is approximately 1.35 to 1.4 tons. Our calculator uses a multiplier of 1.4 to ensure you have adequate material coverage.
Gravel Depth Requirements by Project Type
| Project Type | Recommended Depth | Stone Type | Compaction Required? |
|---|---|---|---|
| Patio Base (under pavers) | 4 – 6 inches | Crushed run / Crusher run | Yes (Heavy compaction) |
| Walkway / Footpath | 2 – 3 inches | Pea gravel / Decomposed granite | Light tamping |
| Driveway (Base layer) | 6 – 8 inches | 3/4-inch crushed limestone | Yes (Heavy compaction) |
| Driveway (Surface layer) | 2 – 3 inches | #57 Crushed stone | Yes |
| Drainage Trench / French Drain | 12 – 24 inches | 1-inch to 2-inch washed river rock | No |
Types of Landscaping Gravel Explained
- Pea Gravel: Small, round, smooth pebbles about the size of a pea. Pea gravel is comfortable to walk on, making it excellent for garden paths, play areas, and patio accents. However, because the stones are round, they shift easily underfoot and do not compact into a solid surface.
- Crushed Run (Crusher Run / Quarry Process): A mix of crushed stone and fine stone dust. This product is designed to compact extremely well. When water is added and it is packed down, it forms a nearly solid, concrete-like base. It is the gold standard base material under paver patios and concrete slabs.
- River Rock: Larger, smooth stones washed by rivers. Typically used for decorative dry creek beds, around water features, or in garden borders. It is excellent for erosion control but impractical to walk on.
- Decomposed Granite (DG): Fine granite particles that pack down tightly. DG is ideal for natural-looking rustic paths and patio areas. It drains well and can be mixed with stabilizers to prevent washing away in heavy rains.
Pro Tips for Lying Gravel
- Lawn Edging is Essential: Always install a sturdy border or edging (metal, plastic, or concrete pavers) around pea gravel paths. Without edging, gravel will migrate into adjacent grass, creating hazards for lawnmowers.
- Lay Geotextile Fabric: Place a high-quality non-woven landscaping fabric on the subgrade before pouring gravel. This prevents the stones from sinking into the mud and helps suppress weed growth.
- Spread in Layers: If you are pouring a thick 6-inch base, do not dump and spread all 6 inches at once. Spread it in 2-inch increments, compacting each layer before adding the next. This ensures structural stability.
- Check for Base prep: Prior to tamping, check your slope. Patios and walkways must slope away from building foundations at a minimum rate of 1/8 inch per foot (1 inch per 8 feet).
- Laying turf next door? If your gravel borders a fresh lawn, check our Sod Calculator to estimate your turf requirements.
Gravel Sizes & Construction Uses
| Gravel Size / Spec | Common Name | Typical Application | Compacting properties |
|---|---|---|---|
| #3 Gravel (1.5" to 2.5") | Clean Stone | Driveway sub-base, heavy drainage systems | Excellent permeability, low compaction |
| #57 Gravel (0.5" to 1") | Crushed Stone | Retaining wall drainage, concrete aggregate | Good drainage, settles naturally |
| #411 Gravel (Up to 0.75") | Crusher Run / Quarry Process | Patio and driveway surface base | High compaction, binds into solid base |
Frequently Asked Questions
How many tons of gravel are in a dump truck?
A standard single-axle dump truck can carry about 5 to 7 tons of gravel. Larger tri-axle dump trucks can hold 15 to 20 tons. Always confirm truck capacity and driveway clearance restrictions when ordering bulk deliveries.
Can I put gravel directly over grass?
No, pouring gravel directly over grass is not recommended. The grass will die and decay, creating organic soil that permits weed seeds to grow. Furthermore, the weight of vehicles or foot traffic will push the gravel down into the mud. You must scrape off the sod, excavate to the required depth, compact the soil, and lay down weed barrier fabric first.
How much does a yard of gravel cost?
Bulk gravel prices run between $30 and $75 per cubic yard at local quarries, depending on stone quality. When delivered, expect to pay $50 to $120 per yard including shipping, depending on distance. Pre-packaged 50-lb bags at retail stores cost $4 to $8, which translates to a much more expensive rate of $200+ per cubic yard.
- AASHTO Standards - Aggregate sizing specs (#57, #411) for base preparation.
- Federal Highway Administration - Material specifications for gravel base layers.