Gravel Calculator · https://calcnaut.com/gravel-calculator/
Gravel Calculator
Enter your area and depth to get the gravel you need in tons and cubic yards, plus bags for small jobs. Measure in feet and inches, a waste allowance is built in, and the formula is shown so you can check the math.
This is an estimate, not professional advice. Check your inputs and verify the result against your plans and local building code before you build or order. See terms and disclaimer.
How this calculator works
Volume (ft³) = Length(ft) × Width(ft) × (Depth(in) ÷ 12)With waste = Volume × (1 + Waste% ÷ 100)Cubic yards = Volume(ft³) ÷ 27Weight (lb) = Cubic yards × density (crushed gravel ≈2,800 lb/yd³, pea gravel ≈2,650, crusher run ≈2,500, sand & gravel fill ≈2,900)Tons = Weight(lb) ÷ 2,000Bags (0.5 ft³) = Volume with waste ÷ 0.5Enter your dimensions and the result updates instantly. A waste allowance is included so you order slightly over rather than running short mid-pour, and ready-mix is rounded up to the nearest quarter yard, which is how it is sold.
Worked example
A 20 ft × 10 ft single-car driveway spread 4 inches deep with crushed gravel, and a 10% waste allowance. Inputs: Area length 20 ft, Area width 10 ft, Depth 4 in, Material 1, Waste allowance 10 %. Result: 3.8 tons.
Gravel needed for common projects
Calculated with crushed gravel (2,800 lb/yd³) and a 10% waste allowance. Tap a project to load it in the calculator above.
| Slab size | Gravel needed (tons) | Volume (yd³) | |
|---|---|---|---|
| Walkway, 3 × 50 ft (3 in) | 2.14 | 1.53 | Use → |
| Shed pad, 10 × 10 ft (4 in) | 1.9 | 1.36 | Use → |
| Single driveway, 10 × 40 ft (4 in) | 7.6 | 5.43 | Use → |
| Double driveway, 20 × 40 ft (4 in) | 15.21 | 10.86 | Use → |
| Patio base, 12 × 12 ft (4 in) | 2.74 | 1.96 | Use → |
| Large driveway, 20 × 100 ft (4 in) | 38.02 | 27.16 | Use → |
Method & assumptions
Gravel is sold by weight (the ton) or by volume (the cubic yard), so we first find the volume of the area you are filling, then convert it to weight using the density of the material you picked. Volume in cubic feet is length times width times depth, converted from inches to feet, and cubic yards is that figure divided by 27. Bulk density for natural sand and gravel aggregate typically falls between 95 and 105 lb per cubic foot, or roughly 2,565 to 2,835 lb per cubic yard, under the bulk-density test method in ASTM C29. Crusher run and paver base carry more fines packed between the larger stones, which is why we use a lower per-yard density band for those than for clean, screened gravel.
The waste allowance covers two different things depending on your project. For a loose decorative topping, 10% covers normal spillage and an uneven subgrade. For a compacted base course under a driveway, patio or paver project, plan on 10 to 20% extra loose material, because compaction packs the stone tighter and reduces the loose volume you started with; heavily compacted base courses can lose close to a third of their loose volume. We round the ton and cubic-yard figures for ordering, and round bag counts up to whole bags, since you cannot buy part of one.
Depth depends on the job: about 2 inches is enough for a decorative topping over landscape fabric, 3 to 4 inches suits a walkway or a single-layer driveway surface, and 6 inches or more of compacted base is standard under a driveway that sees regular vehicle traffic, per the guidance in the U.S. DOT/EPA gravel roads design manual for unpaved road sections. Below roughly one cubic yard, bagged gravel at a home center is usually more practical than arranging a bulk delivery, which the result flags automatically.
Pro tips and common mistakes
- Match the material to the layer. Use crusher run or paver base for the compacted structural layer, and save clean crushed gravel or pea gravel for the visible surface course. Mixing the two jobs wastes the more expensive decorative stone underground.
- Compact in layers, not all at once. Spread and compact gravel in lifts of 4 inches or less with a plate compactor. Trying to compact a deep pour in one pass leaves the bottom loose and the finished depth short of your plan.
- Lay geotextile fabric first. A woven fabric barrier under the gravel keeps it from sinking into the subgrade and stops weeds from pushing through. Skipping it means topping up the gravel again within a year or two.
- Order by the ton, check the yard. Most suppliers price and load gravel by the ton, but dump trucks are rated by volume. Know both figures, since a truck that is full by volume may be under its weight limit or vice versa on very dense material.
- Crown or slope the surface. Pitch a gravel driveway or path slightly toward the edges, about 1/4 inch per foot, so water sheds off the surface instead of pooling and washing out the fines between the stones.
Frequently asked questions
How much gravel do I need for a 10x10 area?
How many tons of gravel are in a cubic yard?
How deep should a gravel driveway be?
Do I need extra gravel for compaction?
Is it cheaper to buy gravel by the ton or the yard?
References
- Gravel (Wikipedia)
- U.S. DOT/EPA: Gravel Roads Maintenance and Design Manual
- ASTM C29: Bulk density and voids in aggregate
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