This gravel base calculator works out how much crushed stone to order for the base course under an asphalt driveway, parking pad or lot. Most online gravel calculators multiply area by depth and stop there, which quietly assumes the stone in the truck takes up the same space once it is rolled. It does not. Dense-graded base shrinks noticeably when it is compacted, so this tool adds a compaction allowance, then waste, then converts to tons with the weight of your chosen material and splits the order into tandem and tri-axle loads.
Quick answer: for crusher run or road base, tons ≈ square feet × compacted depth (in) ÷ 324 × 1.875. That is 1.5 tons per loose yard plus 25% for compaction.
A 12 × 50 ft driveway (600 sq ft) with a 6-inch compacted base needs about 21 tons, or about 22 tons with 5% waste: two tandem loads or two tri-axle loads.
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How to Calculate Gravel Base for a Driveway
- Find the area in square feet. Length × width. A 12 × 50 ft driveway is 600 sq ft.
- Get the compacted volume. Square feet × depth in inches ÷ 12 ÷ 27. At 6 inches: 600 × 6 ÷ 12 ÷ 27 = 11.11 cubic yards. This is the space the finished base fills.
- Add the compaction allowance. Loose stone must be bought to fill that space after rolling. At 25%: 11.11 × 1.25 = 13.89 loose cubic yards.
- Add waste. Uneven subgrade, edges and spillage. At 5%: 13.89 × 1.05 = 14.58 cubic yards to order.
- Convert to tons. Multiply by the loose weight of the material. At 1.5 tons per yard: 14.58 × 1.5 = 21.9 tons.
- Divide by truck capacity and round up. 21.9 ÷ 14 = 1.6, so two tandem loads. 21.9 ÷ 20 = 1.1, so one full tri-axle plus a small top-up, or two tri-axles.
Why this matters: simply multiplying 11.11 compacted yards by 1.5 gives 16.7 tons, about 5 tons short of what fills the box. As a cross-check, Penn State's Center for Dirt and Gravel Roads tells buyers of its Driving Surface Aggregate (a dense-graded crushed stone placed 8 inches loose and rolled to 6) to order 0.04 tons per square foot. That works out to 2.16 tons per compacted cubic yard for moist, well-graded stone, even more than this calculator's default of 1.875. If your quarry quotes tons per yard for compacted base, set the compaction allowance to 0.
Base Material Weights and Compaction
Quarries convert yards to tons with their own factors, and they vary with rock type, gradation and moisture. One Ohio producer, Kokosing Materials, tells customers to multiply cubic yards by 1.65 for clean stone such as #57 and by 1.75 for base materials such as 304 and screenings. A national delivery marketplace lists road base and crushed concrete at about 2,800 lb per yard and asphalt millings at about 2,500 lb. The defaults below sit inside those ranges. Always use your supplier's number if you have it.
| Material | Loose t/yd³ | Typical range | Compaction allowance | Tons per compacted yd³ |
|---|---|---|---|---|
| Crusher run / road base / DGA | 1.50 | 1.4 to 1.75 | 25% | 1.88 |
| #57 clean crushed stone | 1.40 | 1.35 to 1.65 | 10% | 1.54 |
| Crushed concrete | 1.35 | 1.2 to 1.4 | 20% | 1.62 |
| Asphalt millings (RAP) | 1.25 | 1.15 to 1.4 | 25% | 1.56 |
Weights vary by quarry and moisture; wet stone weighs more per yard. Ranges are rules of thumb from producer and supplier figures, not a specification.
How much does gravel compact? Dense-graded material with fines (crusher run, DGA, 21A, 2A, 304, road base) packs down the most because the fines fill the gaps between larger stones. Penn State's Driving Surface Aggregate goes from 8 inches loose to 6 inches compacted, which is a 25% loss in thickness and needs 33% more loose material than the finished volume. Expect a 15% to 35% allowance for dense-grade, depending on moisture and roller. Clean, single-size stone like #57 has few fines and settles much less, so 5% to 15% is typical. Crushed concrete is lighter than natural stone; the FHWA notes its lower compacted unit weight gives "higher yield" per ton.
Note the difference between shrinkage and allowance. If a layer shrinks by 20% (10 in loose to 8 in compacted), you need 25% more loose material, because 1 ÷ 0.8 = 1.25. The calculator asks for the allowance.
How Thick Should the Base Be?
| Project | Asphalt on top | Compacted base | Notes |
|---|---|---|---|
| Walkway or path | 2 in | 4 in | Firm, well-drained soil |
| Residential driveway, cars | 2 to 3 in | 6 to 8 in | Go deeper on clay or wet ground |
| Driveway with RV, trucks | 3 to 4 in | 8 to 12 in | Two layers of stone is common |
| Parking lot, cars | 3 to 4 in | 8 to 12 in | Engineered design for large lots |
| Gravel driveway (no paving) | None | 8 to 12 in total | Coarse stone below, surface stone on top |
| Shed or equipment pad | Optional | 4 to 6 in | Extend 1 ft past the footprint |
Planning guidance. Wisconsin DOT's standard driveway detail, for example, uses 6 inches of dense base aggregate under 2 to 3 inches of asphalt and notes the base "may be increased for clay subgrades."
A quick lookup for the default crusher run settings, before waste: tons per 100 sq ft is 2.31 at 4 inches, 3.47 at 6, 4.63 at 8, 5.79 at 10 and 6.94 at 12. For #57 stone the same figures are 1.90, 2.85, 3.80, 4.75 and 5.70.
Subgrade Prep, Fabric and Layering
- Strip to firm soil. Remove topsoil, roots and organic material, then compact and grade the subgrade so water drains away, usually about 2% cross slope. Dig out soft spots and replace them with stone rather than bridging over them.
- Use geotextile on soft or clay soils. Without a separator, traffic and moisture pump fines up into the stone and push stone down into the mud, which thins the effective base. A training module prepared for the Local Technical Assistance Program states that a separation geotextile can raise the allowable bearing capacity of the subgrade by 40% to 50% where the subgrade CBR is 3 or more, and that on weaker soils (CBR under 3) a stabilization geotextile or geogrid adds more. Overlap rolls 1 to 1.5 ft on ordinary soil and 2 to 3 ft on very soft soil (CBR 1 to 2). In one example the fabric cost about the same as one inch of aggregate.
- Put the bigger stone at the bottom. On soft ground a common build-up is 4 to 6 inches of coarse clean stone (#2, #3 or #4 size) on fabric, then 4 to 6 inches of dense-grade on top. The dense-grade fills the surface voids and gives the paver a tight, smooth surface. Calculate each layer separately with its own material setting.
- Compact in lifts. Spread and roll 4 to 6 inches at a time with a plate compactor, or thicker with a heavy vibratory roller. Dense-grade compacts best slightly damp; dry stone stays loose and soaked stone pumps.
- Extend the base past the edge. Run the stone 6 to 12 inches wider than the asphalt so the edges are supported. Add that width to your measurements.
Worked Examples
Example 1: Single-car driveway, crusher run
12 × 50 ft = 600 sq ft at 6 inches compacted. Compacted volume 600 × 6 ÷ 12 ÷ 27 = 11.11 yd³. Loose with 25% allowance: 13.89 yd³. With 5% waste: 14.58 yd³ × 1.5 = 21.9 tons. That is two 14-ton tandem loads, or one 20-ton tri-axle plus about 2 tons.
Example 2: Two-layer pad on clay
A 30 × 60 ft (1,800 sq ft) truck turnaround on clay gets fabric, then 6 inches of #3 clean stone and 4 inches of dense-grade. Bottom layer, using Custom at 1.4 t/yd³ and 10%: 33.33 yd³ compacted, 38.50 yd³ to order with 5% waste, 53.9 tons. Top layer at the crusher run defaults: 22.22 yd³ compacted, 29.17 yd³ to order, 43.8 tons. Total 97.7 tons, or five tri-axle loads at 20 tons.
Example 3: Parking lot with a price
1,000 sq yd (9,000 sq ft) at 8 inches of dense-grade. Compacted volume 222.22 yd³, loose 277.78 yd³, with 5% waste 291.67 yd³ × 1.5 = 437.5 tons, or 22 tri-axle loads. At $28 per ton delivered, the stone costs about $12,250.
What Does Base Stone Cost?
HomeGuide's price survey puts road base at about $18 to $31 per ton, crush and run at $24 to $34 per ton, crushed concrete at $11 to $53 per ton and recycled asphalt millings at $10 to $27 per ton, with delivery adding about $10 to $25 per ton. Small orders cost much more per ton. Enter your quote in the price field to see the material cost, and use the driveway cost calculator for the full job including asphalt, labor and grading.
Tips Before You Order
- Ask how the quarry converts yards to tons. Some quote loose yards, some quote in-place yards. If the factor already accounts for compaction, set the allowance to 0%.
- Check truck size with the hauler. Federal limits on the Interstate are 20,000 lb on a single axle and 34,000 lb on a tandem, and states set their own limits on other roads. In practice a tandem dump hauls about 13 to 15 tons of stone and a tri-axle about 18 to 25 tons.
- Order the bottom layer first. Weather and soft spots can change how much coarse stone you need. Measure again before ordering the top layer.
- Pair it with the asphalt. The asphalt calculator gives the hot mix tons for the same area, and the asphalt tonnage calculator handles multiple lifts. If you are thinking about a recycled surface instead, see the asphalt millings calculator.
Related Calculators
Frequently Asked Questions
How much gravel do I need for an asphalt driveway base?
Most car driveways use 6 to 8 inches of compacted crushed stone. Multiply square feet by depth in inches and divide by 324 to get compacted cubic yards, add about 25% for compaction and 5% for waste, then multiply by about 1.5 tons per yard. A 600 sq ft driveway at 6 inches needs roughly 22 tons of crusher run.
How many tons of crushed stone are in a cubic yard?
Usually 1.35 to 1.75 tons per loose cubic yard. Clean stone like #57 is at the low end, around 1.4, and dense-grade base with fines is higher, around 1.5 to 1.75. Once compacted, dense-grade can weigh 1.8 to over 2 tons per cubic yard.
How much does crusher run compact?
Typically 15% to 35% more loose material is needed than the compacted volume. Penn State's dense-graded road aggregate goes from 8 inches loose to 6 inches compacted, which needs 33% extra. Clean #57 stone compacts much less, about 5% to 15%.
What is the best gravel for under asphalt?
Dense-graded crushed stone (crusher run, DGA, road base, 21A or your state's equivalent) is the usual choice because the fines lock the stone together into a firm, smooth surface. On soft soil, many contractors put coarser clean stone underneath and dense-grade on top.
Do I need fabric under a gravel driveway base?
On clay, wet or soft soil, a separation geotextile is cheap insurance: it stops the subgrade mud from mixing into the stone. On firm, sandy, well-drained soil it is often skipped. Overlap the rolls 1 to 1.5 feet, more on very soft ground.
How many tons of gravel does a dump truck hold?
A tandem-axle dump truck usually carries about 13 to 15 tons of stone and a tri-axle about 18 to 25 tons, depending on the truck's empty weight and state weight laws. Ask your hauler for their legal payload and enter it in the calculator.
Sources
- Penn State Center for Dirt and Gravel Road Studies, Driving Surface Aggregate technical bulletin (2025) (8 in loose compacts to 6 in; order 0.04 tons per sq ft).
- Wisconsin Department of Transportation, Standard Detail Drawing 9A15, Driveways (6 in base aggregate dense, increased for clay subgrades).
- Kokosing Materials, Aggregate tonnage calculator (cubic yards × 1.65 for clean stone, × 1.75 for base materials).
- Hello Gravel, product specifications (road base and crushed concrete about 2,800 lb per yd³, millings about 2,500 lb).
- FHWA, Reclaimed Concrete Material: Granular Base (FHWA-RD-97-148; lower compacted unit weight, CBR 90 to 140+).
- Geosynthetic Materials Association for LTAP, Introduction to Geosynthetics in Transportation, Module 1 (separation, bearing capacity, overlaps).
- FHWA, Questions and Answers About Vehicle Size and Weight (20,000 lb single axle, 34,000 lb tandem, 80,000 lb gross).
- Hello Gravel, Dump truck weight capacity guide (tandem about 13 to 15 tons, tri-axle 18 to 25 tons).
- HomeGuide, Gravel prices (road base, crush and run, crushed concrete and millings per ton).
Last updated: October 2026 · How we calculate