Number 57 stone is a precisely graded crushed aggregate defined by ASTM standard C33. The “57” designation refers to the combination of ASTM sieve sizes 5 and 7 — material that passes through a 1-inch screen but is retained on a No. 4 screen, yielding pieces that typically range from 3/4 inch to 1 inch in diameter. Unlike pea gravel or river rock, which are smooth and rounded from water action, #57 stone is angular and jagged, produced by crushing quarried parent rock — most commonly limestone, dolomite, or granite — through heavy jaw-and-cone crusher equipment at an aggregate quarry.
That mechanical origin gives #57 its primary structural advantage. The fractured faces of each piece lock against neighboring stones when a load is applied, creating an interlocking matrix that resists lateral migration and holds its position under repeated stress. Civil engineers and site contractors specify #57 stone routinely for pipe bedding, concrete drainage structures, and driveway base courses precisely because it performs predictably under vibration and doesn’t shift the way rounded aggregate can. When you see a crew filling a trench around a perforated drainage pipe, the clean, open-textured gray stone going in almost certainly meets the ASTM 57 specification.
The open gradation is both a strength and a limitation. Because #57 stone contains almost no fine particles, water passes through it rapidly without ponding. That same openness means it does not lock into an absolutely rigid surface the way a dense-graded crusher run does — which makes it ideal as a drainage medium or structural base under pavers or concrete, but not the right finishing material for a driveway surface you want to drive on without kicking stones.
How to Calculate How Much #57 Stone You Need
The volume-to-weight formula is the same for all aggregate materials. Find cubic feet first: length (ft) × width (ft) × (depth in inches ÷ 12). Convert to cubic yards by dividing by 27. Multiply cubic yards by 1.39 tons — the weight conversion for #57 stone at 103 lb/ft³.
Worked example: a 30 ft × 10 ft driveway base at 6 inches deep.
- Cubic feet: 30 × 10 × (6 ÷ 12) = 30 × 10 × 0.5 = 150 cu ft
- Cubic yards: 150 ÷ 27 = 5.56 cu yd
- Tons: 5.56 × 1.39 = 7.73 tons
Rounding up to 8 tons leaves a small reserve for any undulations in the excavated subgrade or high spots that need extra fill before final grading.
#57 Stone Coverage at Common Depths
Coverage figures below are based on 103 lb/ft³ (1.39 tons per cubic yard). Because #57 stone is open-graded, a small percentage of voids exist within the placed layer, meaning actual material consumption may run slightly higher than these numbers suggest for very precise applications.
| Depth | Coverage per ton | Coverage per cubic yard |
|---|---|---|
| 1 inch | 233 sq ft | 324 sq ft |
| 2 inches | 117 sq ft | 162 sq ft |
| 3 inches | 78 sq ft | 108 sq ft |
| 4 inches | 58 sq ft | 81 sq ft |
For French drain trenches, coverage is better expressed as linear feet per ton at a given trench width and backfill depth — use the calculator above with your trench dimensions to get an accurate trench estimate.
How Much #57 Stone for Common Projects
Driveway base — 40 ft × 12 ft at 4 inches deep
Volume: 40 × 12 × 0.333 = 160 cu ft → 5.93 cu yd → 5.93 × 1.39 = 8.24 tons. Nine tons is a practical order quantity for this project — the overage covers minor grade corrections and ensures the base layer reaches full depth at the edges where trucks will track.
French drain trench — 60 ft long × 1.5 ft wide × 2 ft deep
Volume: 60 × 1.5 × 2 = 180 cu ft → 6.67 cu yd → 6.67 × 1.39 = 9.27 tons. For this trench, plan for 10 tons. Drainage pipe occupies a small fraction of the trench volume, and the stone needs to fully surround the pipe and fill to grade above it for the drain to function correctly.
Parking pad base — 20 ft × 20 ft at 6 inches deep
Volume: 20 × 20 × 0.5 = 200 cu ft → 7.41 cu yd → 7.41 × 1.39 = 10.3 tons. A parking pad that handles pickup trucks and SUVs needs the full 6-inch base depth. Ordering 11 tons accommodates the typical 5–8% settlement that occurs after a few rain cycles.
Drainage area behind retaining wall — 25 ft × 2 ft at 4 inches deep
Volume: 25 × 2 × 0.333 = 16.7 cu ft → 0.62 cu yd → 0.62 × 1.39 = 0.86 tons. One ton handles this drainage strip with material to spare for building up the stone slightly above the pipe outlet elevation to encourage positive drainage away from the wall.
Buying and Delivery Tips
Number 57 stone is sold almost exclusively by the ton at aggregate quarries and landscape supply yards. Bagged versions exist at home centers but carry a steep price premium per ton and become impractical above a half-cubic-yard quantity. Most residential drainage and driveway projects fall in the 5–15 ton range, which is well within what a standard 10-ton single-axle dump can handle in one trip.
Regional naming varies more for #57 than for almost any other aggregate. Terms like “57 crushed stone,” “1-inch clean stone,” “pea-sized drainage stone,” and “open-graded aggregate” all typically refer to material meeting the ASTM C33 #57 gradation. Confirming the sieve specification — passes 1 inch, retained on No. 4 — takes thirty seconds on the phone and prevents receiving a different gradation that doesn’t drain the way you expect.
Because #57 is open-graded, compaction loss runs 5–8% rather than the 15–20% typical for dense-graded base material. Running a plate compactor over placed #57 before adding a top course helps seat the aggregate and identify any soft subgrade spots that need remediation before you pour concrete or set pavers. Pricing typically falls in the $25–$50 per ton range, with limestone-based material at the lower end and granite or trap rock at the higher. Delivery minimums and fuel surcharges vary by supplier, so combining all your stone needs into a single order saves on logistics costs.