Understanding Aggregate Sizes: #57, #2, Crusher Run & More Explained

Walk into an aggregate supplier and you'll hear terms like "#57 stone," "#2 rock," "crusher run," and "3/4 minus." If you're not in the industry, it sounds like a secret code.

This guide decodes aggregate sizing so you can order exactly what you need.

How Aggregate Sizing Works

Aggregate sizes in the U.S. follow ASTM (American Society for Testing and Materials) and state DOT specifications. The numbering system refers to the sieve sizes used to sort material.

Key point: The numbers don't directly indicate size—they're specification designations. A higher number doesn't always mean larger stone.

Common Aggregate Sizes

The Most Popular Sizes

| Size Designation | Actual Size Range | Common Names | |-----------------|-------------------|--------------| | #57 | 3/4" to 1" | Three-quarter, drainage stone | | #67 | 3/4" to #4 sieve | Pea gravel size (with fines) | | #8 | 3/8" to #16 sieve | Screenings, chip | | #2 | 1.5" to 3" | Two-inch, large drainage | | #1 | 2" to 4" | Rip rap (small) | | 3/4" minus | Up to 3/4" | Crusher run, dense grade | | 1/2" minus | Up to 1/2" | Fine crusher run | | Crusher fines | Sand-sized | Screenings, stone dust |

#57 Stone (3/4" to 1")

The workhorse of the aggregate world.

Characteristics:

• Nominal size: 3/4" to 1"
• Clean (no fines)
• Angular (crushed) or rounded (river rock)
• Drains well

Best Uses:

• French drain aggregate
• Concrete mix aggregate
• Drainage layers
• Decorative ground cover
• Pipe bedding
• Base for pavers (with compaction)

Not Good For:

• Driveways (unless compacted surface over)
• Walking surfaces (angular stone is rough)
• Compacted base (no fines to bind)

#2 Stone (1.5" to 3")

Large drainage and base material.

Characteristics:

• Nominal size: 1.5" to 3"
• Clean (no fines)
• Very angular
• Maximum drainage capacity

Best Uses:

• Drainage ditches
• Large French drains
• Driveway base (first layer)
• Erosion control
• Retaining wall backfill
• Foundation drainage

Not Good For:

• Surface layer (too rough)
• Small pipe bedding (won't surround)
• Foot traffic areas

#1 Stone / Rip Rap (2" to 4"+)

Heavy-duty erosion control.

Characteristics:

• Large individual stones
• Angular and interlocking
• Stays in place on slopes
• Available in larger sizes for severe applications

Best Uses:

• Slope stabilization
• Stream bank protection
• Culvert outlets
• Dam protection
• Coastal erosion control

Not Good For:

• Anything requiring compaction
• Residential drainage (overkill)
• Pedestrian areas

#67 Stone (3/4" with fines)

Versatile mid-size aggregate.

Characteristics:

• 3/4" maximum with some smaller particles
• Compacts moderately well
• Good drainage with some stability

Best Uses:

• Asphalt production
• Concrete mix
• Moderate drainage applications
• Base layer (with additional top layer)

#8 Stone / Chips (3/8" to 1/2")

Small aggregate for specific uses.

Characteristics:

• Pea-sized particles
• Clean or with minimal fines
• Good walkability

Best Uses:

• Pea gravel alternative
• Decorative applications
• Pipe bedding (small diameter pipes)
• Pathway surface
• Playground surfacing

Not Good For:

• Vehicle traffic (migrates)
• Slopes (rolls downhill)
• Compacted base

Crusher Run / Dense Grade (3/4" minus)

The best base material available.

Characteristics:

• Mix of 3/4" stone down to fines
• Angular particles
• Compacts extremely well
• Creates solid, stable surface

Best Uses:

• Driveway base (primary choice)
• Parking lot base
• Road base
• Building pad preparation
• Under concrete slabs
• Equipment pads

Not Good For:

• Drainage (fines block water flow)
• Decorative applications (gray, dusty)
• French drains

Stone Dust / Screenings

The finest aggregate product.

Characteristics:

• Sand-like particles
• Byproduct of crushing operations
• Compacts very hard when wet

Best Uses:

• Paver setting bed
• Leveling layer
• Filling joints
• Horseshoe pits
• Mixing with soil

Not Good For:

• Drainage (none)
• Standalone base (needs larger stone below)
• Wet areas (turns to paste)

Choosing the Right Size

For Drainage Projects

| Application | Recommended Size | |-------------|-----------------| | French drain | #57 (3/4" clean) | | Curtain drain | #57 or #2 | | Foundation drain | #57 | | Large drainage channel | #2 or #1 | | Dry well | #57 or #67 |

Key: Use CLEAN (washed) aggregate. Fines clog drainage.

For Driveways

| Layer | Recommended Size | |-------|-----------------| | First layer (base) | #2 or 1.5" crusher run | | Second layer | 3/4" crusher run | | Surface layer | 3/4" minus or #57 (topped) |

Key: Use angular stone with fines (crusher run) for compaction.

For Base Under Structures

| Structure | Recommended Size | |-----------|-----------------| | Concrete slab | 3/4" crusher run (compacted) | | Paver patio | 3/4" crusher run + stone dust | | Retaining wall | #57 (backfill) + crusher run (base) | | Shed pad | 3/4" crusher run |

For Erosion Control

| Severity | Recommended Size | |----------|-----------------| | Light runoff | #57 or #2 | | Moderate flow | #2 or #1 | | Heavy flow | #1 or large rip rap | | Stream/river | Class II or III rip rap |

Recycled Concrete Aggregate (RCA) Sizing

RCA is available in the same size designations:

| RCA Product | Equivalent Virgin Size | |-------------|----------------------| | 3/4" RCA | #57 equivalent | | 3/4" minus RCA | Crusher run equivalent | | 1–2" RCA | #2 equivalent | | 2–4" RCA | #1 / rip rap equivalent | | RCA fines | Screenings equivalent |

RCA typically costs 30–40% less than virgin aggregate while performing identically for most applications.

Comparing Weight and Coverage

Weight per Cubic Yard

| Material | Tons/Cubic Yard | |----------|----------------| | Crushed stone (most) | 1.35–1.45 | | Crusher run | 1.45–1.55 | | Sand | 1.35–1.40 | | RCA | 1.35–1.45 | | River rock | 1.30–1.35 |

Coverage per Ton

| Depth | Square Feet/Ton | |-------|----------------| | 1" | 200–240 | | 2" | 100–120 | | 3" | 65–80 | | 4" | 50–60 |

How to Order

Information to Provide

1. Size — Be specific (#57, 3/4" minus, etc.)
2. Clean or with fines — Drainage or compaction?
3. Quantity — Tons needed
4. Delivery address — Access considerations
5. Timing — When you need it

Questions to Ask

• "Is this clean or does it have fines?"
• "What's the actual gradation?"
• "Do you have RCA in this size?"
• "What's the minimum order for delivery?"
• "Can I get a sample before ordering?"

Common Ordering Mistakes

Mistake 1: Wrong Type for Application
Ordering drainage stone for a driveway (won't compact) or crusher run for a French drain (won't drain).

Mistake 2: Not Specifying Clean vs. Dirty
"3/4 stone" could mean clean #57 OR 3/4" minus with fines. Be explicit.

Mistake 3: Underestimating Quantity
Use our Gravel Calculator. Always order 10% extra.

Mistake 4: Ignoring Delivery Access
A tri-axle dump truck can't navigate tight driveways. Know your limitations.

Mistake 5: Confusing Regional Names
Terms vary by region. Verify by actual size specification, not just name.

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Need aggregate for your project? Smoky Mountain Sand & Gravel carries all standard sizes in both virgin and recycled options. Contact us at (865) 999-0857 for pricing and availability.