Among all aggregate stone materials, crushed stone and gravel are the two most widely used—yet, many contractors and homeowners don't understand the difference.
Choosing the wrong rock sizes not only wastes money but can lead to crushed gravel driveway washouts, drainage failures, or a yard full of weeds.
Today, we're breaking down the US-standard crushed stone size chart (ASTM) to help you shop like a pro. This guide will save you time and money.
What is crushed stone and what is gravel?
We often refer to small rocks on the ground generally as "gravel", but in engineering and purchasing, crushed stone and gravel are two completely different things.
Crushed stone (Man-made aggregate)
Crushed stone is a man-made aggregate. It is produced by feeding large rocks—such as limestone, granite, basalt, or dolomite—into industrial crushers (Jaw Crushers, Cone Crushers, Impact Crushers). After mechanical crushing, these rocks are screened into uniform stone sizes.
Gravel (Natural aggregate)
Gravel is a naturally formed aggregate. Riverbeds, glacial deposits, and ancient watercourses are typical sources. Unlike crushed stone, gravels are rounded or semi-rounded, have smoother surfaces, and come in varying sizes.
Crushed stone vs. Gravel: Key differences
Crushed stone has angular, sharp edges that lock together tightly. If you need compacted gravel for a hard, stable base, you must use crushed stone.
Gravel stone is smooth and rounded, allowing water to flow quickly through the gaps. However, because it acts like marbles, it slides easily under weight. This makes gravel superior for drainage and aesthetics.
| Feature | Crushed stone | Gravel |
| Source | Mechanicaly crushed rock | Natural weathering/Riverbeds |
| Shape | Angular, sharp edges | Rounded, smooth |
| Best uses | Concrele, Asphalt, Road base, Structural layers | Drainage, Landseaping, Decor |
| Drainage | Good (depends on grade) | Excellent |
| Consistency | Highly uniform, precise aggregate size | Gravel sizes vary by source |
| Interlocking | High (compacted gravel holds shape) | Low (easy to move) |
Crushed stone size chart & ASTM grades
In the US, crushed stone grades are numbered according to the ASTM C33 standard. Generally, the smaller the number, the larger the stone. #57 stone and #67 stone are the most widely used aggregate sizes in North America.
1. Coarse aggregates: the heavy lifters
- #1 Stone (2-4 inches): About the size of a fist or a large mango.
- #3 Stone (1/2 - 2 inches): Similar to the size of a tennis ball or egg.
2. Medium stone: the "all-rounder"
- #57 Stone (3/4 inch): About the size of a Quarter or Nickel. It is the most common stone size in the US. It is considered "Clean Stone," meaning it has been washed and contains no dust.
This is the gold standard rock for driveway drainage and is the mandatory material for French Drains. The large gaps allow water to flow through instantly.
3. Fines & mixes: the driveway "King"
- #411 stone / Crusher run / Quarry process: This is a mixture containing #57 stone plus fine stone dust.
This is the best size gravel for driveway surfaces. The large stones provide the skeleton, while the dust fills the voids. When wet and rolled, it becomes compacted gravel that is nearly as hard as concrete.
4. Small aggregates: leveling & filling
- #8 Stone (1/8 - 3/8 inch): Pea-sized but angular.
- #10 Stone / Stone dust: Screenings that look like coarse sand.
| Grade | Particle size | Common uses |
| #1 | 2–4 in (50–75 mm) | Heavy road base, erosion control |
| #3 | ½–2 in (12–50 mm) | Railroad ballast, drainage systems, driveway base |
| #5 | 1 in or smaller (12–25 mm) | Road base, paver base, residential driveways |
| #8 | 3/8 in (5–9.5 mm) | Concrete mixes, asphalt, decorative landscaping gravel |
| #10 | Stone dust / screenings (<5 mm) | Paver base, concrete blocks, “crusher run” for patios and walkways |
| #57 | ¾ in (9.5–25 mm) | Drainage, concrete and asphalt base |
| #67 | ¾ in, smaller than #57 (<19 mm) | Concrete slab base, roads, highways |
| #411 | Mix of #57 + #10 | Compact, stable base for driveways, parking pads, construction foundations |
Crushed stone size chart
Common types of gravel (natural)
Aside from crusher stone, here are the most common types of gravel found in nature.
1. Pea gravel
Pea gravel typically measures about 3/8 inch and consists of small, smooth, rounded stones. It often comes in mixed natural colors like brown, gray, and white. It's cheap and comfortable to walk on, and offers excellent drainage.
2. River pebbles
Typically 1 to 6 inches. Naturally rounded and smooth. Excellent for decorative landscaping and dry creek beds to prevent erosion.
3. Bank gravel
Unprocessed construction gravel mixed with sand and dirt directly from the bank. Because it's inexpensive and widely available, it's often used for large fill projects, road embankments, and sub-base work.
4. Beach/sea gravel
Beach gravel features smooth stones shaped by ocean waves. Great for premium landscaping but must be washed to remove salt before use near concrete.
5. Decorative gravel
Decorative gravel includes materials like lava rock, marble chips, and slate, chosen mainly for their color and texture for use in gardens and pathways.
Which type of stone should I buy?
- Driveway base layer: Use #3 or #4 stone. Only large rock sizes can support vehicle weight on top of mud/soil.
- Driveway surface layer: Use crusher run. It must contain dust! Only mixes with dust can form compacted gravel that won't shift under tires.
- French drain: Use #57 stone (washed). It must be clean. Stone dust will clog the drain pipe, so washed gravel is required.
- Patio or paver base: Use crusher run + stone dust. Compacts into a solid, stable platform that prevents pavers from sinking.
- Garden pathways: Use pea gravel. It looks great, has a pleasant crunch underfoot, and is comfortable to walk on.
Professional crushing & screening solutions
Have you ever wondered: Why is some crushed stone uniform with great interlocking, while others are flaky and brittle? Why is some #57 stone clean, while others are full of dirt?
The difference lies in the crushing and screening equipment.
As a core part of aggregate stone production, high-quality equipment determines the stone measurement accuracy and particle shape. FTM Machinery specializes in crushing and screening solutions, providing top-tier equipment for quarries, mines, and construction recycling projects.
How we define "quality aggregate" production?
1. Efficient crushing
Our Jaw Crushers handle the primary stage, easily processing large quarry rocks.
Cone Crushers and Impact Crushers focus on secondary and tertiary crushing. Through optimized cavity design, they produce high-quality aggregate (like #57 stone, #67 stone) with a cubic shape, significantly reducing needle-like flakes to meet strict ASTM standards.
2. Precise screening
Grading gravel sizes must be accurate. Our Vibrating Screens use advanced excitation technology to ensure every stone is sent to the correct pile. Whether it's fine #10 stone dust or standard #57 stone size for drainage, our equipment ensures precise separation.
3. Mobile solutions
We offer Mobile Crushing Stations. No concrete foundation is required—drive the equipment directly into the quarry or demolition site. Convert waste concrete or rock immediately into usable crusher run or base material.
Whether you need to upgrade an existing quarry line or are looking for efficient mobile crushing solutions, FTM Machinery provides customized support. Contact us
