Key Takeaways
- #57 is washed, angular crushed stone, roughly half an inch to an inch across
- The number is a size grade, not a rock type; #57 limestone and #57 granite are both #57
- Washed stone drains but does not compact; dense graded material compacts but does not drain
- Common uses: under concrete, driveway surfaces, and drainage applications
- Density is about 1.4 tons per cubic yard Aggregate Industries, or roughly 2800 pounds per cubic yard
Cubic yard is a unit of volume equal to a cube measuring 3 feet on each side, commonly used in the US for ordering gravel and other aggregates.
Density in gravel calculations refers to the weight of material per unit volume, typically measured in tons per cubic yard or tonnes per cubic metre.
#57 is washed, angular crushed stone, roughly half an inch to an inch across, with the fines screened out. It is one of the most widely stocked grades there is, and it turns up under concrete, on driveways and in drainage work.
The number is a size grade, not a rock type. A #57 limestone and a #57 granite are both #57.
What the numbers mean
The numbered grades describe what the material was screened to. Roughly:
- #3: large, about one and a half to two and a half inches. Sub base on soft ground.
- #57: half an inch to an inch. The general workhorse.
- #67: a little smaller than #57, otherwise similar in use.
- #8: small chip, an eighth to three eighths of an inch. Bedding under pavers, drainage in tight spaces.
What each grade is called, and exactly how it is screened, varies by region and by yard. If you have been specified one grade and offered another, it is worth asking what the actual screen sizes are rather than assuming the numbers mean the same thing everywhere.
The distinction that matters more than the number
Whether the fines were washed out.
Clean or washed stone, like #57, has the dust removed. Water runs straight through it. It never really compacts, because there is nothing to fill the voids between the pieces, and those open voids are the entire point when drainage is the job.
Dense graded material, like crusher run, keeps its fines. It binds and compacts into a firm, load bearing layer, and it drains poorly for exactly the same reason.
These are not interchangeable, and the price difference tempts people to treat them as if they were. Clean stone where load has to be carried gives you a surface that shifts. Dense graded material in a french drain gives you a trench that packs solid and stops draining, which is the one thing it was dug to avoid.
What #57 is good at
Under concrete. It drains, it does not hold water against the slab, and it provides a stable, free draining layer.
Driveway surfaces. Angular pieces lock together and stay put under tyres, where rounded stone rolls and scatters. It is a common surface course over a compacted base.
Drainage. Clean, open voids, decent size. It works well around pipe and as backfill behind retaining walls.
What it is not good at
Compacting. If you need a layer that binds into something solid, this is the wrong material and no amount of rolling will fix that.
Walking barefoot. It is angular stone. Comfortable is not on the list.
Holding a slope. Clean stone migrates downhill. On any real gradient it needs containment.
Weight and quantities
#57 is commonly quoted at about 1.4 tons per cubic yard, with the usual spread of 1.3 to 1.5 depending on the parent rock and the moisture. That works out to roughly 2800 pounds per cubic yard.
For an actual quantity, the crushed stone calculator covers all the numbered grades and lets you swap in your supplier’s density, which is always going to be more accurate than a published average.
Editorial note: This article is reviewed for accuracy and updated regularly. All calculations use standard industry formulas. For the latest density figures, consult your gravel supplier directly.
Frequently asked questions
What is the difference between #57 and crusher run?
#57 is washed stone with fines removed, so it drains but does not compact. Crusher run keeps its fines, so it compacts into a solid base but does not drain. Use #57 for drainage and surfaces; use crusher run for base layers that need to carry weight.
How many tons of #57 gravel do I need for a driveway?
For a typical residential driveway with a 2-inch surface layer, you need about 0.95 tons per 100 square feet. For a 20x50 foot driveway, that is roughly 9.5 tons for the surface layer alone. Use the driveway calculator to account for multiple layers and exact dimensions.
Is #57 gravel good for walkways?
#57 works for walkways but is not comfortable for barefoot use due to its angular edges. For barefoot areas, consider pea gravel or smooth river rock. For pathways with regular foot traffic, #57 provides good drainage and stability.
What does #57 mean in gravel sizes?
The number #57 refers to a specific size grade: stones roughly half an inch to an inch across. The numbered system varies by region and supplier, so always confirm the actual screen sizes with your local yard.