What do crushed stone size numbers mean?

They are gradation classes from ASTM D448 (mirrored by AASHTO M 43): each number defines which sieves the stone must pass and be retained on. Counterintuitively, smaller numbers mean bigger stone — #1 runs 2 to 4 inches while #10 is screenings that pass a 3/8 inch sieve. Two-digit numbers like #57 are blends spanning two single-size classes.

What size is #57 crushed stone?

#57 is a blend graded from about 3/4 to 1 inch — it passes a 1 inch sieve, with allowance up to 1 1/2 inches, and is retained above the #4 sieve. It is the most-stocked size in North America because it drains freely, handles easily, and works for French drains, concrete aggregate, driveway top layers and pipe backfill alike.

Crusher run (also called dense-graded aggregate, road base, ABC or #411-type blends depending on region) is crushed stone with the fines left in — everything from dust up to a 3/4 or 1 1/2 inch top size. It is not a single ASTM D448 number. The fines let it compact into a near-solid layer, which is exactly what a base course needs and exactly what a drainage layer must avoid.

What is #10 crushed stone?

#10 is screenings or stone dust — the fine fraction passing the 3/8 inch sieve, down to dust. It compacts hard and screeds flat, which makes it the standard leveling bed under pavers and a good topping for hard-packed paths. It does not drain; never use it where water must pass.

Which crushed stone size is best for a driveway?

Two sizes, in layers: crusher run for the compacted base (4 inches per lift), and either more crusher run or #57 as the surface. Large open stone like #2 or #3 works as a first lift over soft subgrade. A driveway made only of clean large stone never locks together; one made only of screenings turns to mud.

Are crushed stone sizes the same at every quarry?

The number system is standardized but regional names are not — one yard's crusher run is another's ABC, road bond or dense-graded base. When it matters, skip the nickname and confirm the gradation: ask whether the product meets ASTM D448 or AASHTO M 43 for the size number you need, and request the sieve-analysis sheet for base or concrete work.

Gravel · Crushed Stone

Crushed stone sizes, decoded

#1, #57, #8, #10 — the numbers are a sieve-based code from ASTM D448, and once you can read it, every quarry price list makes sense. Smaller number, bigger stone.

Contents

1.The size chart
2.How the numbering system works
3.The workhorse sizes
4.Crusher run and screenings
5.Matching a size to the job

The size chart

Nominal ranges per ASTM D448 / AASHTO M 43 size classes. Regional names vary; the numbers do not.
Size number	Nominal range	Primary uses
#1	2–4 in	Culvert armor, fill over very soft ground, erosion apronsThe largest standard class — machine-placed only
#2	1 1/2 – 2 1/2 in	Construction entrances, first lift over mud, heavy-truck baseBridges soft subgrade where smaller stone would sink
#3	1–2 in	Railroad ballast, dry wells, drainage beds under slabs
#5	3/8 – 1 1/2 in	Road base blends, paver sub-baseOften specified in DOT base courses
#57	3/4 – 1 in blend	French drains, concrete aggregate, driveway surface, pipe backfillThe all-purpose size — most-stocked class in North America
#8	3/8 – 1/2 in	Pipe bedding, asphalt mixes, walkway toppingAngular counterpart to pea gravel
#10	Dust – 3/8 in	Paver leveling beds, path topping, joint fillerScreenings / stone dust — compacts hard, does not drain
Crusher run	Dust – 3/4 or 1 1/2 in	Compacted base for driveways, roads, sheds and patiosDense-graded blend with fines — not an ASTM number

How the numbering system works

ASTM D448 defines each size class by a pair of sieves: nearly all of the stone must pass the upper sieve and be retained on the lower one. The classes were numbered from coarse to fine, which is why the scale runs backwards — #1 is the biggest stone and #10 is dust. Two-digit designations are blends: #57 spans the #5 and #7 classes, #67 spans #6 and #7, and so on. AASHTO M 43 adopts the same gradations for road and bridge work, so a DOT spec and a quarry ticket are speaking the same language.

The workhorse sizes

Three products cover the vast majority of residential orders. #57 is the default clean stone: big enough to leave drainage voids, small enough to shovel, rake and walk on. It is the specified aggregate in most ready-mix concrete and the standard fill around French-drain pipe. #8 is the fine clean stone — the angular cousin of pea gravel — used where a smaller, tighter surface matters: pipe bedding, asphalt mixes and walkways that feel better underfoot. Crusher run is the base material: it does nothing decorative and everything structural. If a project has layers, crusher run is almost always the bottom one. See crushed stone best uses for the full size-to-job matrix.

Crusher run and screenings

The two fines-heavy products confuse buyers most. Crusher run is a full gradation — dust through 3/4 inch or larger — that compacts to about 140 lb/ft³ and behaves almost like weak concrete once rolled. Screenings (#10 / stone dust) are only the fine fraction: they screed dead flat and pack hard, which is why paver installers level with them, but a thick layer holds water and pumps into mud under load. Rule of thumb: crusher run in structural lifts, screenings in a thin finishing bed, never the reverse.

Matching a size to the job

Choosing comes down to two questions. Does water need to pass? Then use clean stone — #57 for most drains, #3 for high-flow beds and dry wells, #8 around small pipe. Does the layer need to carry load? Then use dense-graded — crusher run in 4 inch compacted lifts, with #2 or #3 beneath it if the subgrade is soft. Decorative surfaces sit in between: #8 and #57 both walk well, while anything larger is strictly for machines and ballast. When two sizes both work, buy the one your nearest quarry stocks deepest — it will be cheaper per ton and easier to match on a top-up later.

Size questions

Keep reading

Sources & references

[1]ASTM D448: Standard Classification for Sizes of Aggregate — ASTM International, 2017
[2]AASHTO M 43: Sizes of Aggregate for Road and Bridge Construction — AASHTO, 2018
[3]The Aggregates Handbook, 2nd ed. — National Stone, Sand & Gravel Association, 2013