Gravel sizes by number
Crushed stone is sold by screen number: the stone passed one sieve and stayed on another. Lower numbers are bigger stone. This chart covers the sizes yards actually stock — pick the size, then head to the matching calculator for tons.
| Name / number | Stone size | Best for |
|---|---|---|
| Stone dust / screenings | < 3/16″ | Setting beds, path topping, joint sweep |
| Pea gravel | ⅜″ round | Walkways, playgrounds, between steppers |
| #8 | ⅜″ crushed | Pipe bedding, walks, chip-seal |
| #57 | ¾–1″ | Driveway top course, French drains, concrete mix |
| #4 | 1–2½″ | Heavy drainage, entrance stabilization |
| #3 | 1–2″ | Driveway base lifts, culvert surround |
| #2 | 2½–3″ | Construction entrances, soft-ground subbase |
| Crusher run / road base | fines–¾″ | Compacted base under everything |
| Rip-rap | 3–12″+ | Erosion control, banks, outfalls |
What the screen numbers mean
The numbers come from the ASTM/AASHTO grading system, and they read backwards from what people expect: a stone’s size is set by which sieves it passes through and which one it stays on, and the bigger the number, the smaller the stone:
- The sieve stack: #8 passes a ⅜ in screen; #57 passes 1½ in and is caught on a #4; #4 runs 1–2½ in. The number is a screen designation, not a diameter.
- Clean vs dense-graded: clean (washed) stone is a single size with the fines removed — it drains. Dense-graded keeps everything down to dust — it compacts. This is the single most important distinction on the chart.
- Angular vs round: crushed stone locks together and holds a slope; round stone (pea, river rock) rolls and needs edging.
- Minus vs clean: “¾ minus” means ¾ in down to dust (compacts); “¾ clean” means ¾ in with the fines washed out (drains).
Which gravel size for which job?
The whole pattern behind the chart is one line: fines compact, clean stone drains. Anything with dust in it locks into a hard mat — that’s base and bedding; anything washed stays open and moves water — that’s drainage and top courses; round stone is for feet and looks, never structure. By job:
- Driveway: #3 base, crusher run middle, #57 top — priced on the gravel driveway calculator.
- Drainage / French drain: clean #57 around pipe; #4 under heavy flow. Never fines.
- Compacted base: crusher run or road base — the road base calculator handles the lifts.
- Paths & patios: pea gravel or #8 over a screenings bed; screenings on the stone dust calculator.
- Erosion control: rip-rap on banks and outfalls — the rip-rap calculator sizes it.
Gravel goes by different names in every region
The size ranges are national, set by the ASTM sieves; the names are stubbornly local, left over from decades of separate state-DOT and regional-quarry conventions. If your yard doesn’t recognize a screen number, ask for it by the alias — and if that draws a blank too, describe the size range and the use:
| Size | Also called |
|---|---|
| Screenings | Stone dust, grit, quarry dust, fines |
| #8 | ⅜″ clean, chip stone |
| #57 | Washed #57, septic / drain stone |
| Crusher run | CA-6, Class 5, 21A, DGA, road base |
| Rip-rap | Armor stone, R-3 / R-4 classes |
How to pick the right gravel size
- Name the job first — base, drainage, driveway top, or path — because the job, not the look, sets the size.
- Decide compact or drain: if it carries load, pick a dense-graded stone with fines; if it moves water, pick clean washed stone.
- Match the size to the range in Table 1 — bigger stone for base and heavy flow, smaller for surfaces and bedding.
- Translate to the local name from Table 2 so the yard knows what you want.
- Figure the tons on the gravel calculator or the material’s own page from the size and depth.
What a size chart doesn’t tell you
The chart gets you the right stone; a few things it can’t settle:
- Local stock. Not every quarry runs every screen — availability and price vary by what’s quarried nearby.
- Rock type. Limestone, granite and trap rock all come in these sizes but weigh differently — density drives the tonnage.
- Washed or not. The same number can be sold clean or with fines; say which you need.
- Depth and compaction. Size doesn’t set quantity — that’s area, depth and a base’s compaction, on the calculators.
- Angularity. Crushed holds a slope; rounded needs edging — the chart’s size range doesn’t capture shape.
Gravel size FAQ
What do gravel numbers like #57 mean?
They are screen sizes from the ASTM/AASHTO grading system — the number tells you which sieves the stone passed and stayed on. #57 passes a 1½ in screen and stays on a #4 (about ¾–1 in stone); the bigger the number, the smaller the stone.
What size gravel is best for a driveway?
Three lifts: big #3 stone (1–2 in) as the base where ground is soft, crusher run or road base as the middle, and 2–3 in of #57 (¾–1 in) on top. #57 is the classic driveway surface — big enough to stay put, small enough to walk and plow.
What size gravel for drainage?
Clean (washed, no fines) #57 is the all-purpose drainage stone for French drains and pipe bedding; step up to #3–#4 around perforated pipe under heavy flow. Never use anything with fines — the dust is what clogs fabric and pipe slots.
What size gravel for walkways?
Pea gravel (⅜ in, rounded) or #8 crushed for the surface — comfortable underfoot — over a compacted screenings or road-base layer so it doesn’t swallow shoes. Edge it; small round stone migrates.
What is crusher run?
Everything the crusher makes up to a top size — stone plus fines, usually ¾ in minus. The fines let it compact into a hard mat, which makes it a base material, not a drainage one. Regional names: CA-6, Class 5, 21A, dense-grade aggregate (DGA), road base.
What size is #57 stone?
#57 is ¾ to 1 in washed crushed stone — it passes a 1½ in sieve and is retained on a #4, with the fines screened out. It is the most common landscape and drainage stone on the yard: open enough to drain freely, small enough to shovel, rake and walk on.
What is the difference between clean and dense-graded gravel?
Clean (washed) gravel is a single size with the fines removed, so it drains and stays loose — #8, #57, #4. Dense-graded stone keeps the full range of sizes down to dust, so it compacts into a hard mat — crusher run, road base. Clean stone for drainage and top courses; dense-graded for the base under them.
Sources and standards
The size system is standardized; the names and stock are local:
- ASTM D448 / AASHTO M43: the standard sizes of coarse aggregate — the #57, #8, #4 designations and their sieve ranges.
- State DOT dense-graded specs: the crusher-run / road-base gradations and their regional names (CA-6, Class 5, 21A, DGA).
- State DOT rip-rap classes: the R-3 / R-4 armor-stone sizes for the coarse end of the chart.
- The quarry ticket: your local yard’s stock list and naming govern what you can actually buy — the size ranges don’t change.