Gravel & Crushed Stone Size Chart: #57, #21A, Crusher Run & More
The homeowner's reference for every common gravel size — what it looks like, whether it compacts or drains, which projects it suits, and exactly what to say at the quarry.
By the Cubic Yard Calculator team · Last updated October 2026
The short answer
Almost every gravel decision comes down to two families. Clean crushed stone (#57, #8, #3) has the dust washed out: it drains beautifully but only locks together moderately, so it is the right call anywhere water must pass through. Stone with fines (crusher run, 21A, quarry process, dense grade) keeps its rock dust: it compacts into a hard, pavement-like crust, but drains poorly — so it is the right call anywhere tires or feet need a firm surface. The rule of thumb: drive on it → fines; drain through it → clean. One more thing to know before you shop: gravel names are regional. 21A, crusher run, quarry process, and dense grade are often the exact same bin of stone wearing different labels — the chart below translates them for you.
The master chart: every common size, decoded
Find the stone, read across for what it looks like, how it behaves, and where it belongs. The last column gives you the exact words to use when you call the quarry.
| Stone | Typical size | What it looks like | Compacts? | Drains? | Best projects | What to ask the quarry for |
|---|---|---|---|---|---|---|
| #57 stone | ¾–1 in | Chunky angular gray rock, washed clean | Moderately — locks in place but stays open | Excellent | French drains, driveway middle layer, drainage beds | “#57 stone” or “1-inch clean stone” |
| #21A / crusher run | ¾ in minus + fines | Mixed chips and rock dust — packs like pavement | Excellent — the best binder on this chart | Poor to fair (fines block the voids) | Driveways, shed bases, RV pads | “Crusher run”, “21A”, or “¾-inch minus” |
| #8 stone | ⅜ in chips | Small angular chips, washed clean | Moderately, in thin layers | Excellent | Paver bedding and joints, drainage trenches, fire-pit areas | “#8 stone” or “⅜-inch chips” |
| Pea gravel | ⅜ in, rounded | Smooth colorful river pebbles — the pretty one | No — round stones roll and migrate | Excellent | Walkways, patios, fire-pit areas | “Pea gravel” |
| #3 / #4 stone | 1–3 in | Big angular chunks — looks like riprap's little sibling | No — bridges soft soil instead | Excellent | Deep driveway/road bases, retaining-wall drainage, construction entrances | “#3 stone” or “2-inch clean” |
| Quarry process / dense grade | ¾ in minus + fines | Near-twin of crusher run, blended to a spec | Excellent | Poor to fair | Driveways, shed bases, path bases | “Quarry process”, “Item 4”, or “dense graded aggregate” |
Regional names: same bin, different label
Gravel naming follows quarry tradition, not national standards, so the same material can sound like four different products. When you hear 21A (Mid-Atlantic), crusher run (Southeast), quarry process or Item 4 (New York / New England), dense grade (Midwest), or ¾-minus (Pacific Northwest), you are almost always hearing about ¾-inch crushed stone with fines included — the compacting, driveway-grade material. #57 is the nationwide term for 1-inch clean stone with the fines washed out. If a quote uses a name you do not recognize, ask the one clarifying question: “Is that with fines, or washed clean?” The answer tells you everything about how it will behave.
The two-question buying shortcut
Staring at the chart and still unsure? Answer these in order.One: will it be driven or walked on heavily? If yes, you need fines that bind — crusher run, 21A, quarry process, or dense grade. A firm top layer is non-negotiable for driveways, RV pads, and shed bases. Two: does water need to pass through it? If yes — French drains, drainage beds, retaining wall backfill, fire-pit surrounds — you need clean stone with no fines: #57, #8, or #3. Mixing the two up is the most common gravel mistake: fines under a downspout trench clog it into a pond, and clean stone under a car scatters like marbles.
What to tell the quarry (exact script)
Quarries sell by the ton and quote faster when you sound like you know the drill. Say: “I need [quantity] tons of [stone name], delivered to [address].” To get the quantity, compute cubic yards first — length × width × (depth in inches ÷ 12) ÷ 27 — then multiply by 1.4 (a cubic yard of gravel weighs about 2,800 lbs, or 1.4 tons). Then confirm three things: that the price is delivered per ton (hauling is where quotes balloon), whether a tailgate-spread is possible on your site, and that a tri-axle can reach the dump spot (about 12 feet wide and 14 feet of overhead clearance). Always ask for loose stone, not bags — bagged gravel costs several times more per ton and only makes sense for patching.
Ordering math: from this chart to a tonnage quote
Once the chart has told you which stone, the order is simple arithmetic. Cubic yards = length × width × (depth in inches ÷ 12) ÷ 27. Tons = cubic yards × 1.4 (a cubic yard of gravel weighs about 2,800 lbs). Example: a 12×50 ft driveway lane at 6 inches — the standard rebuild depth — is (12 × 50 × 0.5) / 27 = 11.1 cubic yards, × 1.4 = 15.6 tons of crusher run for the top layer. Then add 10% overage for compaction loss and edge spill, and you have your quote number: about 17 tons. Build the base layer the same way with #3 stone if the soil is soft. The gravel calculator runs the same math with your dimensions in one click.
Common mistakes this chart prevents
Pea gravel driveways. It looks charming in the photos and migrates to the lawn within a month — round stone cannot lock under tires. Crusher run in drainage trenches. The fines that make it great under tires make it terrible under water; drainage stone must be washed clean. One stone for the whole build. Bases want big, clean stone (#3) that bridges soil; surfaces want fines that bind (crusher run). Ordering before asking about fines. If the quote just says “gravel,” ask whether it is with fines or washed clean — that single answer decides whether your project works.
Gravel & Stone Size Chart FAQ
Straight answers, no fluff. Then run your own numbers above.
What is the difference between #57 stone and crusher run?
#57 stone is clean, crushed rock about ¾ to 1 inch across with the dust washed out — it drains beautifully but only locks together moderately. Crusher run is ¾-inch-minus stone that still contains its rock-dust fines, so it compacts into a hard, pavement-like crust but drains poorly. Pick #57 where water must pass through, crusher run where tires or feet must drive on it.
What is 21A gravel?
21A is the Mid-Atlantic quarry term for ¾-inch crusher run — crushed stone graded from ¾ inch down to rock dust, with the fines included. It is the same material other regions call crusher run, dense grade, or quarry process. Its fines are what let it compact into a firm driving surface.
Does pea gravel compact?
No. Pea gravel's stones are rounded river rock, so they roll past each other instead of locking together — it migrates under tires and shuffles under feet. Use it for walkways, patios, and fire-pit areas where looks matter, and use crusher run for anything that must stay put.
Which gravel drains the best?
Clean angular stone with no fines drains best: #57 stone, #8 chips, and #3/#4 large stone all let water pass straight through. Avoid crusher run, 21A, quarry process, or dense grade anywhere drainage matters — their fines clog the voids that water needs.
What size gravel is best for a driveway?
Build in layers: large #3 stone (about 2 to 3 inches) for the base, #57 stone (about 1 inch) in the middle, and crusher run (¾-inch minus with fines) on top. The crushed, angular top layer locks together into the drivable surface.
How much gravel do I need for my project?
Measure length times width times depth in feet, then divide by 27 to get cubic yards. Gravel is sold by the ton, and a cubic yard weighs about 1.4 tons, so multiply your cubic yards by 1.4. The gravel calculator does this conversion automatically.
References
- Aggregate sizing: ASTM C33 aggregate gradations for #57, #8, #3/#4 and related stone sizes.
- Material densities: published bulk-material density tables cross-checked against supplier data (see /data-sources/).
- Regional product names and quarry practice: supplier listings for crusher run, 21A, quarry process and dense grade, checked October 2026.
Run your own numbers
Reading is good. Math is better. Punch your project into the free calculator and order with confidence.