Gravel Sizes Explained: Which Size Do You Need?
From fine chips to large drainage stone, matched to the job
Why size matters
Gravel size affects drainage, compaction, walkability and appearance. A size that compacts well into a stable base (generally requiring a mix of particle sizes) is a poor choice for a free-draining French drain, and a large, angular drainage stone makes an uncomfortable walking surface for a garden path.
Two properties do most of the work: the size range of the stone, and whether it is 'clean' (washed, few fines) or contains fines (sand- and dust-sized particles). Clean stone leaves open voids for water to move through. Stone with fines packs those voids and locks into a hard, stable layer — but drains slowly.
How gravel sizes are named
Many US quarries use the standard size numbers from ASTM D448 (the same system appears as AASHTO M 43). Each number describes a range of sieve sizes, not a single stone size. Counter-intuitively, a smaller number means larger stone. Suppliers also use local trade names, so it's worth asking for the size number or a gradation sheet when the job depends on it.
| Name | Nominal size range | Typical uses |
|---|---|---|
| #3 stone | 2 in to 1 in | Drainage layers, stabilizing soft ground under a driveway, permeable-paver subbase |
| #57 stone | 1 in down to No. 4 sieve (~3/16 in) | French drains, drainage behind walls, permeable-paver base, concrete aggregate |
| #67 stone | 3/4 in down to No. 4 sieve | Concrete aggregate, pipe bedding, drainage |
| #8 stone | 3/8 in down to No. 8 sieve | Permeable-paver bedding layer, small drainage applications |
| Pea gravel | Rounded, about 1/4–3/8 in | Paths, play areas, decorative beds (needs edging) |
| Crusher run / dense-graded base | About 1–1½ in down to dust | Compacted driveway and slab base |
| Screenings / stone dust | No. 4 sieve down to dust | Fines for paths and fill; not recommended for paver bedding |
Common categories
- Fine gravel/chips (roughly under 3/8 inch): decorative surface topping, some pathway use
- Medium gravel (roughly 3/8 to 3/4 inch): common general-purpose and driveway surface stone
- Larger drainage stone (roughly 3/4 inch and up): French drains, drainage layers, larger decorative stone
- Crusher run / road base (a graded mix of sizes down to fines): compacts into a stable structural base layer
Choosing a size by job
Driveways
A gravel driveway is usually built in layers: larger stone at the bottom where the ground is soft, a compacted dense-graded base such as crusher run in the middle, and a surface layer on top. Clean single-size stone alone tends to roll under tires, so the base layer needs fines to lock together. The Gravel Driveway Calculator handles the layered build-up, and the driveway gravel guide explains typical depths.
Drainage
French drains, footing drains and drainage behind retaining walls want clean, angular stone — #57 is a very common choice — wrapped in filter fabric so soil doesn't migrate into the voids. The French Drain Calculator sizes the trench fill.
Paths, patios and decorative beds
Pea gravel is comfortable underfoot but shifts, so it needs firm edging and a compacted base. For patio and paver bases, use a compacted dense-graded base with a separate bedding layer on top; the paver sand and base guide covers the layers.
Permeable pavers are the exception, because water has to pass through every layer. CMHA's guide specification uses open-graded stone throughout: a bedding layer of about 2 in, typically No. 8 stone, over an open-graded base typically of No. 57 stone 4 in thick, and a subbase typically of No. 2 stone (or a similar size such as No. 3 or No. 4). Layer thicknesses below the bedding are set by the pavement design.
Worked example: gravel for a French drain
A French drain trench 50 ft long, 12 in wide and 18 in deep holds 50 × 1 × 1.5 = 75 ft³. A 4 in perforated pipe along the bottom displaces about π × (2 ÷ 12)² × 50 ≈ 4.4 ft³, leaving about 70.6 ft³ — roughly 2.6 yd³ of stone.
Quarries often sell by weight. At the Crushed Stone Calculator's default of about 1.35 tons per cubic yard for 3/4 in crushed stone, that's around 3.5 tons before any allowance. Confirm the tons-per-yard figure with your supplier, because it changes with rock type and size.
Match the size to the job, not just the look
A driveway surface benefits from a size that compacts and stays relatively stable underfoot and under tires, while a drainage application specifically wants a clean, single-size stone with minimal fines so water can move freely between the particles. Checking your specific supplier's naming and sizing (which varies regionally) against your project's actual functional needs is more reliable than picking by appearance alone.
To turn a size choice into an order, measure the area and depth and run them through the Gravel Calculator, which gives both cubic yards and delivered weight for the material you choose.
Common mistakes
- Using crusher run (with fines) in a French drain — it compacts and stops draining.
- Using clean round stone as a driveway base — it never locks together.
- Ordering by a local name without checking the actual size range.
- Forgetting that depths you measure after compaction need extra loose material.
FAQ
- What size gravel is best for a driveway?
- Most gravel driveways use a compacted dense-graded base such as crusher run, with a surface layer of crushed stone on top. On soft ground, a layer of larger stone such as #3 underneath helps stabilize the base. Clean round stone on its own tends to move under tires.
- What does #57 stone mean?
- It is an ASTM D448 / AASHTO M 43 size number describing crushed stone from 1 in down to the No. 4 sieve (about 3/16 in). It is clean, angular and free-draining, which makes it popular for drainage and permeable-paver bases.
- What gravel is best for drainage?
- Clean, angular, single-size stone with few fines, commonly #57, wrapped in a geotextile filter fabric so surrounding soil doesn't clog the voids.
- Is pea gravel good for a walkway?
- It is comfortable and attractive but shifts underfoot. It works best at a modest depth over a compacted base, with solid edging to keep it in place.
Related Calculators
Related Guides
More From the Blog
Sources
ASTM D448 / AASHTO M 43
Standard sizes of coarse aggregate for highway construction.
CMHA PAV-GSP-016-25, Permeable Interlocking Concrete Pavement
Bedding layer about 2 in (50 mm), typically ASTM No. 8 stone; open-graded base typically No. 57 stone, 4 in (100 mm); subbase typically No. 2 stone or a similar size such as No. 3 or No. 4.
CMHA PAV-GSP-016-25, Permeable Interlocking Concrete Pavement — referenceCMHA PAV-TEC-009-13, Guide Specification for the Construction of Interlocking Concrete Pavement
Bedding sand to ASTM C33 grading; no stone dust or mason sand.
CMHA PAV-TEC-009-13, Guide Specification for the Construction of Interlocking Concrete Pavement — reference