How size numbers work
In the US, crushed stone size numbers follow ASTM D448. Each number is a size range: most stone passes the larger sieve and is caught by the smaller one. A lower number usually means larger stone. “No. 4” and “No. 8” at the bottom of a range are sieves (about 4.75 mm and 2.36 mm), not inches.
| Size no. | Nominal range | Typical role |
|---|---|---|
| #1 | 3½ in – 1½ in | Very coarse base and fill |
| #2 | 2½ in – 1½ in | Coarse driveway base |
| #3 | 2 in – 1 in | Coarse base, drainage |
| #4 | 1½ in – ¾ in | Base, drainage |
| #57 | 1 in – No. 4 | Driveway surface, drainage, general purpose |
| #67 | ¾ in – No. 4 | General purpose, concrete aggregate |
| #8 | ⅜ in – No. 8 | Fine surface, bedding |
| #10 | No. 4 – 0 | Screenings / dust |
The “typical role” column describes common uses, not requirements of the standard. Local names vary — some suppliers sell “3/4 in gravel” or “crusher run” instead of a number. Always confirm what you are getting.
Common types at a glance
| Type | Shape | Packs / locks? | Good for | Calculator |
|---|---|---|---|---|
| Pea gravel | Small, rounded | No — it rolls | Patios, paths, play areas, around pavers | Pea gravel |
| Crushed stone (#57, #2 …) | Angular | Yes | Driveways, pads, bases, drainage | Stone |
| Crusher run / road base | Angular with fines | Yes, when compacted | Compacted base layers | Stone or driveway |
| River rock | Smooth, rounded, larger | No | Dry creek beds, borders, downspouts | River rock |
| Landscape / decorative rock | Varies | Varies | Beds and borders | Rock |
Choosing by job
- Something you'll drive on
- Angular crushed stone, usually in layers — coarse underneath, finer on top. See the driveway guide.
- Something you'll walk on
- Smaller stone is more comfortable. Rounded pea gravel is pleasant but moves underfoot; edging helps keep it in place.
- Drainage
- Clean stone without fines (for example #57) leaves space for water. Stone with fines (crusher run) compacts but drains less freely.
- Looks
- River rock and decorative rock are chosen for colour and texture. Larger pieces need a deeper layer to cover the ground.
Does the type change the weight?
Yes, somewhat: rock type, size, shape, fines and moisture all change weight per yard. We give a published gravel range and explain the variation in how much a yard of gravel weighs.