Limestone sizes and uses
Limestone is sold by AASHTO size grade, the same numbering system used for other crushed stone. The grade tells you the size range of the rock; the density is essentially the same across all sizes (~2,650–2,750 lb/yd³).
- 2A modified / CA6 limestone — dense-grade, with fines, for driveway bases.
- 2B limestone — 1½" clean stone for deep bases or rough drainage.
- #4 limestone — 1.5" – 2.5", deep base or erosion control.
- #57 limestone — ¾", the most common driveway / drainage stone.
- #8 limestone — ⅜"–½", paver bedding.
- Screenings / 1 fines — dust + small chips, for setting joints in flagstone.
Limestone gravel sizes and weight per yard
The same list, sorted from finest to coarsest, with the weight per cubic yard so you can convert straight to a tonnage order:
| Grade | Size | Weight/yd³ | Typical use |
|---|---|---|---|
| Screenings / 1 fines | dust – ¼" | 2,700 lb | Flagstone joints, bedding |
| #8 | ⅜" – ½" | 2,700 lb | Paver bedding |
| #57 | ¾" (¼" – 1½") | 2,750 lb | Driveways, drainage |
| 2B | 1½" clean | 2,700 lb | Deep base, rough drainage |
| #4 | 1.5" – 2.5" | 2,650 lb | Deep base, erosion fill |
| CA6 / 2A modified | 1" down to dust | 2,650 lb | Compacted driveway base |
These grades follow the AASHTO/ASTM size numbering set by sieve analysis under ASTM C136/C136M, so "#57 limestone" means the same size envelope wherever it's quarried.
Recommended depth & material
| Use | Depth | Material | Notes |
|---|---|---|---|
| Driveway base (compacted) | 4" | CA6 / 2A modified limestone | Has fines; compacts hard. |
| Driveway top course | 2" | #57 limestone | Drains; doesn't pack. |
| Paver patio base | 4" | CA6 limestone | Topped with 1" sand. |
| Deep base / erosion fill | 6"+ | #4 or 2B limestone | For trucks or soft soil. |
| Paver bedding sand alternative | 1" | #8 limestone screenings | Works under stone pavers. |
Ordering limestone
Sold by the ton at every U.S. limestone quarry. Standard rectangular math: length × width × depth. Use a 10–15% buffer depending on whether the variant includes fines (compacts more = higher buffer) or is washed clean (lower buffer).
- Pick the size grade. Match the AASHTO number to your use case.
- Length × width × depth. Standard volume math; calculator does the unit conversion.
- Set the buffer. 10% for clean #57 / #8; 15% for CA6 / 2A modified with fines.
- Order in tons. Limestone is always quoted by the ton in the U.S.
Worked example — 600 sq ft path with limestone screenings
A 60 × 10 ft pathway needing 1 inch of #8 limestone screenings as bedding: volume = 600 × (1/12) ÷ 27 = 1.85 yd³. At 2,700 lb/yd³, that's 2.5 tons. With a 10% buffer: 2.0 yd³ / 2.75 tons. At $42/ton delivered: $116.