21A and 21B are dense-graded crushed-stone base blends — the state-spec versions of crusher run — sold across Virginia and neighboring states. They cost about $20–$45 per ton at the quarry ($30–$65 delivered). 21A carries more fines and compacts tightest, making it the driveway favorite; 21B is slightly coarser and common under asphalt.
What are 21A and 21B gravel?
21A and 21B are grading specification numbers — most famously from the Virginia DOT, with neighboring states using similar systems — for dense-graded aggregate: crushed stone mixed with enough fines (stone dust) that the blend compacts into a near-solid base. If you order "crush and run" in Virginia, there is a good chance the quarry loads material certified to 21A or 21B; if a paving contractor orders "21B," they are buying crusher-run-style stone with a test sheet behind it.
The numbering exists so road and commercial work can be inspected against a defined gradation (the percentage of each particle size the blend must contain). Homeowners get the same stone without needing the paperwork — which is why these products are usually the cheapest compactable base a yard sells. For the wider family of names and grades, see gravel sizes and types.
21A vs 21B: the actual difference
The two blends are siblings, and the difference comes down to how much dust is in the mix:
| 21A | 21B | Plain crusher run | |
|---|---|---|---|
| Fines content | Highest — packs tightest | Moderate | Varies by quarry |
| Drainage | Slow | Slightly better | Slow |
| Typical use | Driveways, pad bases | Under asphalt, road base | General compactable base |
| Price per ton (2026) | $20–$45 | $20–$45 | $20–$35 |
| Spec sheet? | Yes (state graded) | Yes (state graded) | No — generic product |
In practice: if you are building a driveway or shed pad and compacting it yourself, ask for 21A (or crusher run) — the extra fines lock the layer together hardest. If a contractor is paving over the base, they will usually spec 21B. Neither is wrong for a homeowner base; price and availability at your local quarry decide it more than the letter does. Gradations do vary between states, so for anything inspected, get the quarry's current spec sheet rather than trusting the name alone.
21B gravel cost per ton (2026)
State-graded base stone prices in the same band as crusher run, with a small premium at some yards for the certified gradation:
- Picked up at the quarry: $20–$45 per ton (per yard: roughly $28–$63).
- Delivered: $30–$65 per ton effective, once the $50–$150 flat delivery fee is spread over the load.
- Full truckload (10–20 tons): about $300–$850 delivered — the cheapest route per ton.
Delivery is charged per truck, not per ton, so the economics are identical to plain crush and run: bigger loads win. The crush and run cost guide works through those numbers in detail, including spread-and-compacted pricing.
How much 21A or 21B do you need?
Dense-graded base weighs about 1.4 tons per cubic yard, so the standard gravel formula applies: area × depth ÷ 27 × 1.4, plus 10% for compaction and spillage. The quick site rule: 2 tons per 100 square feet at a 4-inch compacted layer.
| Project | Area | Stone needed |
|---|---|---|
| Shed pad | 10 × 10 ft | ~2.3 tons |
| Parking pad | 12 × 20 ft | ~5.5 tons |
| Single-car driveway | 12 × 40 ft | ~9–10 tons |
| Double-car driveway | 20 × 40 ft | ~15–17 tons |
For your exact footprint — and for layered driveway builds where the base, middle and top are different stone — run each layer through the gravel driveway calculator.
Building with 21A/21B: quick tips
- Compact in lifts. Two 2-inch compacted passes beat one 4-inch pass; the fines can only lock up under the compactor plate.
- Use geotextile fabric under the base on soil, so the stone cannot pump into mud over winter.
- Finish as you like. Compacted 21A/21B is a real driving surface; a 2-inch #57 top layer dresses it up and cuts dust.
- Buy by the ton. These blends are weighed at every quarry; a weighbridge ticket removes any argument about bucket counts.
Ready to budget the whole job? Combine this page with gravel cost per ton for delivery economics and cost per cubic yard if your supplier quotes by volume.