How this stone dust calculator works
Stone dust is sold over a scale like any aggregate — volume times density — and because a setting bed is thin, small depth changes swing the tonnage:
tons = yd³ × 1.35 × (1 + waste%) → rounded up to ¼ ton
At the defaults — a 20 × 10 ft patio, a 1 in screeded bed, 10% allowance — the order is 1 ton, about $45 bulk or 37 bags; the full chain is in the load math section below.
What is stone dust, and what it’s for
Stone dust is the crusher’s finest output — powder to about 3/16 in — sold under a pile of regional names, all the same idea: fines that pack tight and hold shape. Where it belongs, and where it doesn’t:
- Screenings / quarry dust / grit: the loose product straight from the screen — 1.35 t/yd³, the calculator’s default.
- Flagstone & stepper bedding: its best job — a stiff, packable 1 in bed that holds irregular stone dead flat.
- Wall block leveling: a screeded base course under the first row of a retaining or garden wall.
- Path surfacing: compacts into a hard, walkable trail top at 2–3 in — think crushed-limestone paths and rail-trails.
- Not under interlocking pavers: ICPI specs concrete sand there, because dust holds water and won’t let pavers seat and drain. Use the paver base calculator for that.
How deep should a stone dust bed be?
Thin and screeded is the rule — stone dust is a leveling layer, not a structural one, so more depth just means more to compact and more to buy:
- Flagstone / stepper bed: 1 in screeded flat over a compacted base.
- Wall leveling course: 1 in under the first block row, dead level.
- Path surface: 2–3 in compacted for a walkable trail top.
- Joint filling: swept into flagstone joints after setting — figured separately from the bed.
- Never the whole base: under any load the structure is the compacted crushed stone below; dust just beds the surface.
How much does a ton of stone dust cover?
Table 1 is coverage per ton by depth; Table 2 is where screenings belong and where they don’t.
| Depth | 1 ton covers |
|---|---|
| 1″ | 240 ft² |
| 2″ | 120 ft² |
| 3″ | 80 ft² |
| 4″ | 60 ft² |
| Use | Bed / call |
|---|---|
| Flagstone / steppers | 1″ screeded bed ✓ |
| Wall block base | 1″ leveling ✓ |
| Path surface | 2–3″ compacted ✓ |
| Interlocking pavers | Use concrete sand ✗ |
How to measure for stone dust
- Measure the bed length and width; total odd shapes with the square footage calculator.
- Set the depth thin — 1 in for a bedding course, 2–3 in only for a compacted path surface.
- Pick loose or compacted density — loose for a delivered pile, compacted if you’re estimating the packed volume in place.
- Leave the allowance at 10% — screeding wastes a little, and you’ll want extra to sweep into joints.
- Enter the per-ton price, or the bag price for a small bed — stone dust is one of the cheapest things the quarry sells.
Worked example: stone dust for a 20 × 10 flagstone patio
The default, worked line by line — a 1 in screeded bed over 200 ft², 1.35 t/yd³, 10% allowance, $45 a ton:
volume = 200 × (1 ÷ 12) = 16.7 ft³ = 0.62 yd³
weight = 0.62 × 1.35 = 0.83 tons exact
allowance = 0.83 × 1.10 = 0.92 → order 1 ton
cost = 1 × $45 = $45 · bags: (16.7 × 1.1) ÷ 0.5 = 37 · covers 240 ft² at 1″
A single ton beds most patios in one delivery, which is the nice thing about a thin material: 240 ft² of flagstone off one scoop. The trap is going deep “to be safe” — a 3 in dust bed under flagstone stays spongy and heaves, where a screeded inch over a compacted base holds flat for years.
What this stone dust estimate doesn’t include
Screenings are cheap — often the cheapest line on the quarry ticket — but the bed is the small part of a flagstone job. These items usually add up to more than the dust itself, so keep every one of them on the estimate:
- The compacted base. Flagstone and walls bed on stone dust but stand on a crushed-stone base below — a separate order.
- The flagstone or block. The surface itself, priced by the piece or the pallet.
- Joint filler. Extra dust or polymeric sand swept into the joints after setting.
- Delivery. A flat per-load fee — real money on a cheap material.
- Compaction. A plate compactor for path surfaces and the base.
- Edging. Restraint to hold the surface and the stone.
Stone dust FAQ
How much stone dust do I need?
A 1 in setting bed over the default 20 × 10 ft patio is 16.7 ft³ — 0.62 yd³, or 0.83 tons; with 10% allowance you order 1 ton (about $45 bulk, or 37 half-cubic-foot bags). The calculator rescales for any area and depth.
What is stone dust?
The finest product of the crusher — particles from powder up to about 3/16 in, sold as screenings, quarry dust, decomposed fines or grit. It packs nearly watertight underfoot, which is what makes it a bedding and path material rather than a drainage one.
Stone dust or sand under pavers?
Concrete sand for interlocking concrete pavers — the ICPI standard — because it drains and lets the pavers seat. Stone dust shines under dry-laid flagstone, steppers and wall block, where its packed stiffness holds irregular stone dead flat.
How much stone dust for a 100 square foot patio?
At a 1 in screeded bed, 100 ft² takes about 0.5 tons of screenings with the 10% allowance — 9.2 ft³, or roughly 20 half-cubic-foot bags. Double the number for a 2 in bed. Under flagstone that will bear foot traffic, a 1 in bed screeded dead flat is the sweet spot.
How many tons of stone dust are in a cubic yard?
About 1.35 tons loose, rising toward 1.4 once compacted in place — the fines leave very little void space. Both figures are in the material picker.
How much does a ton of stone dust cover?
240 ft² at a 1 in screed — 120 ft² at 2 in, 60 at 4 in. A ton goes a long way in beds; it disappears fast when used as a path surface at 3–4 in.
How much does stone dust cost?
Usually $30–60 per ton bulk in 2026 — often the cheapest thing at the quarry — and about $5 per half-cubic-foot bag. The default bed is $45 bulk versus roughly $185 bagged, the usual bulk-wins math past a ton.
Sources and standards
Stone dust has no single ASTM product number the way #57 stone does; the guidance below is what dry-laid stone practice and the paver industry actually say about where fines belong and where they don’t:
- ICPI guidance: concrete sand — not stone dust — as the bedding under interlocking concrete pavers.
- Dry-laid stone practice: the 1 in screeded screenings bed for flagstone and steppers over a compacted base.
- Standard estimating density: 1.35 t/yd³ loose, ~1.4 compacted, matching the site-wide aggregate set.
- The scale ticket: fines hold moisture and weigh heavy wet — the weighed load governs the invoice.
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