How much gravel for 20 m² at 10 cm deep?
20 square metres at 10 cm deep needs about 3.66 tonnes of gravel, or 2.21 cubic metres loose, allowing for settling and 5% waste. In bulk bags of about 850 kg, that is 5 bags.
How to work it out
- Area: 20 m²
- 20 m² × 0.1 m = 2 m³
- 2 m³ compacted × 1.05 = 2.1 m³ loose × 1.66 t/m³ = 3.49 t
- + 5% waste = 3.66 t
- Effective rate: ≈ 1.83 t per m³ compacted
- Bulk: 3.66 t rounded up to the next 0.5 t = 4 t
Twenty square metres at 10 cm is a typical parking space, shed base or a small courtyard. In metric the maths is tidy: every square metre at 10 cm deep is 0.1 m³, so 20 m² is 2 m³ in place. This example uses 20 mm crushed stone, the metric cousin of US #57.
Adjust for your project
More options: Compaction · Waste · Price …
- Loose volume (as delivered)
- 2.21 m³ (2,205 L)
- Bulk order (rounded up)
- 4 tonnes
- Quarries and landscape yards sell by the ton or half ton and deliver in full loads — ask about minimum orders and short-load fees.
Gravel at 10 cm deep by area
| Area | Gravel to order | Loose volume (as delivered) |
|---|---|---|
| 10 m² | 1.83 tonnes | 1.1 m³ |
| 15 m² | 2.75 tonnes | 1.65 m³ |
| 20 m² | 3.66 tonnes | 2.21 m³ |
| 25 m² | 4.58 tonnes | 2.76 m³ |
| 30 m² | 5.49 tonnes | 3.31 m³ |
| 40 m² | 7.33 tonnes | 4.41 m³ |
What to know about 20 m² of gravel at 10 cm
Aggregates in metric markets are usually sold by the tonne, either loose from a tipper lorry or in bulk bags of roughly 800–900 kg. The calculator uses a typical 1.66 t/m³ for clean crushed stone as it comes off the lorry, and adds about 5% because even clean stone settles a little when you tamp it. Ask your merchant for the density of their product if they sell by volume.
Bulk bags are delivered by a lorry with a crane arm, which has to park within reach of where the bag goes. Ask the merchant how far their crane reaches and measure before ordering, or you may end up barrowing several tonnes up a side passage.
For a parking space, 10 cm of stone on its own will rut. Most driveway builds use 15 cm or more of compacted sub-base (Type 1 in the UK) under a decorative top layer — see the variants below. For a shed base, the imperial version of this job is how much gravel for a 12×16 shed base, and the same foot-past-the-walls rule for sizing the pad applies.
Different size? Use the full Gravel Calculator.
What you’ll need
- Bow rake / landscape rakeBudget price
Steel tines for spreading gravel and soil and leveling it flat. The flat back of a bow rake doubles as a leveling tool.
See options on Amazon (opens in a new tab) - Wheelbarrow (6 cu ft class)Mid-range price
Most home wheelbarrows hold 4–6 cubic feet — so a cubic yard of mulch is five or six trips. Two wheels are steadier on soft ground.
See options on Amazon (opens in a new tab) - Woven geotextile (driveway fabric)Mid-range price
Goes under the base of a gravel driveway or path to keep stone from sinking into soft soil.
See options on Amazon (opens in a new tab)
As an Amazon Associate we earn from qualifying purchases. Links to products are affiliate links — they cost you nothing extra and help keep these calculators free.
Frequently asked questions
How much gravel for 20 m² at 15 cm deep?
About 5.49 tonnes of clean stone with settling and 5% waste. Fifteen centimetres is the usual minimum for a sub-base that cars will drive on.
How much compacted sub-base for 20 m² at 15 cm?
About 7.01 tonnes of dense-graded sub-base (crusher run; Type 1 in the UK), because it packs down about a fifth when you compact it. That is 3.94 cubic metres loose.
How much gravel for 20 m² at 5 cm deep?
About 1.83 tonnes with settling and 5% waste. Five centimetres is a decorative top layer for a path or border, not a base.
Other common sizes
- How much gravel for a 10×12 shed base — 3.2 tons
- How much gravel for a 12×16 shed base — 6.13 tons
- How much gravel for a 10×10 area — 1.91 tons
- How much pea gravel for a 3×30 ft garden path — 1.26 tons
Sources
- FHWA — Gravel Roads Construction and Maintenance Guide (2015) (opens in a new tab) — Why crushed, fractured stone holds under load better than rounded stone
- Wisconsin DOT research report 0092-22-05 — Weight-Volume Relationships and Conversion Factors for Soils and Aggregates (2024) (opens in a new tab) — WisDOT conversion factors for compacted dense-graded base: 1.75–2.1 tons per cubic yard (Table 1.2); measured 1.78–1.98 (Table E2)
- FHWA-HRT-15-034 — Strength Characterization of Open-Graded Aggregates for Structural Backfills (opens in a new tab) — No. 57 stone: minimum (loosest) 95.4 pcf, maximum (vibrated) 108.7 pcf dry unit weight (Table 7)
- Gravel Monkey — How many tons of gravel in a dump truck? (opens in a new tab) — Typical payloads: single-axle about 6–10 tons, tandem 12–16, tri-axle 18–25; gravel hits the weight limit before the bed is full.