Building and garden · Volumes
Estimate gravel volume and tonnes for an area
For a base course, a path, or drainage: volume comes from the box, mass applies 1,600 kg/m³. That is an order of magnitude; delivered crushed stone can be heavier or lighter.
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How the calculator works
The three dimensions are in meters. Geometric volume is L × W × T, then a margin (10% default) covers compaction and spreading losses. Mass in tonnes divides by 1,000 the product of the increased volume and 1,600 kg/m³. Quarries often sell by the tonne (or the US ton): match that figure to the bulk density on the ticket, not to a universal constant. 1 metric tonne ≈ 1.102 US short tons.
Formula and method
V = L × l × e
In-place volume, before compaction, if all three lengths are in meters.
Vcommande = V × (1 + p / 100)
Margin p for settlement, spreading, and leftover in the truck.
m = Vcommande × 1 600 ; t = m / 1 000
1,600 kg/m³ is a common compacted granular fill, not the density of every aggregate.
The model remains a constant-thickness bed. A V-ditch or a thicker hedgehog under a bearing zone splits into several volumes. 1,600 kg/m³ is an order of magnitude for common aggregates once in place; open rounded drainage stone, dense crushed rock, a 0/80 blend, or recycled material can depart clearly. Quarry sheets talk tonnes and m³ without imposing this figure: ask for “in-place” or “loose” density depending on whether you compact.
Worked example
Drive 10 m × 3 m, 10 cm layer
L = 10 m, W = 3 m, T = 0.10 m, waste = 10%.
- Geometric volume: 10 × 3 × 0.10 = 3.00 m³.
- Increased volume: 3.00 × 1.10 = 3.30 m³.
- Mass: 3.30 × 1,600 = 5,280 kg, or 5.28 t.
3.30 m³, about 5.28 t at 1,600 kg/m³.
Input notes
- Length
- Length of the zone once edges are set (edging, lost form). For a curved path, take centerline length and an average width.
- Width
- Useful width of the layer. Do not include grass shoulders you will not cover.
- Thickness
- Thickness after grading, not the height of the delivered pile. 15 cm = 0.15 m. Beyond 1 m, split the work (base, foundation).
- Waste allowance
- Compaction reduces apparent thickness: ordering in-place volume with no margin often leaves a hole. 10% is a start; energetic compaction may need more material to hit finished thickness.
Assumptions and limits
Assumptions
- Uniform-thickness bed on a rectangle.
- 1,600 kg/m³ to convert volume to mass.
- The margin represents losses and settlement as a lump, not a Proctor test.
Limits
- Gradation (4/6, 20/40, 3/4 inch…) does not enter the math.
- Loose and compacted densities differ: the supplier will decide.
- A very soft subgrade “eats” aggregate beyond the typed margin.
- Geotextile, drains, and edging are not quantified.
How to read the result
Use tonnes to talk to the quarry, and m³ for truck volume. If the sheet says 1,450 or 1,800 kg/m³, scale: real mass ≈ 5.28 × (real density / 1,600). A 10% density gap moves the order by the same amount. For a concrete slab on top, compute concrete separately: the two volumes do not mix.
Common mistakes
Using pre-compaction thickness as finished thickness.
Type the thickness you want after grading. The margin catches part of the settlement, not a lab test.
Using 1,600 kg/m³ for very open decorative gravel or very dense crushed rock.
Delivered density is on the weigh ticket or product sheet. Replace 1,600 with that figure to convert m³ ↔ tonnes.
Ordering in m³ when the yard bills by the ton, without converting.
Both quantities are displayed. Check the tariff unit before rounding the truck.
Related calculations
- Concrete calculatorThe math starts from a rectangular box: volume in m³, then a waste margin. Mass uses 2,400 kg/m³, a typical normal-weight concrete density, not every mix.
- Mulch calculatorA bed is not formwork: mulch settles in a few weeks. The math gives spread volume, a small margin, then the equivalent in 50 L bags.
Frequently asked questions
Where does 1,600 kg/m³ come from?
It is an order of magnitude for common granular fill, not a unique standardized density.
Aggregates vary with rock, gradation, and state (loose, wet, compacted). 1,600 kg/m³ lets the page show coherent tonnes for a common use (base course, path). A supplier may list 1.4 t/m³ or 1.8 t/m³. Jobsite practice and quarry sheets beat this default.
Do I need more material if I compact?
Yes, often. Finished in-place volume is smaller than loose delivered volume.
Compaction packs the grains. For a finished 10 cm, you generally bring more than 10 cm loose. The 10% margin is a lump; a plate compactor over several passes can justify more. A lab compaction test is not reproduced here.
Can I use this for sand or crusher run?
For volume, yes. For tonnes, change the density in your head.
The L × W × T box holds for any constant-thickness bed. Sand, 0/80 all-in, or recycled mix do not have 1,600 kg/m³. Keep the volume, ask for bulk density, then multiply. Garden mulch is another tool: it settles differently and is sold in liters or bags.
What thickness for a driveway?
This calculator does not prescribe thickness. It quantifies the layer you already chose.
Thickness depends on subgrade, traffic, and gradation. A footpath is not a parking pad. Pavement guides treat structure; here you type the thickness already decided and get a volume.
Author and update
Written by Rédaction HexaCalc (editorial team). Content last updated: August 25, 2026. No third-party medical or financial review is claimed.
- Pratiques courantes de calepinage et pertes en travaux (peinture, sols, granulats) — Documents techniques unifiés / fiches fabricants
Slab on top, or mulch beside
For the slab’s concrete volume, use the concrete tool. For a planted bed, switch to mulch: settlement is not that of granular fill.
Calculate slab concreteCategory: Building and garden