Gravel, Sand & Aggregate Calculator
Whether you are ordering pea gravel for a garden path, crushed stone for a driveway sub-base, or sharp sand for a mortar bed, getting the quantity right saves a second delivery charge and avoids a surplus you have to dispose of.
This calculator converts area and depth into order weight (tonnes or short tons) and order volume (m³ or yd³), accounting separately for compaction — how much the material settles into place — and handling waste. Most online calculators merge these into a single overage percentage, which produces a systematically wrong answer for highly-compacted materials like MOT Type 1 sub-base. Siteometry keeps them separate.
Add as many zones as your project needs, choose a material preset or enter your own bulk density, and the results rail updates in real time. Switch to Coverage mode to work backwards from a known quantity.
How to use the gravel calculator
Start by choosing metric or imperial units at the top. The calculator remembers your preference in your browser.
Open the Material & assumptions card to pick a material preset. The bulk density and compaction percentage fill in automatically, but you can override either value for your specific product.
Add a zone for each distinct area: choose its shape (rectangle, circle, triangle, or direct area entry), enter the dimensions and depth, and the zone shows a per-area breakdown. The Results panel on the right accumulates every zone into a single order weight and volume.
To estimate coverage from a known quantity — for example, if a supplier offers a 10-tonne bulk bag — switch to Coverage mode, enter the quantity and depth, and the panel shows how many square metres or square feet it covers.
How to calculate gravel quantities in 5 steps
- Choose unitsSelect metric (m, mm, tonnes, m³) or imperial (ft, in, short tons, yd³) at the top of the page.
- Pick a materialOpen Material & assumptions and choose from eight presets, or select Custom and enter the bulk density for your specific product.
- Add zonesAdd one zone per distinct area. Choose a shape (rectangle, circle, triangle or direct area), then enter the dimensions and depth.
- Set compaction and wasteAdjust the compaction and waste percentages in the assumptions card. The defaults match each material preset but can be overridden.
- Read the resultsThe results panel shows order weight (rounded up to your supplier's minimum), loose volume, bag count, approximate truck loads and optional cost.
How the formula works
The calculation runs in three stages for each zone.
First, the loose delivered volume is simply area multiplied by depth. This is the volume of material as it arrives from the supplier in a loose, uncompacted state.
Second, the compacted volume accounts for settlement: looseVolume ÷ (1 + compactionFraction). A pea-gravel path with 8% compaction means the compacted depth is about 7% less than the loose depth.
Third, the order volume adds handling waste: compactedVolume × (1 + wasteFraction). Order weight follows by multiplying order volume by the material's bulk density.
Material bulk density reference
Bulk density values vary with particle size, shape, moisture content and compaction state. The figures below are representative dry loose bulk densities — the mass of material per cubic metre as delivered, without any compaction applied. Wet or compacted material is heavier.
Use these as starting points and enter your supplier's stated density if you have it.
| Material | Bulk density (kg/m³) | Typical compaction |
|---|---|---|
| Pea gravel | 1680 | 8% |
| Crushed stone (#57) | 1600 | 12% |
| River gravel | 1550 | 8% |
| MOT Type 1 / sub-base | 2100 | 20% |
| Sharp sand | 1600 | 12% |
| Builder's sand | 1450 | 12% |
| Play sand | 1500 | 8% |
| Topsoil | 1200 | 15% |
Frequently asked questions
How many tonnes of gravel do I need?
Enter the area dimensions and depth for each zone, choose your material (which sets the bulk density), and the calculator works out the order weight in tonnes. It compounds a compaction factor and a waste factor separately — both are shown in the assumptions card — and rounds the result up to your supplier's minimum order increment.
What is a compaction factor and why does it matter?
Compaction is how much a material settles after it is laid and compressed into place. Pea gravel settles about 8%, meaning a 100 mm loose depth compacts to roughly 93 mm. MOT Type 1 sub-base compacts around 20%, so a 100 mm finish depth needs 125 mm of loose material. Without separating compaction from waste, the order quantity is systematically wrong for high-compaction materials.
How many cubic yards of gravel are in a tonne?
It depends on the material's bulk density. For pea gravel at 1680 kg/m³: 1 tonne ÷ 1680 kg/m³ ≈ 0.595 m³ ≈ 0.778 yd³. For MOT Type 1 at 2100 kg/m³: 1 tonne ÷ 2100 ≈ 0.476 m³ ≈ 0.623 yd³. Switch the calculator to imperial to get yd³ output directly.
What is the difference between pea gravel and crushed stone?
Pea gravel is naturally rounded, about 6–9 mm diameter, with a bulk density around 1680 kg/m³ and low compaction (8%). Crushed stone (#57 grade) is angular, which locks together under compaction — its density is around 1600 kg/m³ but compaction is higher at 12%. For driveways and structural sub-bases, angular crushed stone or MOT Type 1 is usually specified; for paths and decorative use, pea or river gravel is common.
How do I calculate gravel for a driveway?
Measure the driveway length and width. Typical driveway gravel depth is 75–100 mm for a decorative surface, or 150–200 mm for a structural sub-base (two layers). Add a zone per section, set the material to MOT Type 1 for sub-base or crushed stone for surface, and the calculator gives the order weight. A 10% waste allowance is set by default for driveways.
What does loose vs compacted volume mean?
Loose (delivered) volume is the quantity you order and receive — gravel in a tipper truck occupies more space than when it is laid and compacted. Compacted volume is the in-place volume after rolling or tamping. The results rail shows both so you know what to order and what you will end up with on site.
What is Coverage mode?
Coverage mode works backwards from a known quantity. If a supplier offers a 5-tonne bulk delivery at a fixed price, enter 5 tonnes, the material and the target depth, and the calculator shows how many square metres that covers — accounting for compaction and waste in reverse.
Does the calculator work in metric and imperial?
Both. Switch units at the top and every dimension, weight and volume converts: depths in mm or inches, areas in m² or ft², order weight in tonnes or short tons, volume in m³ or yd³.
Is the calculator private?
Yes. Every calculation runs entirely in your browser. Nothing you enter is sent to any server, and your project is saved only in your own browser's local storage.