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Gravel Calculator

Estimate gravel volume, weight and cost for paths, beds, bases and drainage layers.

Your estimate

Enter measurements, then calculate.

Planning estimate only. Confirm packaging, coverage, site conditions, and local building requirements before purchasing.

How to measure

Measure the length and width of the area to be covered after edging or borders are planned.
Choose the finished gravel depth based on use: decorative beds are thinner than driveways or base layers.
For curved paths, divide the shape into short rectangles or measure an average width along the path.
Confirm whether the supplier sells by tonne, short ton, bag or cubic volume before using the cost result.

Input guide

Depth is entered in centimetres or inches because gravel layers are usually shallow compared with their length and width.
Density depends on stone type, moisture and compaction. A typical loose gravel estimate often uses around 1.6 tonnes per cubic metre.
Waste covers settling, spreading loss and small variations in ground level. Base layers may need more allowance after compaction.
Price should match the purchase unit shown by the result: tonne for metric or short ton for imperial.

Formula

Weight = length × width × depth × (1 + waste) × density

The calculator first finds the gravel layer volume, then multiplies by density to estimate weight.

Waste is applied to the volume before weight conversion so the result reflects extra material for leveling and compaction.

Density is user-entered because pea gravel, crushed rock and damp aggregate can weigh differently.

Worked example: Garden path gravel

A 10 m by 1.2 m path covers 12 m².
At 5 cm depth, the raw volume is 0.60 m³.
With 10% waste, the adjusted volume is 0.66 m³.
At 1.6 t/m³ density, the estimate is 1.06 tonnes.

If gravel costs 48 USD per tonne, the material estimate is about 50.88 USD before edging, fabric or delivery.

Buying advice

Ask the supplier whether their price is for loose tonne, compacted tonne, bulk bag or cubic yard.
For driveways and bases, confirm compaction requirements; compacted layers may need staged placement rather than one loose layer.
Use landscape fabric only where appropriate; it can help with weed control but may not suit every drainage layer.

Common mistakes

Using decorative depth for a driveway or structural base
Forgetting that gravel settles after spreading and compaction
Using a generic density for a very different stone product
Pricing by bag while the result is by tonne
Ignoring delivery minimums for bulk aggregate

Use compacted depth for the finished layer

A gravel layer settles when spread, watered, trafficked, or mechanically compacted. If the project specifies a finished compacted depth, the loose delivered volume may need to be higher. The difference depends on aggregate grading, moisture, angularity, and the compaction method.

Measure the prepared base after unsuitable soil is removed. Deep low spots should be corrected deliberately rather than hidden inside one average depth, especially for driveways and drainage work.

Match the supplier’s material and selling unit

Ask for the bulk density or conversion factor for the exact aggregate, not a generic gravel value.
Confirm whether the supplier sells by tonne, short ton, cubic metre, cubic yard, bag, or truck load.
Check whether the quoted weight is dry, damp, or based on a standard conversion.
Include delivery minimums and vehicle access when comparing two prices.
Order the specified grading because decorative stone, drainage aggregate, and compactable base are not interchangeable.

Drainage and base design still need judgment

This result estimates volume, mass from an entered density, and cost. It does not select aggregate size, geotextile, edging, drainage falls, excavation depth, sub-base layers, or compaction equipment.

For retaining structures, load-bearing bases, roads, septic work, or drainage near buildings, use the project specification and local professional guidance. The wrong material or slope can fail even when the delivered tonnage matches the estimate.

Frequently asked questions

What gravel depth should I use?

Decorative beds may use 3–5 cm, paths often use 5–8 cm and driveways or bases need a design-specific layered depth.

Why does density matter?

The same volume of different stone can have different weight, and many suppliers price gravel by weight.

Does this include compaction?

It includes a waste allowance but does not model engineered compaction. Increase allowance or ask the supplier for base-layer guidance.

Can I use this for mulch?

Not directly. Mulch is usually ordered by volume and has a much lower density than gravel.

Should I round up the result?

Yes. Suppliers often sell in half-tonne, full-tonne or bag increments, so round to their ordering unit.