Gravel Calculator

How much gravel do I need?

The amount of gravel you need depends on three main measurements: the length of the area, its width and the depth of the gravel layer. AmountHub's gravel calculator uses these measurements to estimate the total volume and approximate weight of gravel required for your project.

Enter the dimensions of your driveway, garden path, patio or landscaping area and choose either metric or imperial units. The calculator converts the measurements automatically and estimates the result in cubic metres and tonnes, or cubic yards and US tons.

For smaller projects, the result is also displayed in kilograms or pounds so that you do not have to convert a small fraction of a tonne yourself.

How the gravel calculator works

Gravel quantity is calculated by first finding the volume of the area. For a rectangular area, the basic calculation is:

Length × Width × Depth = Gravel Volume

The volume is then multiplied by an estimated density for the selected gravel type. Different materials have different densities, so pea gravel, crushed stone and river rock may produce slightly different weight estimates even when the volume is the same.

By default, the calculator adds 10% extra material to help account for uneven ground, settling, compaction and small losses during delivery or installation.

Worked example

Suppose you want to build a narrow gravel path through a garden that is 8 m long, 1.2 m wide and finished with a 5 cm gravel layer.

In practice, you would then compare that estimate with the supplier's available bag sizes or bulk-delivery minimums. If the path has dips, soft edges or a base layer that still needs filling, measuring those areas separately can give a more reliable order quantity.

This is why AmountHub shows both volume and estimated weight: volume describes the space you need to fill, while weight is usually closer to how bulk gravel is sold.

How deep should gravel be?

The correct gravel depth depends on how the area will be used. Decorative gravel normally requires a much shallower layer than a driveway or structural base.

These figures are general planning estimates. Projects that carry vehicles or require drainage and structural support may need additional compacted base layers underneath the visible gravel.

How much does a cubic metre of gravel weigh?

Gravel does not have one exact weight because density changes depending on stone size, material, moisture and how tightly it is compacted.

As a general estimate, many common gravel types weigh around 1.6 to 1.8 tonnes per cubic metre.

• General gravel: approximately 1.70 tonnes per m³
• Pea gravel: approximately 1.60 tonnes per m³
• Crushed stone: approximately 1.75 tonnes per m³
• River rock: approximately 1.65 tonnes per m³

If your supplier provides a specific density for the product you plan to purchase, their figure should be considered more accurate for that particular material.

When the supplier gives you a density

Select “Use supplier density” and enter the quoted bulk density for the exact stone. For the 8 m × 1.2 m path above, 0.528 m³ including the 10% allowance weighs about 0.90 tonnes at the preset 1.70 t/m³. At a supplier value of 1.80 t/m³ it weighs about 0.95 tonnes. The volume has not changed; only the estimated weight and bag or bulk order have. In Imperial mode the field accepts lb/yd³.

Should I order extra gravel?

Ordering slightly more gravel than the mathematical minimum can be useful. Ground is rarely perfectly level, measurements may not be exact, and gravel can settle or compact after installation.

A 10% allowance is a simple general estimate, which is why it is enabled by default in the calculator.

Project guides

If you are still planning the job, these guides explain the steps around the calculation itself. They are useful when your area is irregular, when you are unsure how much extra material to buy, or when your supplier uses a different unit system.

For details on how AmountHub handles formulas, assumptions, rounding and product-specific figures, see the calculator methodology and quality standards.

Measure an L-shaped project

Use the first length and width for the main path, then add a separate section for each wider or angled portion you can measure as a rectangle. For example, an 8 m × 1.2 m path plus a 2 m × 1.5 m landing has a combined area of 12.6 m². At 5 cm deep, that is 0.63 m³ before allowance. With 10% extra and general gravel at 1.70 t/m³, the estimate is about 1.18 tonnes. Overlapping sections should be measured only once.

Before you order gravel

A calculator is most useful when the measurements and product information are realistic. Before ordering, check the finished dimensions one more time, confirm the planned depth, and ask the supplier whether the gravel density or coverage differs from the general estimate used here.

• Measure irregular areas in smaller sections rather than forcing everything into one rectangle.
• Use the finished gravel depth, not the depth of a loose pile.
• Check whether a compacted base layer is required underneath the decorative or surface gravel.
• Confirm whether your supplier sells by tonne, cubic metre, bulk bag or smaller bag.
• Keep delivery access and any minimum-order quantity in mind when comparing the calculated amount with the final purchase.

Frequently asked questions