How Much Gravel Do I Need?
The basic gravel calculation is straightforward: multiply the length by the width by the depth to get the volume in cubic metres. For driveways and frequently trafficked areas, a depth of at least 50 millimetres is recommended over a compacted sub-base. Decorative borders and garden paths can use a shallower 25 to 30 millimetre layer. Once you have the volume, multiply by the density of your chosen aggregate to convert to weight in tonnes. Most decorative gravels have a bulk density of approximately 1.5 to 1.8 tonnes per cubic metre.
Gravel is typically sold in bulk bags of 850 to 900 kilograms or by the tonne for larger quantities. Small quantities are available in 20-kilogram bags from DIY stores, though this is far more expensive per tonne. For driveways, always specify angular or self-binding gravel rather than rounded pebbles, as angular stones lock together under traffic and are less likely to spread or scatter.
Types of Gravel and Aggregate
Pea gravel is a popular choice for garden paths and borders thanks to its rounded, smooth appearance. Cotswold stone and golden gravel suit traditional and rural properties. Slate chippings offer a contemporary look in blue, plum or grey tones. For driveways, 20-millimetre angular gravel or MOT Type 1 sub-base provide the necessary stability and drainage. Resin-bound gravel creates a smooth, permeable surface that meets sustainable drainage requirements without the loose stones.
When creating a gravel driveway, you must consider drainage regulations. Since 2008, front gardens in England with an area over five square metres that are being paved with impermeable materials require planning permission. Using permeable gravel or resin-bound surfaces avoids this requirement and helps manage surface water runoff.
Preparing the Ground for Gravel
Proper ground preparation ensures your gravel stays in place and drains correctly. Remove existing turf or vegetation, excavate to the required depth including sub-base, compact the soil and lay a weed membrane before adding the aggregate. Edge restraints such as timber boards, metal edging or brick borders prevent the gravel from spreading into lawns and flower beds. For driveways, a compacted Type 1 sub-base of at least 100 millimetres provides a stable foundation.
For more outdoor project estimates, try our decking calculator or fence calculator. For planning and drainage rules, visit GOV.UK.
This calculator provides estimates for guidance only. Results are based on the figures you enter and typical UK averages. This is not professional, financial, medical or legal advice. Always consult a qualified professional for specific guidance.