Gravel Calculator — Tonnes & Cost

Gravel quantity is calculated by multiplying area × depth to get volume, then converting to tonnes using the bulk density. Most decorative gravel has a bulk density of 1.5–1.8 t/m³. A typical driveway uses a 40–50 mm depth of gravel over a compacted sub-base. Paths and borders need 25–40 mm depth.

This calculator shows results in cubic metres, tonnes and bulk bags (a standard bulk bag contains approximately 0.5 m³ or 0.8–0.9 tonnes). For driveways, a geo-textile membrane under the gravel prevents weed growth and stops gravel mixing with the sub-base. Gravel grids (honeycomb panels) stabilise the surface for vehicle use.

Enter the area dimensions and desired depth. The calculator shows volume, weight in tonnes, number of bulk bags and estimated cost (delivered gravel in the UK typically costs £50–£80 per tonne for standard aggregates, or £80–£150 per tonne for premium decorative gravel).

How much gravel do you need? Volume = length × width × depth. For typical decorative paths: 50mm depth. For driveways supporting cars: 75-100mm depth (over compacted Type 1 sub-base). Convert to weight: gravel density ~1.5 tonnes/m³. Sample drive 10m × 3m × 0.075m = 2.25 m³ × 1.5 = 3.4 tonnes. Bulk bag (UK standard) holds 0.5-0.6 m³ (750-900kg). Sample drive needs 4 bulk bags. Loose tipper truck delivery (5+ tonnes): much cheaper per tonne but needs space and access.

UK gravel types and prices 2026. 10mm pea gravel (paths, drainage): £45-£75/bulk bag. 20mm Cotswold buff (driveways, decorative): £60-£100. Slate chippings: £80-£140 (Welsh slate premium). Resin-bound gravel (mixed with resin, installed by contractor): £80-£150/m² laid (premium driveway finish). Limestone chippings: £55-£90. Granite chippings: £70-£110. Always check origin — Cotswold gravel from Welsh quarries is darker than 'genuine' Cotswold limestone. Local quarries (within 20 miles) significantly cheaper due to haulage.

Sub-base — the foundation that lasts. Driveway gravel cannot just be tipped onto soil — it sinks, weeds break through, ruts form. Proper buildup (bottom-up): excavated soil 250-300mm depth; weed membrane (Geofabric); 150mm compacted Type 1 MOT sub-base (£40-£60/tonne); optional gravel grid (Nidagravel, X-Grid) £15-£30/m²; 50-75mm decorative gravel topping. Grids contain the gravel and stop it migrating to grass — without grids, expect to top up annually. Edging (timber, stone, plastic) £8-£20/m linear stops escape.

Planning permission and council rules. New driveways over 5 m² in front gardens (England since 2008): require either permeable surface OR planning permission. Permeable gravel (loose, not bound) qualifies for permitted development. Block paving requires permeable joints/sub-base. Resin-bound porous gravel qualifies. Bonded resin (impermeable): requires planning. Rules introduced to manage surface water runoff and flooding. Most gravel driveways DO meet permitted development — check with your council before laying.

Maintenance and longevity. Annual: rake to redistribute even coverage. Top up every 1-3 years if no grid (½ bulk bag for average drive). Weeding: weed membrane prevents ground weeds; air-blown seeds will sprout — pull manually or treat with glyphosate (banned in many cases — check). Loose gravel scattered on road: legal obligation to keep within boundary; shovels back. Gravel + cars: heaviest cars rut without grid; SUVs/4x4 manageable on 75mm+ depth. Snow: gravel + snow = challenging to shovel; salt corrodes some gravel types.