How Much Gravel Do You Need for a Driveway?

Length times width gives the plan area. Irregular drives should be split into rectangles or triangles and added together. Measure the usable driving surface, not the whole plot boundary, unless you are also graveling verges, parking bays, or a turning circle.

If the drive tapers, use average width. A 40 ft drive that is 10 ft at the road and 14 ft at the house is roughly 12 ft average width for planning: 40 × 12 = 480 sq ft. In metric, a 12 m drive averaging 3.5 m wide is 42 m². Write the figure down before you touch depth.

Curves are still area problems: sketch, split into tape-measure rectangles, and add. Satellite guesses without a ground check order for the wrong driveway.

A common planning depth for a light residential drive is 4–6 inches (100–150 mm) of compacted angular stone, sometimes over a geotextile. Pedestrian paths are often thinner. Going from 4 inches to 6 inches is a 50% increase in volume for the same area — that is not a rounding error, it is half a truck.

Worked example (imperial): 480 sq ft at 4 inches deep. Convert depth to feet: 4/12 = 0.333 ft. Volume ≈ 480 × 0.333 ≈ 160 cubic feet ≈ 5.9 cubic yards. At 6 inches (0.5 ft): 480 × 0.5 = 240 cubic feet ≈ 8.9 cubic yards. Same footprint; very different order.

Worked example (metric): 42 m² at 100 mm (0.10 m) is 4.2 m³. At 150 mm it is 6.3 m³. Run the same numbers in the Gravel Calculator so the unit labels match what your merchant sells. Do not mix inches of depth with a metre length mid-calculation.

Suppliers deliver loose material. You compact it. A finished compacted depth is not the same as the loose depth in the truck. Ordering a little extra — often in the 5–10% range for DIY drives — covers compaction and minor low spots in the subgrade. Confirm whether your supplier’s coverage chart already assumes compacted depth.

Soft clay, old fill, or a drive that already ruts will need more dig-out and possibly a thicker build-up than a neighbour’s firm gravel on sandy soil. That extra dig is contingency, not the same as a 5% waste factor on the surface course. Keep those ideas separate in the Cost Estimator.

If you are placing gravel over a geotextile on a prepared sub-base, measure the finished gravel depth you want after rolling. Do not order for the excavation depth and the wearing course as if they were one layer.

Volume is length × width × depth in consistent units. The Gravel Calculator converts that into cubic yards or cubic metres and an approximate weight using a typical density for crushed stone. Density varies by rock type, grading, and moisture — treat weight as a planning figure for booking the tipper, then order against the supplier’s chart once you have a product name.

US yards and UK tonnes (metric tonnes) sit on different tickets. A “ton” in US conversation is not automatically a UK tonne. Ask the yard which unit they invoice and convert once on paper. The Sand Calculator is useful when you also need a blinding layer; do not reuse a gravel density for sharp sand.

If part of the job will later be a concrete apron or slab, keep that concrete volume in the Concrete Calculator. Gravel under a future slab is a sub-base line, not driveway wearing course — same rock family, different depth and purpose.

Angular crushed stone locks under tyres. Rounded pea gravel looks softer and migrates — fine for decorative beds, poor as the only layer on a primary drive. Many residential drives use a coarser base with a finer wearing course on top; each course has its own depth in the takeoff.

Ask what size the yard recommends for your climate and traffic. Freeze–thaw areas and steep gradients punish soft builds. Local practice beats a blog post written for a flat suburban lot in another region.

Edge restraints matter. Without timber, steel, or block edges, gravel creeps into lawns and the effective depth thins at the sides. That thinning shows up as ruts even when your average depth on paper looked fine.

Check access for the tipper. If material must be barrowed far from the drop point, labour can exceed the gravel cost. Narrow lanes, low trees, and weight limits on private bridges turn a cheap tonne into an expensive day.

Use the Cost Estimator with a local price per tonne or yard once you have volume. A national average is only a starting band. Add geotextile, edging, and hire of a plate compactor as separate lines so the rock price does not hide the job.

Stage the work: dig and dispose, lay fabric if specified, place and compact in lifts, then dress the surface. Ordering all the stone before the dig is finished is how people discover they needed a thicker base after the truck has gone.

If you want a hard washable surface for frequent car washing, or you already fight mud every winter, concrete or pavers may be the better long-term spend. Gravel is honest and repairable, but not maintenance-free.

Shared drives need a clear note on depth and product before anyone tips a load — a calculator will not settle a neighbour dispute about top-ups or runoff.