What's the difference between crushed stone and gravel?

Crushed stone is mechanically crushed and screened from quarried rock, so it's angular and interlocks tightly once compacted — that's why it's the standard choice for driveway sub-bases and foundations. Gravel is naturally rounded, worn smooth by water or weathering, and packs more loosely, which is why it shows up more in decorative surfaces and drainage beds than in load-bearing bases. Pick the matching density in this calculator's material dropdown either way.

What size crushed stone do I need for a driveway?

A #411-type driveway mix — stone with fines that compact into a tight, stable surface — at 10-15 cm (4-6 in) of compacted depth is the standard driveway sub-base. Larger, cleaner stone such as #57 drains better but doesn't lock together as tightly, so it's usually kept to a drainage layer beneath the sub-base rather than used as the sub-base itself.

How much crushed stone do I need for a French drain?

Enter the trench's length and width and the depth of clean stone you want around the drain pipe — commonly 15-20 cm (6-8 in) on each side and underneath it — and select an open-graded, fines-free grade like #57 so water can pass through freely. Keep the waste allowance low, since drainage stone generally isn't compacted the way a driveway base is.

Why is crushed stone more expensive in Gibraltar than in the UK?

Gibraltar has no significant local quarrying industry, so most bulk aggregate is imported, which adds shipping and handling costs on top of the base material price. Use this calculator's cost figure as a starting estimate, then confirm current pricing with a local builders' merchant since import costs can shift with shipping conditions.

What crushed stone do I need for a small garden path?

For a small path, a compacted sub-base of MOT Type 1 at around 7.5-10 cm depth, topped with a thinner decorative layer, is standard. Enter your path's length and width and that depth into this calculator to see whether you need a bulk order or just a few bags.

Crushed Stone Calculator | Hardcore & MOT Type 1 Volume, Weight & Cost — Gibraltar

How much crushed stone do you need?

Guessing at a crushed stone order usually ends one of two ways: the driveway sub-base comes up short and you're paying for a second delivery and callout, or you're left paying to haul away a pile of leftover stone. This crushed stone calculator works out the volume, weight and cost from three numbers you already know — the length and width (or diameter, for a circular area) of the space, and how deep you want the layer — for both rectangular jobs (driveways, parking pads, footing trenches) and circular or oval ones (tree rings, round patios, silo pads).

It's built around how crushed stone is actually bought and priced: by weight, not volume, and different grades pack to very different bulk densities. Pick a grade from the dropdown — #57 (clean 3/4 in drainage stone), #411 (a denser driveway/sub-base mix with fines), crushed granite, crushed limestone, or recycled concrete aggregate (RCA) — and the calculator applies that grade's density automatically, then adds a waste/compaction allowance so the tonnage you order matches what the job needs, not just the bare geometric volume.

How to use the crushed stone calculator

Pick the area shape — rectangular for a driveway, path or footing trench, or circular/oval for a tree ring, round patio base or silo pad.
Enter the length and width for a rectangular area, or the length and width as the two diameters of a circular/oval area (enter the same figure for both to get a plain circle).
Enter the depth of the crushed stone layer. Typical depths: 7.5-10 cm (3-4 in) for a footing or path base, 10-15 cm (4-6 in) for a driveway sub-base — more for heavier vehicle loads.
Choose a stone grade from the material dropdown — #57, #411, crushed granite, crushed limestone or RCA — or enter a custom density if your quarry quotes one.
Adjust the waste allowance if needed (10% by default), then read off the volume, weight and estimated cost. Change any input and the results recalculate instantly.

The crushed stone calculation, step by step

For a rectangular area, Volume = Length x Width x Depth. Keep the units consistent — if length and width are in metres and depth is in centimetres, convert the depth to metres (divide by 100) before multiplying.

For a circular or oval area, Area = pi x (Length/2) x (Width/2) — length and width act as the shape's two diameters, so entering the same value for both gives a plain circle's area. Multiply that area by the depth for volume, exactly as with a rectangle.

Crushed stone is bought by weight, so the next step adds the waste/compaction allowance to the raw volume, then converts to weight using the chosen grade's bulk density: Order quantity = Volume x (1 + waste%), and Weight = Order quantity x Density. Cost is the ordered weight multiplied by your supplier's price per ton.

Worked example: a driveway sub-base 6 m long x 3 m wide, 10 cm (0.1 m) deep, using #411 driveway mix (density 1,780 kg/m³) with a 10% waste allowance. Volume = 6 x 3 x 0.1 = 1.8 m³. With waste: 1.8 x 1.1 = 1.98 m³. Weight = 1.98 x 1,780 = 3,524 kg, or about 3.52 tonnes. At a typical $50 per ton, that's roughly $176 in material, before delivery.

Gibraltar crushed stone names: British terminology, imported materials

Gibraltar's builders' merchants use British trade terminology, reflecting the territory's UK-aligned supply chain: "MOT Type 1" for crushed-stone sub-base hardcore, and "20mm/10mm clean stone" for graded drainage aggregate. Because most aggregate is imported rather than quarried locally, prices tend to run higher than in mainland UK or nearby Spain.

Pro tips and common mistakes

At a typical Gibraltar price of around £48 per tonne, a driveway sub-base needing roughly 3.52 tonnes of MOT Type 1 (a 6 m x 3 m area at 10 cm compacted depth, with a 10% waste allowance) would cost approximately £169 in material, reflecting the territory's import-driven aggregate pricing.

Match the grade to the job. Clean, open-graded stone like #57 has no fines to clog, so it's the standard choice for French drains, foundation drains and leach fields; a driveway/crusher-run mix like #411 contains fines that lock together under compaction, which is exactly what you want under a driveway or parking pad and exactly what you don't want under a drain.
Compact in lifts on anything deeper than about 10 cm (4 in). A single thick lift, rolled once, compacts unevenly and settles later — two thinner layers, each compacted before the next goes down, hold up far better under vehicle loads.
Don't order a fines-heavy driveway mix for a drainage job. The fines that make #411-type stone compact so well are exactly what clogs the pore space a French drain or foundation drain relies on to let water through.
Order by weight, not by eye. Quarries price and load by the ton, so this calculator's weight output — not a guess at truck-bed volume — is what actually matches your order to the supplier's invoice.
Round up to a full load where you can. Suppliers often charge more per ton for an odd, non-round quantity than for rounding up slightly to their next standard truckload size.
Remember that depth means compacted depth, not the loose depth before rolling — loose crushed stone occupies noticeably more volume than the same material does once it's been rolled down.