Enter your area length, width and depth to get the aggregate volume in cubic metres - plus the tonnes to order and how many bags to buy. Covers decorative gravel, MOT Type 1 and hardcore sub-base, ballast and drainage stone. Works in metres and centimetres.
Typical depths: 50–75 mm (2–3 in) for mulch, 40–50 mm for decorative gravel, 100 mm (4 in)+ for new topsoil, deeper again to fill a raised bed. Each area can take its own depth.
Enter the delivered price per m³ of bulk material to get the total.
Total bed area
10.00 m²
In litres
500 L
Got your numbers but want someone to do the work? Find trusted local handymen and tradespeople in the UK on ukhandyman.directory.
Gravel is spread to an even depth, so the amount you need is the area times the depth:
volume = length × width × depth
The calculator reports that volume in cubic yards or cubic metres (and litres or cubic feet), then divides by the size of one bag to give the number of bags. Covering a driveway plus a separate path? Add an area for each and the volumes pool into one order. All math runs in exact metric internally, so switching units never changes the answer.
This example follows the unit system you pick in the calculator above.
A 10 m × 3 m driveway at 100 mm deep, ordered in bulk:
| Job | Depth | Notes |
|---|---|---|
| Decorative / pea gravel | 40–50 mm (1.5–2 in) | Over a weed membrane |
| Path or patio top layer | 50 mm (2 in) | Over a compacted base |
| Driveway (gravel layer) | 100–150 mm (4–6 in) | Over a separate sub-base |
| French drain | full trench depth | Around the drainage pipe |
Multiply the driveway area by the sub-base depth. A 10 m × 3 m driveway with a 150 mm MOT Type 1 sub-base needs about 4.5 m³ - roughly 9 tonnes, as Type 1 compacts to around 2 tonnes per cubic metre. Enter your size and depth above. Remember the sub-base is a separate layer under the surface gravel, tarmac or block paving.
MOT Type 1 is a graded crushed limestone or granite to a Department for Transport specification - the stone sizes are mixed so it locks together and compacts to a solid base. Hardcore is a looser term for any coarse fill (often crushed concrete or brick) used to build up a level before the sub-base. For a driveway or shed base you want MOT Type 1; hardcore is for bulk filling.
For a garden path or patio, 100 mm of compacted MOT Type 1 is usually enough. For a driveway that takes a car, use 150 mm; for heavier vehicles, 200 mm. Lay and compact it in 75 mm layers rather than all at once. Set your depth in the calculator to match, and calculate the surface layer separately.
Roughly 1.4–1.7 tonnes per cubic metre for gravel and around 2 tonnes for compacted MOT Type 1. Aggregate is usually sold by weight - bulk bags are typically 800 kg ("a tonne bag" is often under a tonne), and loose loads are ordered by the tonne. Get the volume from the calculator, then ask your supplier for their weight per cubic metre.
Ballast is a mix of sharp sand and gravel used to make concrete - not a sub-base material. Typical concrete is 1 part cement to 5 parts ballast. If you are mixing concrete rather than laying a base, work out the volume here and use the concrete calculator for the cement and ballast split.
Bulk bags suit small jobs and are easy to place with a crane-off delivery. For a driveway or any large area, a loose tipped load by the tonne is considerably cheaper per tonne - but you need somewhere to tip it and a barrow to move it. The calculator gives both a bag count and a bulk volume so you can compare.
Volume and bags to cover beds with bark chippings or mulch at any depth.
Open calculator→Volume, litres and bags of topsoil for lawns, turf and garden beds.
Open calculator→Cubic volume and bags of concrete for slabs, footings, pads and posts.
Open calculator→Blocks, caps and gravel base for a retaining wall, from your wall and block sizes.
Open calculator→Rolls and pallets of turf, or kilos and bags of grass seed, from your lawn size.
Open calculator→Sprinkler heads, flow and the number of zones to plumb, from your garden size and water supply.
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