Work out how much gravel, slate or decorative chippings you need for paths, driveways and borders — and whether to add stabilising grids and a weed membrane underneath.
Allow 10 litres per m² per centimetre of depth. Paths usually want 4–5cm of gravel; driveways need 10cm or a grid system to stop rutting.
01 — The Calculator
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5 cm
Depth changes the volume a lot — 5cm mulch is normal, raised veg beds want 20cm+.
Not sure? See the depth guide belowWhy allow extra? See why soil settles after laying
Worked example: garden path
A path 4m × 1m at 5cm deep needs 4 × 5 × 10 = 200 litres. That's 8 handy 25L bags, or well within one bulk bag if you're covering a larger area — the calculator prices both.
Depth depends on the job: 30–40mm is plenty for footpaths and decorative beds, while driveways and parking areas need 50mm or more so the sub-base never shows through. Whatever the project, never lay shallower than twice the stone size — 20mm gravel wants at least 40mm of cover or it scuffs bare within weeks. On beds, always put down a weed membrane first; on driveways, use a proper geotextile over compacted MOT Type 1 instead, which adds strength as well as weed control.
Add 5–10% for wastage and settlement, and remember gravel compacts into hollows on driveways, so keep a spare bag for top-ups. Gravel weighs about 1.6 tonnes per cubic metre — one bulk bag covers roughly 12–14m² at 50mm deep. Angular stone locks together and stays put on slopes and drives; rounded pea gravel is kinder underfoot but migrates, so it needs firm edging to contain it. Order all the stone in one delivery so the colour and size batch match across the whole area.
4–5cm is enough for footpaths. Driveways need around 10cm, ideally laid over a compacted MOT type 1 sub-base.
Last reviewed: October 2026 · Reviewed by the Garden Calculator editorial team.
Garden Calculator — Project
My garden project · 26 October 2026
| Item | Qty | Each | Total |
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Prices from the Garden Calculator sample trade catalogue — confirm with your merchant before ordering.