Question 1

How deep should gravel be for a driveway?

Accepted Answer

For a driveway, gravel should be laid at least 100mm (4 inches) deep on top of a compacted Type 1 sub-base. Use our Type 1 Sub-Base Calculator to work out sub-base quantities. Decorative driveways may use 50mm of decorative gravel over 100-150mm of sub-base. Without adequate depth, gravel will shift under vehicle weight and develop ruts.

Question 2

How much does gravel weigh per m³?

Accepted Answer

Gravel weight varies by type: loose decorative gravel is typically 1.5 tonnes per m³, pea gravel around 1.6 tonnes per m³, and driveway-grade angular gravel (20mm) around 1.8 tonnes per m³ once compacted (loose, it is closer to 1.6-1.7). Slate chippings are lighter at roughly 1.4 tonnes per m³, as slate is a flat, low-bulk-density stone. This gravel tonnage calculator uses the appropriate density for your chosen gravel type, and you can override it in the advanced options if your supplier quotes a different figure.

Question 3

What is the best gravel for a UK driveway?

Accepted Answer

Angular 20mm gravel (also called driveway aggregate or driveway shingle) is the most popular choice for UK driveways as it locks together under compaction. Golden gravel, cotswold stone, and granite chippings are all popular. Always lay gravel over a proper Type 1 MOT sub-base with a geotextile membrane to prevent mixing with the subsoil.

Question 4

How deep should decorative gravel be?

Accepted Answer

Decorative gravel for garden paths and borders should be 30-50mm deep. At 50mm depth, you get good coverage that stays in place and suppresses weeds. Always use a weed membrane underneath. For a solid paved surface instead, see our Paving Slab Calculator.

Question 5

Can I use this calculator for an L-shaped driveway or path?

Accepted Answer

Yes. Divide the L-shape into two rectangles, run the calculator for each one and add the results. Gravel is a loose material, so volumes and tonnages from the separate sections are simply additive: the summed figure is exact, with no cutting waste where the sections join (unlike paving or decking boards). Each section can have its own depth if, say, a parking area needs 100mm but a garden path only 50mm. When ordering bulk bags, add the volume or tonnage totals first and convert to bags once at the end, since each run rounds its bag count up and adding rounded counts can cost you an extra bag.

Question 6

How many bulk bags of gravel do I need?

Accepted Answer

A standard UK bulk bag (also called a dumpy, jumbo or tonne bag) holds roughly 800-850kg of gravel, which is about 0.5-0.566 m³ — not a full cubic metre. For a typical single-car driveway (3m x 6m at 100mm deep), the bare volume is 1.8 m³, which already needs about 4 bulk bags (1.8 ÷ 0.566 = 3.18, rounded up); adding the recommended 10% wastage gives 1.98 m³, still 4 bulk bags. This gravel quantity calculator works this out automatically using a 0.566 m³ bag by default, which you can change. For French drain gravel, see our French Drain Calculator.

Gravel Calculator — How Much Gravel Do I Need?

How We Calculate This

The formula

Gravel densities we use

Recommended depths

Frequently Asked Questions

Related Guides & Answers

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