Question 1

How much gravel do I need?

Accepted Answer

Divide your area by your required depth to get volume in m³, then multiply by the gravel density to get tonnes. This calculator does that automatically - just enter your area dimensions, depth and gravel type.

Question 2

How deep should gravel be?

Accepted Answer

For decorative garden borders, 40–50mm is typical. For paths, 50mm is a common minimum. For driveways, 50–75mm of decorative gravel over a compacted sub-base is standard. Deeper layers can feel unstable to walk on and require more material.

Question 3

How much is in a bulk bag of gravel?

Accepted Answer

A standard bulk bag (tonne bag) typically holds around 800–900kg of gravel, or approximately 0.5 m³. The exact weight depends on the gravel type and how the bag is filled. Always confirm the capacity with your supplier before ordering.

Question 4

Do I need a sub-base under gravel?

Accepted Answer

For decorative borders and garden areas, gravel can often be laid over weed membrane on existing soil. For driveways and paths where stability matters, a compacted sub-base of MOT Type 1 beneath the gravel is strongly recommended. Use our Sub Base Calculator and MOT Type 1 Calculator for sub-base quantities.

Question 5

What type of gravel is best for a driveway?

Accepted Answer

For driveways, a 10–20mm angular or crushed stone (such as shingle or granite chippings) tends to lock together better than rounded pea gravel, which can scatter. Self-binding gravel is another option for paths. The best choice depends on aesthetics and your preferred maintenance level.

Application	Typical depth	Notes
Garden border / decorative	40–50mm	Over weed membrane
Garden path	50mm	On firm compacted base
Driveway (decorative layer)	50–75mm	Over compacted sub-base
Drainage / soakaway	Varies	Consult drainage specialist

Gravel Calculator UK

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