How Deep Should Gravel Be?

Gravel depth depends on the load it needs to support and its purpose. Too thin and it shifts or sinks; too thick wastes money. Here are the correct depths for every common project.

Depth guide by project

Project	Minimum depth	Recommended depth
Decorative landscape path	2”	3”
Pedestrian walkway	3”	4”
Patio base (pavers)	4” compacted + 1” sand	5” + 1” sand
Patio base (concrete)	4”	6”
Residential driveway	6”	8” (base + surface)
Commercial driveway	8”	12”
French drain	Fill trench	12”–18” deep trench
Around foundation	3” slope away	4” with fabric
Horse arena / paddock	3”	4”–6”

Why depth matters

For driveways

Insufficient base depth is the leading cause of driveway ruts and potholes. The gravel compacts under traffic and displaces laterally. A minimum 4-inch compacted base absorbs load and resists movement.

For patios and pavers

A 4-inch compacted gravel base prevents settling and frost heave. Skip this and your pavers will shift after the first winter freeze-thaw cycle.

For drainage

Depth increases the volume of void space that stores and moves water. Shallow gravel in a drainage trench fills up faster and fails sooner.

How to calculate gravel volume

Volume (cu yd) = Length (ft) × Width (ft) × Depth (in) ÷ 324

Or use the Gravel Calculator — enter your dimensions and depth, and it outputs cubic yards, tons, and bags.

Coverage at different depths

Depth	1 cubic yard covers
2”	162 sq ft
3”	108 sq ft
4”	81 sq ft
6”	54 sq ft
8”	40 sq ft
12”	27 sq ft

Compaction factor

Gravel compacts 10–15% after installation. Order 10–15% extra for projects requiring compacted depth:

Driveways: order 12% extra
Patio bases: order 10% extra
Paths: usually not necessary

Frequently Asked Questions

How deep should gravel be for a driveway?

A residential driveway needs 4–6 inches of compacted gravel base plus 2–3 inches of surface gravel, for a total of 6–9 inches. High-traffic or heavy vehicle areas need 8–12 inches of base.

How deep should gravel be under a patio?

For a paver or flagstone patio, use a 4-inch compacted gravel base plus a 1-inch sand layer. For a concrete patio, use 4–6 inches of compacted gravel sub-base.

How deep should pea gravel be for a path?

Landscape paths with pea gravel should be 2–3 inches deep for decorative use. For a more stable, weed-resistant path, use 3–4 inches over landscape fabric.

How much gravel do I need to fill a hole?

Volume (cu yd) = Length (ft) × Width (ft) × Depth (ft) ÷ 27. Use the Gravel Calculator with the exact dimensions for an instant result in cubic yards and tons.

Does gravel depth affect drainage?

Yes — deeper gravel provides better drainage and load-bearing capacity. Under slabs and driveways, inadequate depth is the most common cause of settling and cracking.