Gravel & Mulch Depth Guide by Project Type
The right depth depends on the application — decorative gravel needs much less than a paver base or drainage bed. Using too little causes problems; using too much wastes material and money.
Decorative landscape gravel
2–3″Add landscape fabric underneath to suppress weeds
Garden mulch
2–3″Thicker than 3″ can suffocate roots; refresh annually
Walkway / footpath
3–4″Compact in 2″ lifts; edge restraints prevent spread
Paver base (under pavers)
4–6″ compactedMust be compacted with a plate compactor; skip pea gravel
Gravel driveway
4–6″For heavy use, go 6″+ and add a geotextile separator fabric
Drainage bed / French drain
6–12″DO NOT use pea gravel — must be angular for drainage flow
Retaining wall backfill
Full depth behind wallPrevents hydrostatic pressure buildup; drain to daylight
Raised bed fill base
2–4″ at bottomOptional drainage layer below soil in deep beds
Cubic yard quick estimate
1 cubic yard covers approximately: 100 sq ft at 3″ deep · 65 sq ft at 4½″ deep · 50 sq ft at 6″ deep. Use the Gravel Calculator for your exact area and depth.