Fill Dirt vs River Rock: Size, Cost, and Which to Use

Fill Dirt

Subsoil material free of organic matter, used for grading, filling, and raising elevation. Fill dirt is a lower-grade soil that lacks the nutrients of topsoil, making it ideal for structural and non-growing applications where settling must be minimized.

River Rock

River rock is naturally rounded stone from river beds and glacial gravel deposits, washed and screened into size bands from 3/4 inch to 8 inches. It costs $40 to $100 per ton in 2026, weighs 1.35 to 1.6 tons per cubic yard, and is the go-to decorative stone for dry creek beds, garden beds, borders, and drainage swales where the rock needs to look good and stay put. It costs two to three times what crushed stone costs because it is sorted and washed, and because the supply is limited to places with river gravel.

Fill Dirt

• ✓ Grading
• ✓ Filling depressions
• ✓ Raising elevation
• ✓ Backfill
• ✓ Construction site prep
• ✓ Under slabs

River Rock

• ✓ Landscaping
• ✓ Dry creek beds
• ✓ Decorative borders
• ✓ Drainage swales
• ✓ Water features
• ✓ Ground cover

Fill Dirt

• + Very affordable — often cheapest material available
• + Compacts firmly for structural support
• + Does not decompose or settle like organic soil
• + Widely available from construction sites
• + Ideal base under gravel or concrete

• − Not suitable for growing plants
• − Must be free of debris and contaminants
• − May contain clay that drains poorly
• − Needs compaction in layers for stability
• − Quality varies widely between sources

River Rock

• + Best-looking bulk stone, natural mixed colors
• + Never decomposes, one-time install
• + Drains fast and rarely clogs
• + Large sizes stay put in moving water
• + Available in sizes from 3/4 inch to 8 inch cobbles

• − Expensive, $40 to $100 per ton
• − Never packs, so it is a poor surface to walk or drive on
• − Heavy and awkward to spread
• − Holds heat in full sun
• − Hard to clean leaves and debris out of

Fill Dirt

Fine to coarse soil particles, free of organic matter like roots, grass, or leaves. Color ranges from tan to reddish-brown depending on local geology. "Clean fill" means free of debris, rocks larger than 3", and contaminants.

River Rock

River rock is sold by size band: 3/4 to 1 inch (sometimes called large pea gravel), 1 to 2 inch (egg rock), 2 to 3 inch, 3 to 5 inch, and 5 to 8 inch cobbles. Every piece is smooth and rounded. Colors are a natural mix of tan, brown, gray, cream, rust, and black, with regional loads that run mostly one shade. Single-color sorted rock costs more.