Rock size is the first decision in any rock project, because the size sets what the material can actually do. Smaller rock and fines compact firm and work for paths and tight ground cover. Bigger rock stays loose, drains hard, and does the heavy work of slopes and drainage. The larger the stone, the deeper you spread it and the more likely you want weed fabric underneath. Here is a walk through the common sizes and what each is for.
The common landscape rock sizes
Fines and decomposed granite. The smallest material, granite broken down to particles and dust. It compacts into a firm, natural surface, which makes it the go-to for paths, patios, and seating areas rather than a decorative top layer.
3/8 inch pea gravel. Small, rounded stones about a quarter to half an inch. Comfortable underfoot, easy to spread, and a clean look for paths, play areas, and filling between steppers. It does shift a bit because the stones are round. See our guide to landscaping with pea gravel.
3/4 inch crushed gravel. Angular stones a bit under an inch. The angles let it lock together, so it stays put better than pea gravel and works well as a path top, a base layer, or general ground cover.
1 to 2 inch cobble and river rock. Smooth, rounded stones in the one to two inch range. A popular decorative size for beds, borders, and dry creek beds, big enough to read as stone but still easy to place. Our guide to landscaping with river rock and pebble has more.
3 to 8 inch rock. Hand-sized and larger stones used as bold accents, in larger dry creek beds, and for ground cover where you want a chunky, low-maintenance look. Too big to walk on comfortably, so it is a feature, not a surface.
Rip rap. Large, angular broken stone built for slopes, shorelines, channels, and erosion control. It is sized to stay put under moving water and hold a grade. See our collection of rip rap.
Boulders. The largest pieces, used as standalone features, retaining accents, and focal points. Our guide to landscaping with boulders covers placement and sizing.
Size to use and depth
| Size | Typical use | Recommended depth |
|---|---|---|
| Fines / decomposed granite | Paths, patios, seating areas | about 2 to 3 inches |
| 3/8 inch pea gravel | Paths, play areas, between steppers | about 2 to 3 inches |
| 3/4 inch crushed gravel | Path top, base layer, ground cover | about 2 to 3 inches |
| 1 to 2 inch cobble / river rock | Beds, borders, dry creek beds | about 2 to 3 inches |
| 3 to 8 inch rock | Accents, larger dry creek beds, chunky cover | about 3 to 5 inches |
| Rip rap | Slopes, shorelines, erosion control | varies; size to the application |
| Boulders | Features, focal points, accents | set individually, partly buried |
Depths are approximate. Bigger rock generally needs more depth so the soil does not show through the gaps between stones, and at that point weed fabric underneath is worth it because you cannot compact large rock to choke out weeds the way you can with fines.
Picking the right size for the job
- A surface you walk on: stay small. Fines, pea gravel, or 3/4 inch crushed gravel give you a comfortable, firm path.
- A decorative bed or border: 1 to 2 inch river rock or cobble reads as stone without being clumsy.
- Drainage or a dry creek bed: mix sizes, larger stone in the channel with smaller rock around it. See how to build a dry creek bed.
- Slopes and erosion: rip rap, sized to the water and grade.
- A focal point: one or a few well-placed boulders.
For a fuller breakdown of stone types and looks, our landscape rock types guide is the companion to this size guide.
How much you need
Smaller rock is usually spread about 2 to 3 inches deep and larger rock a bit deeper, so coverage depends on both your area and the size you pick. Rather than estimate, run your numbers through the coverage calculator for an exact quantity before you order.
Frequently asked questions
What landscape rock size is best for a walking path?
Smaller material. Decomposed granite fines, 3/8 inch pea gravel, or 3/4 inch crushed gravel all give a comfortable, firm path. Larger rock is loose and uncomfortable underfoot, so it is better as decoration than as a surface.
How deep should I spread landscape rock?
Smaller rock is usually about 2 to 3 inches deep. Larger rock, in the 3 to 8 inch range, generally needs roughly 3 to 5 inches so the soil does not show through. These are approximate, and the calculator confirms quantity for your depth.
Do I need weed fabric under landscape rock?
It helps most under larger decorative rock, where you cannot compact the stone to suppress weeds. Under fines or DG that you compact firm, fabric is less critical but still common. Bigger rock plus fabric is the usual pairing.
What size rock is used for drainage?
Drainage usually wants larger, angular rock that lets water move freely, often 3/4 inch crushed gravel up through cobble and rip rap depending on the job. A dry creek bed typically mixes sizes, with larger stone in the channel.
What is rip rap used for?
Rip rap is large, angular stone used on slopes, shorelines, and channels to control erosion. It is sized to stay in place under moving water and hold a grade, which smaller decorative rock cannot do.
Get the materials
Browse landscape rock, river rock, pea gravel, rip rap, and boulders to match the size to your project. Size the job with the coverage calculator. We deliver nationwide from our California yards.