How Much River Rock Do I Need? Coverage Chart, Tons Math & Project Table

The short answer

For the most common landscaping job — 1–2 inch river rock at 3 inches deep — one cubic yard covers about 108 square feet and weighs about 1.45 tons (typical US range). The formula behind every number in this guide is (length × width × depth ÷ 27) = cubic yards, then yards × tons-per-yard = tons. Depth is not a free choice: it follows the stone size, and the two work together in the table below. If you want to skip the arithmetic, the landscape rock calculator runs the whole chain with 10% overage built in.

Coverage by rock size: depth follows diameter

River rock sells by stone diameter, and the right bed depth is roughly 2–3 times the average stone diameter — deep enough to hide the ground (and any fabric) beneath, shallow enough that stones nest without shifting. Too thin and soil shows through; too thick and you are paying to bury expensive stone under more expensive stone. The table below gives typical depths, the coverage each cubic yard buys you at that depth, and what the size is best used for.

Coverage math for one yard: 27 ft³ ÷ depth-in-feet. At 3 inches (0.25 ft), 27 ÷ 0.25 = 108 sq ft per cubic yard. At 4 inches, 27 ÷ 0.333 = 81 sq ft. At 6 inches, 27 ÷ 0.5 = 54 sq ft. These are struck volumes — in the real world, rounded stones do not pack perfectly, so treat the result as the minimum order and add the calculator's 10% overage for settling and imperfect grading. For a dry creek bed specifically, see our dry creek bed rock guide, which accounts for the channel shape and spill margins that flat-area math misses.

The tons math: 1.45 vs 2.35 t/yd³ — know which line you are on

Here is the point where most people get surprised by their delivery ticket: “river rock” lives on two different density lines on this site, and which one applies depends on how the material is being sold to you.

In plain terms: 1 yd³ of river rock = 1.45 tons on the gravel line, or 2.35 tons on the rock line. The difference is real geology — dense rounded cobble packs tighter and heavier than the loose decorative blends many yards call “river rock.” When a supplier quotes per ton, confirm which density they use to convert: at 1.45 t/yd³, one ton is 27 ÷ 1.45 ≈ 18.6 ft³; at 2.35 t/yd³, one ton is 27 ÷ 2.35 ≈ 11.5 ft³. A quote of “$80 per ton” means very different coverage depending on the answer. When in doubt, order by the cubic yard — the volume you need is the volume your bed needs, regardless of what it weighs.

Worked project table

Common bed shapes run through the full chain: volume in ft³, cubic yards, and tons at the gravel-line 1.45 t/yd³ (in parentheses, the rock-line 2.35 t/yd³ figure the landscape rock calculator uses). All prices below are typical US ranges as of Oct 2026.

Check the lead row by hand: 30 × 3 × 0.25 = 22.5 ft³; 22.5 ÷ 27 = 0.833 yd³; 0.833 × 1.45 = 1.21 tons. On the rock line, 0.833 × 2.35 = 1.96 tons. Cost math: river rock runs about $50–$100 per ton bulk (typical US range, as of Oct 2026), so the 1.21-ton foundation bed lands around $60–$120 for the stone itself, plus delivery — suppliers commonly charge $50–$200 per load for a local drop (typical US range, as of Oct 2026).

Landscape fabric & edging: the prep that saves the rock

Landscape fabric goes down first, always. Rock without fabric sinks into soil within a season or two — mud migrates up, the stones disappear, and you end up buying the same rock twice. Use a woven fabric (not the thin spun-bond weed barrier, which tears under stone) and overlap seams by 6 inches. Cut X-shaped slits only where plants go through. Full detail — fabric types, stapling, and what goes under what stone — is in our landscape fabric under rock guide.

Edging keeps the bed a bed. Loose rock migrates: mowers fling it, rain washes it, feet kick it. Steel, aluminum, or concrete edging (installed 1–2 inches below the finished stone surface and an inch proud of the lawn) is what separates a $300 river rock bed from a $300 rock pile scattered across your grass. On slopes, edging doubles as the retaining lip that keeps the 2–4 inch stone from sliding — pair it with the deeper 3–4 inch bed from the coverage table above.

Ordering tips

Order by the yard, not the ton. Your bed needs a volume; tons are how the truck is weighed. If the yard quotes “river rock, $70/ton,” convert with their density — or with the 1.45 or 2.35 figures above — and compare against the bulk per-yard price ($50–$120/yd³ typical US range, as of Oct 2026) to see if the quote is fair. Round up to full yardsfor anything over 0.5 yd³ — half-yard minimums are common and the surcharge for a “partial” load erases the savings. Buy from a landscape supply yard, not bags, once you pass about half a cubic yard: the 0.833-yd³ bed above needs 45 half-cubic-foot bags at $5–$8 each ($225–$360) versus one bulk yard at ~$60–$120. And add 10% — the calculator does this by default — because graded beds always take more than the flat math says.

Common mistakes

Spreading 2–4 inch stone at 2 inches deep. The stones can't nest, fabric shows, and the bed looks thin and unfinished — use the size-depth pairing in the table above. Skipping fabric. The single most expensive shortcut: re-buying your rock in two years when it sinks. Ordering by weight from the wrong density line. Assuming 1.45 t/yd³ when the supplier ships at rock-line density leaves you short by over a third. No edging. Especially with mowers nearby — one season turns an unedged bed into a yard-wide scatter zone. Buying bagged rock for a whole bed. Bags exist for touch-ups; the bed deserves bulk pricing.