River Rock Calculator
Measure your bed, pick a depth, and this river rock calculator converts square feet into the tons, cubic yards, and bags you actually order — extra for settling included.
Example: with Bed length (ft) 20 · Bed width (ft) 10 · Rock depth (in) 2 · Extra for settling (%) 10 → River rock needed: 1.83 tons.
Computed by the calculator below using its default values. Change any input to see your own numbers.
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Check it outHow much river rock do I need?
River rock is ordered by volume or weight, so convert your square feet first: cubic yards = sq ft × depth in inches ÷ 324. A 20 × 10 ft bed (200 sq ft) at 2 in deep needs 200 × 2 ÷ 324 = 1.23 yd³; add 10% for settling and low spots and you order about 1.36 yd³. At a typical 2,700 lb per cubic yard, that’s 1.83 tons — or 74 half-cubic-foot bags if you’re hauling from the garden center.
Depth is the decision that moves the bill. Lay rock about twice the diameter of the largest stones: 2 in works for 3/4–1 in pebbles, while 1–3 in river rock needs 3–4 in to hide the ground and stay put. Coverage per ton shrinks fast as depth grows — roughly 120 sq ft at 2 in but only 80 sq ft at 3 in — so price both the depth you want and the one you can live with.
How it’s calculated
Volume = length × width × (depth ÷ 12) in cubic feet, divided by 27 for cubic yards — equivalently sq ft × depth-in ÷ 324 — then increased by your extra-for-settling percentage. Tons assume river rock at 2,700 lb (1.35 tons) per cubic yard, a mid-range figure; actual stone runs roughly 2,400–2,900 lb per yard depending on size and moisture, so confirm with your supplier. Bag count divides the adjusted cubic feet by 0.5 and rounds up.
Results update as you type and are estimates, not professional advice — verify important decisions with a qualified professional.
Common mistakes
- Pricing by square feet alone — 200 sq ft at 4 in is twice the rock of 200 sq ft at 2 in; depth drives the order.
- Assuming a ton covers a fixed area — coverage depends entirely on depth (about 120 sq ft at 2 in, 80 sq ft at 3 in).
- Ordering the exact math with no extra — rock settles into soil and uneven grade; 10% spare beats a second delivery fee.
Frequently asked questions
How much river rock do I need for 100 square feet?
At 2 in deep: 100 × 2 ÷ 324 ≈ 0.62 cubic yards, or roughly 0.83 tons at 2,700 lb per yard. Double the depth and both numbers double.
How many square feet does a ton of river rock cover?
About 120 sq ft at 2 in deep and 80 sq ft at 3 in, assuming 2,700 lb per cubic yard. Larger, chunkier stone packs less densely and covers a bit more.
How deep should river rock be?
Roughly twice the size of the largest stones: 2 in for 3/4–1 in pebbles, 3–4 in for 1–3 in river rock. Too shallow shows soil and scatters underfoot.
Should I buy river rock in bags or bulk?
A cubic yard equals 54 half-cubic-foot bags, so bulk delivery usually wins past about half a yard. Bags make sense for small accents and touch-ups.
Is river rock sold by the ton or the yard?
Both. Landscape yards typically weigh loads in tons; bagged rock is by volume. This calculator reports each so you can compare quotes directly.