Question 1

How much river rock do I need?

Accepted Answer

Multiply length by width by depth in feet, then by about 95 lb/ft³ and divide by 2,000 for tons. A 20 × 6 ft bed at 2 inches deep needs roughly 0.95 tons, or about two-thirds of a cubic yard.

Question 2

How deep should river rock be?

Accepted Answer

Two inches for decorative cover, three to four where you want weed suppression. Larger stone needs more depth simply to cover the fabric — 1-inch stone hides the ground at 2 inches, 4-inch stone does not.

Question 3

How much does a yard of river rock weigh?

Accepted Answer

Roughly 2,400–2,700 lb, or about 1.2–1.35 tons. Rounded stone weighs less per yard than crushed stone of the same nominal size because the round shapes leave more void space between them.

Question 4

How much area does a ton of river rock cover?

Accepted Answer

At 2 inches deep, about 125 square feet. At 3 inches, roughly 85 square feet. At 4 inches, about 63 square feet.

Question 5

Do I need landscape fabric under river rock?

Accepted Answer

Yes for a decorative bed on soil — it stops the stone sinking in and slows weeds. Use a woven geotextile rather than the thin plastic-film products, which tear and then float to the surface in pieces.

Question 6

River rock or mulch for landscaping beds?

Accepted Answer

Rock never needs replacing and does not blow away, but it stores heat, is hard to weed once seeds land in it, and is difficult to remove if you change your mind. Mulch feeds the soil as it breaks down but needs topping up annually.

Question 7

Can I use river rock for drainage?

Accepted Answer

Yes — it is a common choice for dry creek beds and French drain surrounds because the rounded shape keeps voids open. Use washed stone; unwashed material carries fines that silt up the voids and defeat the drainage.

Question 8

What size river rock is best?

Accepted Answer

One to three inches suits most beds — small enough to look intentional, large enough to stay put in rain. Reserve 3–5 inch stone for dry creek beds and erosion control where you need the weight.

River Rock Calculator

Inputs

Result

Diagram

Formula

References

Measure what the tool asks for

What it does with those numbers

Why it adds 5% waste

Choosing a stone size

Where the numbers come from

What this will not tell you

Related tools & materials

Calculators

Don't forget

Also useful

Frequently asked questions

Cite this page

Embed on your site