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River Rock Calculator

A river rock calculator works out how much decorative river rock you need — in cubic yards, tons and bags — for beds, borders, dry creek beds and drainage, from the area and depth.

Your measurements

Result

River rock is larger and heavier than pea gravel, so it needs a touch more depth to cover the ground, and always a fabric layer beneath to keep it weed-free.

How it is calculated

Volume = area × depth, in cubic yards. Tons use ~1.35 tons per cubic yard for river rock; larger, denser stone weighs more. Bigger cobble needs more depth to fully cover the soil.

Steps

Enter the area, or length and width.
Set the depth — 2-3 in for most beds, more for larger cobble.
Read the cubic yards and tons for a bulk order.
Lay landscape fabric first.
Order a little extra for topping up.

Worked example

A 200 sq ft bed at 2 in deep needs about 1.23 cubic yards of river rock — roughly 1.7 tons.

Common questions

How deep should river rock be?

About 2-3 in for typical 1-2 in rock; larger cobble needs more to hide the ground beneath.

How much does river rock weigh?

Around 1.35 tons per cubic yard, a touch lighter than crushed gravel because the stones are rounded.

Do I need fabric under river rock?

Yes — landscape fabric blocks weeds and keeps the rock from mixing into the soil.

River rock or pea gravel?

River rock is larger and decorative; pea gravel is small and good underfoot. The calculation is the same — just the depth and look differ.