🏞️How much river rock does the bed need?

✓ Tested & verified Updated: Aug 6, 2026 How we calculate this

River rock calculator

Length ft

Width ft

Depth

Bag size

0.9 cubic yards≈ 1.3 tons

= 25 cu ft · about 50 bags (0.5 cu ft)

Weight, dry: 2,593 lb
Loads in a half-ton pickup: 2
One cubic yard covers: 108 sq ft at this depth

Bigger stone needs more depth. Below two stone diameters you will see fabric through the gaps.

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How much river rock do you need?

A 25 × 4 ft river rock border laid 3 inches deep takes 25 cubic feet — 0.9 cubic yards, or 1.3 tons. River rock is the heaviest common landscape stone at about 2,800 lb per cubic yard, so one ton is only 0.71 yards and covers roughly 77 sq ft at 3 inches.

Depth follows stone size, and this is where most orders go wrong. Small 3/8 to 3/4 inch rock covers at 2 inches; the common 1 to 3 inch grade needs 3 to 4 inches; 3 to 5 inch cobble needs 5 to 6 before the landscape fabric stops showing through the gaps. Order at the depth for your grade, not the depth on the coverage chart at the till.

It is also the material people most often underestimate the weight of. Two tons is a modest border and a full load for a 3/4-ton pickup — and moving it is a wheelbarrow at a time, because a shovel of cobble weighs what a shovel of mulch does times four.

The whole difficulty with river rock is that suppliers publish one coverage figure per ton and customers apply it to every stone size on the yard. Coverage is a function of depth, and depth is a function of how big the stone is — so the same ton covers 116 square feet as pebbles and 39 as cobble.

Work out your depth from the grade you are buying, then read across.

Depth	Covers per ton	Covers per cubic yard	100 sq ft weighs
2 in	116 sq ft	162 sq ft	1,728 lb
3 in	77 sq ft	108 sq ft	2,593 lb
4 in	58 sq ft	81 sq ft	3,457 lb
6 in	39 sq ft	54 sq ft	5,185 lb

That last row is a dry creek bed, and it is two and a half tons per hundred square feet. Check it against your vehicle before you offer to collect it.

Frequently asked questions

How much does a ton of river rock cover?

About 116 sq ft at 2 inches, 77 at 3 inches, 58 at 4 and 39 at 6, using 2,800 lb per cubic yard. Coverage per ton is the figure to compare quotes with, because a supplier selling by weight has no reason to volunteer that a bigger stone needs more depth and therefore covers less ground per ton.

How deep should river rock be?

Roughly two stone diameters. For 1 to 3 inch rock that means 3 to 4 inches; for pebble grades 2 inches will do; for 4 to 6 inch cobble you need 6 or more. Shallower than that and the fabric or soil shows through the gaps between stones, which is the single most common complaint about a finished rock bed.

Is river rock better than mulch?

For drainage swales, dry creek beds, downspout outfalls and anywhere a hose or a strimmer would shred organic mulch, yes. For planting beds, no — rock does not feed the soil, it radiates heat into shrub roots on a summer afternoon, and weed seed blows in and germinates in the dust that collects between stones just as happily as it does in mulch.

Do I need landscape fabric under river rock?

Yes, and a woven geotextile rather than a thin weed membrane. Rock is heavy and works its way down into soil; without separation you lose a visible depth of stone into the ground within a couple of seasons and end up topping up. The fabric is doing separation work first and weed control second.

How do I calculate a dry creek bed?

Treat it as a trench: average width × length × average depth, and remember the sides. A 20 ft creek bed 3 ft wide and 6 inches deep in the middle averages roughly 4 inches of stone across the width, so 20 × 3 × 0.33 = 20 cubic feet, or about 0.74 cubic yards — a ton, once you allow for the larger accent stones.

Can you walk on river rock?

Not comfortably at any depth, and not at all in the larger grades. Rounded 1 to 3 inch stone rolls underfoot and there is no way to build it into a stable surface. Use it where feet do not go, and put crushed stone or pea gravel on the routes people actually take.

How we calculate this

Volume is area × depth ÷ 12 ÷ 27; one cubic yard covers 162 sq ft at 2 inches, 108 at 3, 81 at 4 and 54 at 6. Weight uses 2,800 lb per cubic yard for 1–3 inch river rock from our density table, the working figure inside a published 2,600–3,000 lb range — 1.40 US tons per cubic yard, or 0.71 cubic yards to the ton. Coverage per ton is 2,000 ÷ 2,800 × 27 ÷ depth in feet. Depth guidance of roughly two stone diameters is standard aggregate practice for decorative rounded stone rather than a published standard.

Worked example

With Length ft 25, Width ft 4, Diameter ft 12, Base ft 20, Height ft 12, Area sq ft 300, Ring diameter ft 6, Gap around trunk (in) 4, Depth 3, Bag size 0.5 cu ft — Pea gravel, river rock, paver sand, this page works out 0.9 cubic yards ≈ 1.3 tons. = 25 cu ft · about 50 bags ( 0.5 cu ft )

Weight, dry2,593 lb
Loads in a half-ton pickup2
One cubic yard covers108 sq ft at this depth

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