River Rock Calculator

Enter the bed size and depth and get the river rock you need in cubic yards, tons and bags, with the weight factor and its source shown.

Yard & GardenWorldwideSource: NM EMNRD conversion factors (from BLM Handbook H-3890-1)Free, no sign-up

Area shape

Units

Depth (in)

Length (ft)

Width (ft)

Or total area (ft², optional)

Overrides the shape when filled in.

Bag size (cu ft)

Printed on the bag; 0.5 is common.

Tons per cubic yard

1.42 = NM/BLM gravel ¼" – 2". Use your supplier's figure if you have it.

Extra allowance (%)

$ / ton

$ / bag

The default weight factor covers stone ¼–2 in. For cobbles larger than 2 in, enter your supplier's tons per cubic yard. The result updates as you type.

River rock needed

1.11 cubic yards · about 1.58 tons

30 cu ft = 60 bags of 0.5 cu ft · 0.85 m³ · 1.43 tonnes

Area covered	120 ft² (11.15 m²)
Volume	30 ft³ = 1.11 yd³
Weight at 1.42 tons/yd³	1.58 short tons (3,156 lb)
Bags	60 × 0.5 cu ft

What this page cannot tell you

The weight of your river rock. Tons depend on the stone's density, size and moisture, so a supplier's own tons-per-yard figure beats any table. The volume assumes an even depth over a flat area and does not allow for settling, a base layer or edging.

How to calculate how much river rock you need

Measure the bed. Length and width, a circle's diameter, or the total area.
Enter the depth. For river rock this is usually at least the size of the stones so the ground is covered.
Check the weight factor. 1.42 tons per cubic yard is the published row for gravel ¼–2 in; larger cobbles weigh differently, so use your supplier's figure for them.
Read yards, tons and bags. Add prices to compare a bulk load with bags.

10 situations where a river rock calculator helps

Dry creek bed

Work out the rock for a long, narrow channel by entering its length and average width.

Mulch replacement around a house

Measure each bed along the foundation and add up the volume before ordering.

Downspout splash areas

Small areas are easiest in bags; the count is ready for the store.

Comparing a delivered load

Quotes come per ton; the tons figure lets you compare suppliers.

Truck trips

The weight shows whether a pickup can haul it in one load or needs several.

Round tree rings

Use the circle shape and the ring's outer diameter, then subtract the trunk area if it matters.

Xeriscape conversions

Replacing a lawn with rock is a big order; the yards figure is what landscapers quote by.

Pond and water-feature edges

Estimate the decorative rock to finish the edge of a liner.

Budgeting before a design

Try depths and areas to see what the material alone will cost.

Metric projects

Enter metres and centimetres; get cubic metres and tonnes too.

Where the weight figure comes from

Volume is area × depth, with 27 cubic feet per cubic yard. Bags are the volume divided by the bag size printed on the bag, rounded up.

The default weight factor is 1.42 short tons per cubic yard, the 'Gravel ¼" – 2"' row of the New Mexico Energy, Minerals and Natural Resources Department's 'Conversion Factors for Construction Materials and Common Minerals', which states it is adapted from the BLM's Handbook for Mineral Examiners (H-3890-1). Small river rock and pebbles fall in that size range. Cobbles larger than 2 in are outside it — use the weight your supplier gives for the size you buy.

Limits: larger stones leave bigger voids and do not settle into a neat layer, so the volume for a given visible coverage is less certain than for small gravel. The result assumes an even depth on a flat area and does not include fabric, edging or a base layer.

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Sources

New Mexico EMNRD — Conversion Factors for Construction Materials and Common Minerals — Gravel ¼–2 in = 1.42 short tons per cubic yard (adapted from BLM H-3890-1)

Frequently asked questions

How much does a ton of river rock cover?

At 1.42 tons per cubic yard, a ton is about 0.70 cubic yards (19 cubic feet) — roughly 76 ft² at 3 in deep. Larger rock with different density will cover a different amount.

How many bags of river rock are in a yard?

54 bags of 0.5 cu ft, since a cubic yard is 27 cubic feet.

How deep should river rock be?

This page does not set a depth; it calculates the one you enter. Many people choose a depth at least equal to the stone size so soil does not show.

Is river rock heavier than pea gravel?

Both sit in the same published gravel row here. Real loads differ with the stone, the size mix and moisture, so use a supplier's figure for a firm weight.

Can I use it for large cobbles?

For volume, yes. For weight, replace the factor with your supplier's figure, because stones over 2 in are outside the published row used as the default.

Does it work in metric?

Yes — choose metres and centimetres.