River Rock Calculator - Tons, Yards, and Total Cost

A river rock calculator turns an area sketch into the tons, cubic yards, and dollars you need to order, so a delivery arrives with exactly the right amount of stone and you avoid the common waste of over- or under-buying bulk aggregate. The tool combines your project shape, depth, and rock size into a single tonnage figure that matches how landscape suppliers price and deliver the material.

• • Decorative garden beds: Plan coverage for borders, xeriscape plantings, and tree rings where river rock is the visible mulch.
• • French drains and drainage runs: Size the gravel bed that surrounds perforated drain pipe, including the depth and width below the pipe.
• • Dry creek beds and swales: Estimate the tonnage needed for shallow channels that move runoff across a yard.
• • Walkways, paths, and patio borders: Order the right amount of rock for stepping-stone paths and patio edge accents.

Most homeowners and contractors buy river rock in bulk by the ton, and the density variation between 3/8 in pea gravel and 1-3 in river rock makes a calculator faster than mental math. Set a shape, depth, and rock size, and the river rock calculator does the cubic-yard and ton conversion for you.

If you are mixing river rock with other decorative stone like lava rock or Mexican beach pebbles, Landscape Rock Calculator covers the same shape-and-depth workflow across multiple rock types.

The river rock calculator follows the same area-times-depth-times-density formula that bulk aggregate yards use internally. It multiplies the chosen shape's square footage by the depth in feet, divides by 27 to convert cubic feet to cubic yards, and multiplies by the density of the selected rock size to get tonnage.

• Area: Square footage of the coverage zone. Rectangle uses length x width, circle uses pi x r^2, and triangle uses (base x height) / 2.
• Depth: Coverage depth in inches. Convert to feet inside the formula by dividing by 12.
• Density: Loose-compacted weight of the selected rock size in tons per cubic yard. Larger river rock sizes have lower density because of the void space between stones.
• Waste factor: Extra material percentage, usually 10% for decorative beds and 12 to 15% for drainage rock over uneven subgrade.

The waste factor is added at the end so the order covers spillage, settling, and uneven subgrade. Suppliers generally quote a 10% safety margin for decorative river rock and 15% for drainage beds where the subgrade is rarely level.

According to Omni Calculator, river rock tonnage is the area times depth in feet divided by 27 to get cubic yards, then multiplied by the rock density in tons per cubic yard.

If your project mixes river rock with crusher run or pea gravel, Gravel Calculator handles the same formula with different density presets for those materials.

Four ideas drive every river rock estimate: area, depth, density, and waste. Understanding them makes every other landscape aggregate estimate easier as well.

These four ideas also apply to most other landscape aggregates, so the same workflow covers pea gravel, crushed stone, and decorative lava rock.

When the project calls for crushed stone base under a flagstone patio, Crushed Stone Calculator applies the same area-depth-density model with a tighter density range.

Six short steps take you from a rough sketch to an order-ready tonnage figure that you can hand to a supplier or quote against.

1. 1 Pick the shape that matches your sketch: Choose rectangle, circle, or triangle. Only the fields for that shape stay visible, so the form stays uncluttered.
2. 2 Enter the length, width, diameter, or base and height: Use the longest run for length and the perpendicular run for width. For a circle, the diameter is the easiest measurement to take from a garden bed center.
3. 3 Set a realistic depth in inches: 2 in works for decorative beds, 3 to 4 in is typical for French drains, and 4 to 6 in suits dry creek beds that handle runoff.
4. 4 Choose the river rock size you are actually buying: 1-3 in is the most common decorative size; 3/8 in pea gravel suits tight spaces; 3-5 in river rock is reserved for drainage and large accent zones.
5. 5 Adjust the waste factor for your site: 10% is a safe default. Bump it to 15% if the subgrade is rough or you are filling around uneven flagstone.
6. 6 Enter the price per ton and read the tonnage: Use the delivered price from your landscape yard. The total cost multiplies the final tonnage by that price.

A 20 x 10 ft bed with 2 in of 1-3 in river rock, 10% waste, and a $110/ton delivered price comes out to 1.97 tons and about $216, which fits a single small dump-truck delivery.

When river rock is going into a French drain, the trench length, width, and pipe diameter matter as much as the surface area, and French Drain Calculator covers that geometry in detail.

A river rock calculator saves money on the order, time on the delivery, and rework at the site. These are the practical wins most users see in the first project.

• • Avoids short deliveries: A correct first order means you do not have to scramble for a second small-load delivery when the rock runs out halfway through the bed.
• • Stops over-ordering: Extra river rock is not returnable in most areas, so a tight estimate prevents the wasted cost of unused material sitting in the driveway.
• • Speeds up supplier quotes: Most landscape yards quote rock in tons or cubic yards. A tonnage figure is the fastest way to compare two or more suppliers.
• • Handles odd shapes: Circles around trees and triangular beds at property edges are common, and the calculator covers them with no extra math.
• • Plans truck and crew time: Knowing the tonnage ahead of time lets you schedule a single dump-truck drop and one crew day for spreading.

These benefits carry over to a property with multiple landscape rock zones, because the same inputs work for pea gravel, Mexican beach pebble, and crushed stone with one density swap.

If the river rock is going around a flagstone patio, Flagstone Calculator covers the stone tonnage for the patio surface, so both numbers come from the same planning session.

Four factors swing the final tonnage figure, and the limitations below explain where the calculator stays a planning tool rather than a bill-of-materials.

• • The calculator assumes a flat, level surface at the chosen depth. Sloped beds and dry creek channels actually hold more rock than the flat-area estimate suggests.
• • Bagged river rock has a different loose density than bulk delivery, and the bag weight listed by the manufacturer can be a better number for small bag orders.
• • Saltwater river rock and Mexican beach pebble have higher density than the standard washed river rock, so the calculator slightly under-orders those specialty stones.

Treat the calculator as a planning tool and round the final tonnage up to the nearest half ton. Most suppliers will drop a little extra at the end of a load rather than schedule a second short delivery.

According to Bama Aggregates, a ton of 1-inch river rock covers roughly 100 square feet at a 2-inch depth, and the same ton covers 75 square feet at a 3-inch depth.

If the river rock is going under a gravel driveway or beside a gravel walk, Gravel Driveway Calculator covers the deeper base depth and heavier compaction allowance that driveway rock needs.