Stone calculator for Idaho

Stone is sold by the ton. For most grades, use about 2,800 lb per cubic yard, or 1.4 tons for each yard. This calculator accounts for the twelve graded materials available, starting with 3/8 inch chips and ending with 2.5 inch railroad ballast, using the weight assigned to the material selected. A contractor may have a spec number, while a homeowner may describe the work instead. The guide below matches both approaches to the material needed.

Calculation steps

1. For pads and driveways, get square footage by multiplying length by width in feet. For a drain, use trench length and trench width.
2. Choose depth based on the layer. Finish stone is usually 2-3 inches, base material is 4 inches, and French drains are 12 inches or deeper.
3. Divide cubic feet by 27 for cubic yards. Multiply yards by 1.4 to estimate tons for typical crushed stone.

Weight by stone type

Reading stone sizes

A grade identifies a rock-size range, with lower grade numbers meaning larger pieces. #4 measures 1-2 inches. For general drainage, driveways, and concrete work, #57 is 3/4 to 1 inch. #67 is finer at 1/4 to 3/4 inch and is regularly used for pipe bedding. #8 is around 3/8 to 1/2 inch; #89 goes from 3/8 inch down to fines. Those smaller grades suit paver joints and finish layers. Screenings contain chips and dust, forming a compactable bed for screeding. Railroad ballast uses angular rock measuring 1 to 2.5 inches for fast drainage and load support beneath tracks or equipment pads.

Clean stone or fines: choose by use

There are two material types here. Washed stone, including #57, has open spaces for water and belongs in drainage. Crusher run and road base contain fines, which let them compact for base layers. Putting either in the wrong application creates trouble: crusher run can trap water in a French drain, while a #57 driveway base can keep shifting. When a plan or permit lists a gradation, use the listed spec. If the product name is unclear, send the line item through our contact form. "3/4 clean" and "#57" may be different names for the same rock.

Common stone order sizes

Example: 30-foot French drain

For a trench measuring 30 feet long, 12 inches wide, and 12 inches deep, the volume is 30 cubic feet. That equals 1.1 cubic yards or 1.6 tons of #57. A 4-inch pipe in the center takes up only about 0.1 yards, so order all 1.6 tons and place the slight extra at the outfall. Put non-woven fabric in the trench before adding stone to stop soil from filling the open spaces needed for drainage.

Two ways to avoid ordering errors

• Use the spec first, then check the name used for it. Crusher run, crush and run, Pit Run, bank run, and unprocessed gravel are names for one product. #57 and "57s" mean the same stone.
• Plan for 5-10% compaction with rolled angular aggregate. Use the calculator's extra-percent setting for ordinary settling; engineered base work uses the specified compacted depth.
• Paver support comes from compacted base stone. Screenings or concrete sand make the thin leveling layer above it. Do not use dust by itself beneath pavers over soft soil.
• Calculate the trench volume and leave the pipe out of the math. Pipes below 6 inches generally reduce the material needed by less than a wheelbarrow load.

Crushed stone facts and figures

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