Not all stone weighs the same, and buying by the ton while thinking in cubic yards is a common source of ordering errors. Crushed stone #57 and decomposed granite both sit around 1.5 tons per cubic yard. Limestone is slightly heavier at 1.6 tons per yard, while river rock comes in at 1.35. Lava rock is unusually light at 0.8 tons per yard because of its porous structure. For decorative coverage applications, a pea gravel estimate should use the 1.4 density figure rather than the crushed stone value, since the rounded particles pack together differently than angular aggregate.
Suppliers typically sell stone by the ton from quarries and by the bag from home improvement stores. Bulk stone ordered by the ton is almost always significantly cheaper for any project over a few square yards. When getting quotes, confirm whether the price is per ton or per cubic yard, because the difference for a 10-yard driveway project can be hundreds of dollars. If you are also grading or leveling the surrounding area, a dirt fill calculation alongside your stone order gives you the full materials picture before committing to delivery.
The depth you enter in the calculator has a direct impact on how many tons you need to order, and the right depth varies substantially by application. A gravel driveway supporting vehicle traffic needs a minimum of 3 to 4 inches of compacted top stone over a 4 to 6 inch compacted base layer; using 2 inches produces a surface that quickly displaces under tires and forms ruts. Decorative landscape beds and garden paths need only 2 to 3 inches of material, since they carry no structural load. French drain and drainage channel installations call for 4 to 6 inches of open-graded stone around the pipe to allow water infiltration without clogging.
For driveways and parking areas, only angular crushed stone (like #57, #21A, or #4 limestone) should be used as a top surface. Pea gravel and river rock are smooth and round and will not compact, so they migrate and fail under vehicle loads. Before placing any heavy stone delivery, use a square footage measurement of the project area to confirm your length and width inputs are accurate. A 1-foot error in either dimension at 3-inch depth changes your order by about 0.4 tons per 10 linear feet of coverage.