Construction Calculators

Gravel, crushed stone, and river rock all get estimated the same way: multiply the area you're covering by the depth in feet to get cubic feet, then divide by 27 to convert to cubic yards. That volume figure is the one most people picture when planning a project, but it isn't what a supplier actually sells. Nearly every rock yard prices and hauls material by the ton, so volume is just the middle step, not the final order number.

The link between volume and weight is density, measured in tons per cubic yard, and it varies by material. Plain gravel typically runs 1.4 to 1.7 tons per cubic yard, crushed stone shifts with rock type from about 1.3 tons for limestone up to 1.6 for granite, and river rock's rounded shape leaves more void space between stones, landing closer to 1.35 to 1.5 tons. Getting density right matters as much as getting depth right, since it drives the final tonnage and cost.

Each calculator on this site defaults to a typical density for its material, but a supplier's quoted figure is always more accurate, since it reflects the actual rock source, moisture, and size on delivery day. Overriding the default with that number before ordering is worth the extra step, particularly on a large driveway or dry creek bed where a small density error compounds into a real difference in tonnage and cost.

Every calculator here works out the loose volume and weight for the area and depth entered, and loose is the operative word. None of the three build in an allowance for compaction, spillage, or an uneven sub-base, all of which eat into the material actually installed. A driveway base course compacted with a plate tamper settles measurably below its as-spread depth, and spillage during placement or work around obstacles adds up on top of that.

A rough buffer of about 10 percent on top of the calculated tonnage covers most of that gap for a straightforward job, and it's the figure contractors commonly reach for when quoting a driveway, path, or bed. Irregularly shaped areas, sloped ground, or a project needing real compaction, such as a structural base under pavers, tend to sit toward the higher end of that range rather than the lower one.

It's worth checking whether a supplier's delivery quote already factors in a compaction allowance before adding a second buffer on top of theirs, since double-padding an order wastes money on unused material. For a base-and-surface project, running the calculator twice, once for the compacted base layer and once for the finer top layer on top of it, gives a more accurate combined total than estimating one blended depth in a single pass.

These three materials get confused constantly, but the difference comes down to shape and how they were produced, which determines what each is actually good for. Crushed stone is quarried rock mechanically broken and screened into a consistent angular grade, and that sharp, fractured shape locks together under compaction, which is why it's the standard choice for driveway bases, wall backfill, and any load-bearing, structural layer. Plain gravel overlaps with crushed stone in casual use but often covers a wider range of naturally weathered material.

River rock is naturally water-worn rather than crushed, collected and sorted to size instead of produced on demand, which is also why it costs noticeably more per ton than gravel or crushed stone. Its smooth, rounded shape doesn't interlock the way angular material does, so it stays mainly decorative, used in dry creek beds, borders, and ground-cover beds rather than anywhere carrying vehicle weight or needing a compacted structural base underneath it.

A practical rule: if the project is a driveway surface, a base layer, backfill, or drainage fill that needs to interlock and stay put, reach for gravel or crushed stone. If it's a decorative bed, a border, or a dry creek bed meant to look like a natural streambed, river rock fits better. Each calculator on this site defaults to density and pricing figures tuned to its own material, so using the matching one gives a more accurate estimate than adapting another material's numbers.