How this instrument works
Gravel — a loose aggregation of rock fragments, either naturally occurring or produced commercially as crushed stone — is used across construction and landscaping for everything from a driveway base to a garden path. It's typically sold and delivered by weight (tons), not by volume, so estimating a project's needs means converting the physical space you're filling into a volume first, then into the tons that conversion implies.
This instrument multiplies the area you're covering by the fill depth to get a volume in cubic feet, divides by 27 to convert to cubic yards (the unit gravel volume is conventionally measured in), and then multiplies by a density figure to get tons. All three steps happen from one set of inputs, giving both the cubic-yard volume and the tons-to-order figure at once.
Gravel density is a typical, adjustable figure, not a fixed constant — general gravel commonly runs somewhere around 1.4 tons per cubic yard, but the real range spans roughly 1.35 to 1.5 tons per cubic yard depending on the specific source, gradation, and how wet the material is when delivered. Always check with your specific gravel supplier for their product's density if precision matters, and adjust the default accordingly.
- Enter Area length (ft) and Area width (ft) — the footprint being covered with gravel.
- Enter Depth (in) — how thick a layer of gravel to spread; commonly 2-4in for a path, more for a load-bearing base.
- Enter Material density (tons/yd³) — defaults to 1.4, typical for bank-run gravel; real range is roughly 1.35-1.5 by source.
- Read Volume (cubic yards) and Gravel needed (tons) — both the raw volume and the tons most suppliers will actually quote and deliver by.
Worked example — a 20 ft × 10 ft path, 4 in deep
A 20 ft by 10 ft path or base area needs a 4in layer of gravel at a typical 1.4 tons per cubic yard density. Enter 20 into Area length (ft), 10 into Area width (ft), 4 into Depth (in), and leave density at 1.4. Volume comes to 20 × 10 × (4÷12) = 66.667 cubic feet, which is 66.667 ÷ 27 = 2.4691 cubic yards.
Gravel needed (tons) comes to 2.4691 × 1.4 = 3.4568 tons — the figure to give a gravel supplier when ordering delivery for this path.
Questions
Why does the calculator convert to cubic yards before converting to tons?
Because cubic yards is the conventional unit gravel volume is measured and often priced in, while tons is the unit most suppliers actually deliver and invoice by — going through cubic yards first makes the intermediate figure independently useful (for comparing against a per-cubic-yard price quote, for instance) rather than just a hidden step on the way to tons.
What gravel density should I use?
1.4 tons per cubic yard is a typical default for general bank-run gravel, but the real range commonly cited runs roughly 1.35 to 1.5 tons per cubic yard depending on the specific stone's source, size gradation, and moisture content at delivery. If your supplier can tell you their specific product's density, use that instead of the default for a more accurate tonnage.
How much depth of gravel do I need?
It depends on the project — a decorative garden path commonly uses 2-3in of gravel, while a load-bearing base under a driveway or patio often needs 4-6in or more, sometimes in multiple compacted layers. Check guidance specific to your project type, since a base layer meant to support vehicle weight needs meaningfully more depth than a purely decorative topping.
Should I order extra gravel beyond the calculated amount?
A small buffer is common practice — many suppliers and contractors add roughly 5-10% extra to account for compaction settling, uneven ground that needs more fill in low spots, and minor spillage during spreading. For a project where running short means a costly second delivery, rounding up your order slightly is often cheaper than the delay and delivery fee of ordering again.
Does gravel compact down after it's spread?
Yes, to some degree — loose gravel settles and compacts somewhat once it's spread, walked on, or driven over, especially if it isn't mechanically compacted during installation, meaning the finished depth can end up a bit less than what was originally spread. For load-bearing applications like a driveway base, mechanical compaction during installation is standard practice specifically to control this settling rather than letting it happen unevenly over time.