Gravel Calculator

The core idea is straightforward: figure out the volume of the space you need to fill, then convert that into a quantity you can order, usually cubic yards or tons. The tricky part is that most people measure in feet but suppliers sell by the yard, and weight varies by material. Getting those conversions right is where most people trip up.

Before you start, grab a tape measure and write down three numbers: the length of the area, the width, and how deep you want the gravel to sit. Depth is often underestimated. A decorative garden path might only need 2 inches, but a functional driveway base typically needs 4 to 6 inches of compacted gravel to hold up under vehicle traffic.

Once you have those three measurements in the same unit (feet work best to start), multiply them together to get cubic feet. From there, you convert to cubic yards and, if your supplier prices by weight, you convert again to tons using the density of your specific gravel type.

The volume formula is simple: Volume = Length × Width × Depth. All three measurements need to be in the same unit before you multiply. Feet is the most practical starting point for most projects.

Say you have a rectangular area that's 20 feet long, 10 feet wide, and you want 3 inches of gravel. That 3 inches needs to become feet first: 3 ÷ 12 = 0.25 feet. So the calculation looks like this:

• 20 ft × 10 ft × 0.25 ft = 50 cubic feet

For irregularly shaped areas, break the space into smaller rectangles, calculate each section separately, and add the totals together. An L-shaped driveway, for example, is really just two rectangles. Circles work differently: use the formula π × radius² × depth, where π is approximately 3.14159.

Always round your measurements up slightly rather than down. It's much easier to have a small amount left over than to come up short mid-project.

Gravel is almost always sold by the cubic yard, not the cubic foot. Since there are 27 cubic feet in one cubic yard (3 ft × 3 ft × 3 ft = 27), the conversion is simple division.

Cubic Yards = Cubic Feet ÷ 27

Using the example from above: 50 cubic feet ÷ 27 = approximately 1.85 cubic yards. You'd order 2 cubic yards to have a little breathing room.

This step catches people off guard because 27 feels like a big number. A project that sounds large in cubic feet often turns out to be just a yard or two of material. On the flip side, bigger projects add up fast. A 50-foot driveway at 4 inches deep can easily require 10 or more cubic yards.

Some suppliers price gravel by the ton rather than by volume, especially for larger bulk deliveries. To convert your cubic yard estimate to tons, you need to know the density of the gravel you're using.

Most gravel types fall somewhere between 1.4 and 1.7 tons per cubic yard. A common default used for general estimating is 1.5 tons per cubic yard, which works well for standard crushed stone or pea gravel.

Weight (tons) = Cubic Yards × Density (tons per cubic yard)

So if your project needs 4 cubic yards of standard crushed gravel:

• 4 × 1.5 = 6 tons

Denser materials like crusher run (also called road base) can weigh closer to 2 tons per cubic yard because the fines pack tightly together. Lighter decorative stones might come in under 1.4. When in doubt, ask your supplier for the specific weight of the material you're ordering. They deal with this question constantly and should be able to give you a density figure right away.

Coverage tells you how far a given quantity of gravel will spread at a particular depth. This is useful when you're working backward from a bag size or a bulk quantity and want to know if it's enough.

One cubic yard of gravel covers the following approximate areas depending on depth:

These numbers come from the same volume math: 1 cubic yard = 27 cubic feet = 46,656 cubic inches. Divide that by the depth in inches and you get square inches of coverage, which you convert to square feet by dividing by 144.

For bagged gravel, coverage is usually printed right on the bag. A typical 0.5 cubic foot bag at 2 inches deep covers about 3 square feet. Not much. Bagged gravel makes sense for very small patches; anything over 20 or 30 square feet usually becomes more cost-effective as bulk delivery.

Driveways are one of the most common gravel projects, and they require a bit more thought than a garden path. You're dealing with vehicle weight, drainage, and long-term stability, all of which affect how deep you need to go.

A standard recommendation for a gravel driveway is 4 inches of compacted depth for regular passenger vehicles. If you're parking heavy trucks or equipment, bump that up to 6 inches. Some installations also use a layered approach: a base layer of larger crushed stone (like #57 stone) topped with a finer surface layer (like crusher run or pea gravel).

For a typical two-car driveway, roughly 16 feet wide and 40 feet long:

• 16 ft × 40 ft × (4 ÷ 12) ft = 213.3 cubic feet
• 213.3 ÷ 27 = approximately 7.9 cubic yards
• At 1.5 tons per yard: roughly 11.8 tons

Round up to 8 or even 8.5 cubic yards to account for settling and any low spots. Gravel compacts when driven over, so what looks like enough on day one may look thin after a few weeks of use. Building in a 10% buffer on your order is a solid habit for driveway projects.

Not all gravel is the same, and the type you choose affects both how you use it and how you calculate the amount you need. Density is the big variable. A cubic yard of dense crusher run weighs noticeably more than a cubic yard of lightweight pea gravel.

Pea gravel is smooth and round, which makes it comfortable underfoot but also means it shifts around easily. It's popular for playgrounds and garden borders but not great for driveways where you need stability.

Crusher run compacts into a firm, almost solid surface when wet and rolled. It's the go-to for driveways and base layers precisely because those fines bind everything together. River rock is heavier per stone but has a lot of air between pieces, which gives it a lower bulk density. Decomposed granite lands in the middle and is popular for patios and paths in drier climates because it packs reasonably well and looks natural.

Here's a clean process you can follow for any gravel project, start to finish.

1. Measure your area. Get the length and width in feet. For odd shapes, break the area into rectangles and measure each one separately.
2. Choose your depth. Decorative paths: 2 inches. Garden borders: 2 to 3 inches. Driveways (light use): 4 inches. Driveways (heavy use): 6 inches.
3. Convert depth to feet. Divide your inch measurement by 12. Four inches becomes 0.333 feet.
4. Calculate cubic feet. Multiply length × width × depth (in feet). For multiple sections, add them all together.
5. Convert to cubic yards. Divide your cubic feet total by 27.
6. Add a 10% buffer. Multiply your cubic yard number by 1.1. This accounts for compaction, uneven ground, and minor waste.
7. Convert to tons if needed. Multiply cubic yards by the density of your chosen gravel type. When in doubt, use 1.5 as a default.
8. Contact your supplier. Give them your cubic yard or ton estimate and confirm the density of the specific material they carry. Ask if they have a minimum delivery quantity.

That's really all there is to it. The math isn't complicated; it's just easy to miss a conversion step or forget to account for depth in the right unit. Write each step down as you go and you'll end up with a number you can confidently hand to a supplier.