Google Gravel Calculator: Volume & Cost

This gravel calculator works out the volume of gravel you need in cubic yards and cubic feet from the length, width, and depth of the area you want to cover. You enter the three dimensions in feet and inches, and it immediately returns the volume in both units, which you can then use to estimate how many tons to order. The calculator below uses the standard formula for a rectangular bed; for circular or oddly shaped areas, see the notes after the worked example.

Formula

The volume of a rectangular prism (which is what a gravel bed is, assuming flat ground and straight sides) is:

Volume (ft³) = length (ft) × width (ft) × depth (ft)

Since the calculator takes depth in inches, you first convert it to feet by dividing by 12. Then, to get cubic yards, you divide the cubic feet by 27 (because 1 yard = 3 feet, and 3³ = 27). Combining those steps into one expression gives:

Volume (yd³) = (length × width × (depth / 12)) / 27

Which simplifies to the formula used in the calculator: l × w × d / 324, where:

• l = length in feet
• w = width in feet
• d = depth in inches (the 324 comes from 12 × 27)

The second output, cubic feet, is simply l × w × d / 12.

Worked Example

Using the default values from the calculator: a 40 ft long, 25 ft wide area, with a 3-inch depth of gravel.

1. Convert depth to feet: 3 in ÷ 12 = 0.25 ft
2. Calculate volume in cubic feet: 40 × 25 × 0.25 = 250 ft³
3. Convert to cubic yards: 250 ÷ 27 = 9.26 yd³

The calculator’s first output shows 9.26 yd³ (rounded to two decimals), and the second shows 250.0 ft³. That matches the manual calculation.

Why Use Cubic Yards?

Gravel is sold by the cubic yard in most of the US, and by the tonne or cubic meter in many other countries. Knowing the volume in cubic yards lets you compare prices from different suppliers, because they all quote per yard. It also helps you plan delivery: a standard dump truck carries about 10–14 cubic yards, so a 9.26 yd³ order would fit in one truck with room to spare.

If you’re buying gravel in bags (common for small projects), each 0.5 ft³ bag covers about 2 ft² at 3 inches deep. For the 250 ft³ in the example, you’d need 500 bags—which is impractical, so bulk delivery is usually the better choice for anything beyond a small flower bed.

How to Choose the Right Depth

The depth you need depends entirely on the project:

• Path or walkway (2–3 in): enough for a stable surface underfoot.
• Driveway (4–6 in): must support vehicle weight; use compacted base gravel plus a top layer.
• Drainage or French drain (6–12 in): deeper to allow water to flow through.
• Under a shed or patio (4–6 in): provides a level, well-drained base.

Remember that gravel settles after installation, so it’s wise to add about 10% extra to your calculated volume to account for compaction and uneven ground.

Common Mistakes and How to Avoid Them

• Mixing units: the biggest error is entering depth in feet when the calculator expects inches, or vice versa. Always double-check the unit labels.
• Ignoring compaction: fresh gravel has air pockets; it settles by up to 10% after being walked on or driven over. Order extra.
• Forgetting slopes: if your area is not level, the depth varies. Measure the deepest point and the shallowest, and use an average for a rough estimate.
• Rounding too early: if you round the volume to 9 yd³ and then order, you might be short. Keep the decimals until you’re ready to order, then round up to the next whole yard.

Estimating Weight and Cost

Gravel weight varies by type, but a common rule of thumb is that 1 cubic yard of gravel weighs about 2,800 pounds (1.4 tons). For the example volume of 9.26 yd³, that’s roughly 26,000 pounds, or about 13 tons. To convert to metric: 1 cubic meter of gravel is about 1,680 kg (1.68 tonnes).

Cost per ton or per yard varies widely by region, type of gravel (crushed stone, pea gravel, river rock), and delivery fees. The calculator gives you the volume; you then multiply by the price per yard from your local supplier. For instance, if the price is $40 per yard, the example would cost about $370 before delivery.

When to Use a Different Formula

The rectangular formula works for most driveways, paths, and garden beds, but not for everything:

• Circular areas (e.g., a fire pit base): use the formula for a cylinder – Ï€ × radius² × depth. If your radius is 5 ft and depth is 4 in, that’s Ï€ × 25 × (4/12) = 26.18 ft³.
• Triangular areas: volume = (base × height / 2) × depth.
• Irregular shapes: break the area into rectangles, calculate each, and add them together.

For a very large or complex project, consider using a landscape professional’s estimate, as they account for slopes, compaction, and material waste.

Frequently Asked Questions

How many cubic feet are in a cubic yard?

There are 27 cubic feet in one cubic yard (3 ft × 3 ft × 3 ft). This is the key conversion for gravel volume.

How much gravel do I need for a 10×10 area?

At a 3-inch depth, a 10×10 area needs 10 × 10 × 0.25 = 25 cubic feet, which is 0.93 cubic yards (about 1 yard). At 4 inches, it’s 33.3 ft³, or 1.23 yd³.

Should I round up or down when ordering gravel?

Always round up to the next whole cubic yard, and add about 10% for compaction and waste. It’s cheaper to have a little extra than to run out mid-project and pay a second delivery fee.

What does “1 ton of gravel� cover?

One ton of gravel (about 0.7 cubic yards, depending on type) covers roughly 75 square feet at 3 inches deep, or 56 square feet at 4 inches. Use the volume to weight conversion for your specific gravel type.

Can I use this calculator for sand or soil?

Yes, the volume calculation is the same for any bulk material. However, weight per cubic yard differs: sand is about 2,700 lbs/yd³, topsoil about 2,200 lbs/yd³, so adjust your weight and cost estimates accordingly.

Why does the calculator show “Cannot compute� for some inputs?

That happens when the depth is negative or the length/width are zero, which would make a volume calculation impossible. The calculator is set to reject those inputs.

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in l | Lawn length | ft | 40 | 0 | 100000
in w | Lawn width | ft | 25 | 0 | 100000
in d | Depth | in | 3 | 0 | 120
out yd | Volume | yd³ | l * w * d / 324 | 2
out ft3 | Volume | ft³ | l * w * d / 12 | 1