Gravel Volume Calculator: How Much Do You Need?

A gravel volume calculator works out how many cubic yards, cubic feet, or tons of gravel you need for a project based on the area’s length, width, and depth. You enter those three measurements (plus the gravel’s density if you want weight), and it returns the volume and estimated weight. This tool is essential for ordering the right amount of gravel for driveways, paths, flower beds, or drainage trenches—buying too little means a second delivery, and buying too much wastes money.

Formula

The calculator uses the basic volume formula for a rectangular prism:

Volume (ft³) = Length (ft) × Width (ft) × Depth (ft)

Because depth is usually measured in inches, convert it to feet first: Depth (ft) = Depth (in) ÷ 12. Then, to get cubic yards, divide the cubic feet by 27 (since 1 yard = 3 feet, and 3³ = 27). For weight in tons, multiply the volume in cubic feet by the gravel density in pounds per cubic foot, then divide by 2,000 (since 1 ton = 2,000 pounds).

Variables:

• Length – the longest side of the area, in feet (or meters).
• Width – the shorter side, in feet (or meters).
• Depth – how thick the gravel layer should be, in inches (or centimeters).
• Density – the weight of one cubic foot of gravel, typically 100–130 lb/ft³ (1,600–2,000 kg/m³).

Worked Example

Using the default values from the calculator above: length = 20 ft, width = 10 ft, depth = 4 in, density = 105 lb/ft³.

1. Convert depth to feet: 4 in ÷ 12 = 0.333 ft.
2. Calculate volume in cubic feet: 20 × 10 × 0.333 = 66.6 ft³.
3. Convert to cubic yards: 66.6 ÷ 27 = 2.47 yd³.
4. Calculate weight: 66.6 ft³ × 105 lb/ft³ = 6,993 lb.
5. Convert to tons: 6,993 ÷ 2,000 = 3.50 tons.

The calculator outputs 66.60 ft³, 2.47 yd³, and 3.50 tons—exactly matching the manual calculation.

When to Use a Gravel Volume Calculator

You need this calculator any time you plan to lay gravel over a flat, rectangular area. Common projects include:

• Driveways – typically 4–6 inches of compacted gravel base.
• Walkways and paths – usually 2–3 inches deep.
• Garden beds and mulch replacement – 2–4 inches for decorative gravel.
• French drains or trench backfill – depth varies, but often 6–12 inches.
• Patio bases – 4–6 inches under pavers.

If the area isn’t a perfect rectangle, you can divide it into smaller rectangles, calculate each, and sum the volumes. For circular areas (like a fire pit base), use the formula Ï€ × radius² × depth.

How to Choose the Right Gravel Depth

The depth you need depends on the gravel’s purpose and the base conditions. Too shallow and the gravel will shift or expose the soil; too deep wastes material and money.

• 2 inches – decorative mulch or light foot traffic only.
• 3 inches – standard walkways, patios, and play areas.
• 4 inches – driveways (for passenger cars) and heavy foot traffic.
• 6 inches – driveways that see trucks or frequent heavy loads.

If the ground is soft or poorly drained, you may need to add a geotextile fabric and increase the depth by 1–2 inches. Always compact the gravel in layers—if you’re going 6 inches deep, compact the first 3 inches, then add the rest.

Common Mistakes and How to Avoid Them

Even with a calculator, people often order the wrong amount due to a few recurring errors:

• Mixing units – Measure everything in the same system. If you measure length in feet, keep depth in feet (or convert inches to feet). Don’t multiply feet by inches directly.
• Forgetting to convert depth – Depth is often given in inches, but the formula needs feet. Divide by 12 first.
• Ignoring compaction – Gravel compacts about 10–20% when rolled. If you need 4 inches after compaction, you may need to order 5 inches of loose gravel. Most suppliers assume a 10% compaction factor, so ask.
• Rounding too early – Round only at the final step. If you round the depth to 0.3 ft instead of 0.333, your volume will be off by 10%.
• Not accounting for waste – Add 5–10% extra for spillage, uneven ground, or mistakes. It’s cheaper to have a little left over than to pay for a second delivery.

Understanding Gravel Density and Weight

Gravel is sold by volume (cubic yard) or by weight (ton). The density varies with the type of gravel and moisture content. Typical densities:

• Pea gravel – about 95–105 lb/ft³ (1,520–1,680 kg/m³).
• Crushed stone (#57 or #67) – about 100–110 lb/ft³ (1,600–1,760 kg/m³).
• Bank run gravel – about 110–125 lb/ft³ (1,760–2,000 kg/m³).

If you don’t know the exact density, 105 lb/ft³ is a reasonable average. But if you need a precise weight for transport or structural reasons, ask your supplier for the specific gravity of the material. Wet gravel can weigh 10–15% more than dry gravel.

Cost and Ordering Considerations

Gravel is typically sold by the cubic yard or by the ton. Prices vary widely by region and type, but you can estimate cost by multiplying the volume (in cubic yards) by the price per yard. Many suppliers have a minimum delivery fee, so it’s often more economical to order enough for the whole project at once. When comparing quotes, make sure you’re comparing the same volume and type of gravel—some suppliers quote by ton, others by cubic yard. Use the calculator to convert between them using the density.

Frequently Asked Questions

How many cubic feet are in a ton of gravel?

It depends on the gravel’s density. Using an average density of 105 lb/ft³, one ton (2,000 lb) equals about 19 cubic feet (2,000 ÷ 105). For lighter gravel (95 lb/ft³), that’s about 21 cubic feet; for heavier (125 lb/ft³), about 16 cubic feet. Always check with your supplier for the specific material.

Can I use the same calculator for sand or soil?

Yes, the volume formula is the same for any bulk material. The only difference is the density. Sand is typically about 100 lb/ft³, and topsoil about 80–100 lb/ft³. Just change the density value in the calculator.

How do I calculate gravel for a circular area?

Use the formula for the area of a circle (π × radius²) to get the square footage, then multiply by the depth in feet. For example, a 10-foot diameter circle has a radius of 5 ft, so area = 3.1416 × 25 = 78.54 ft². With 3 inches depth (0.25 ft), volume = 78.54 × 0.25 = 19.64 ft³, or 0.73 yd³.

Should I order by volume or weight?

Most landscaping suppliers sell by the cubic yard, while some gravel pits sell by the ton. If you’re ordering by weight, use the calculator to convert volume to tons using the density. If you’re ordering by volume, just use the cubic yard output. Always confirm the unit with the supplier before ordering.

How much extra should I order?

For most projects, order 5–10% extra to account for compaction, uneven ground, and spillage. For driveways, where compaction is significant, consider 10–15% extra. It’s better to have a small surplus than to run short and pay a delivery fee for a tiny additional amount.

What if my area isn’t a perfect rectangle?

Break the area into smaller rectangles, calculate each separately, and add the volumes. For irregular shapes, you can also use a string or hose to outline the area, then measure the longest and widest points, but this overestimates. The rectangle method is more accurate for most projects.

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in l | Length | ft | 20 | 0
in w | Width | ft | 10 | 0
in d | Depth | in | 4 | 0
in density | Gravel density | lb/ft³ | 105 | 0
out volume_ft3 | Volume | ft³ | l * w * (d / 12) | 2
out volume_yd3 | Volume | yd³ | (l * w * (d / 12)) / 27 | 2
out weight_tons | Weight | tons | ((l * w * (d / 12)) * density) / 2000 | 2