Gravel Fill Calculator: How Much Gravel Do I Need?

This gravel fill calculator tells you exactly how many cubic yards, cubic feet, or tons of gravel you need for a rectangular, circular, or irregularly shaped area. You enter the dimensions (length, width, depth) and the gravel density, and it returns the volume and weight required for your project. The calculator uses the standard formula: Volume = Length × Width × Depth, then converts to weight based on the gravel’s density.

Formula

The core formula for gravel volume is:

Volume (cubic feet) = Length (ft) × Width (ft) × Depth (ft)

Since depth is often given in inches, convert it to feet first: Depth (ft) = Depth (in) ÷ 12.

To get cubic yards, divide cubic feet by 27 (since 1 cubic yard = 27 cubic feet). To get weight in tons, multiply the volume (in cubic feet) by the density (in pounds per cubic foot), then divide by 2000 (since 1 ton = 2000 pounds).

Variables:

• Length (L) – the longest horizontal dimension of the area, in feet (or meters).
• Width (W) – the horizontal dimension perpendicular to length, in feet (or meters).
• Depth (D) – how thick the gravel layer will be, in inches (or centimeters).
• Density (Ï�) – the mass per unit volume of the specific gravel type, typically 95–135 lb/ft³ (1,520–2,160 kg/m³).

Worked Example

Using the default values from the calculator: Length = 10 ft, Width = 5 ft, Depth = 3 in, Density = 105 lb/ft³.

1. Convert depth to feet: 3 in ÷ 12 = 0.25 ft
2. Calculate volume in cubic feet: 10 × 5 × 0.25 = 12.5 ft³
3. Convert to cubic yards: 12.5 ÷ 27 ≈ 0.46 yd³
4. Calculate weight: 12.5 × 105 = 1,312.5 lb
5. Convert to tons: 1,312.5 ÷ 2000 = 0.65625 tons ≈ 0.66 tons

The calculator shows 12.50 ft³, 0.46 yd³, and 0.66 tons – matching the manual calculation.

When to Use This Calculator

You need a gravel fill calculator for any project that involves laying a loose aggregate base. Common scenarios include:

• Building a driveway or parking area – typical depth is 4–6 inches of compacted gravel.
• Creating a walkway or patio base – usually 2–3 inches of gravel under pavers.
• Filling a trench for drainage or utility lines – depth varies based on pipe size and local codes.
• Landscaping beds or French drains – often 3–4 inches of gravel.
• Estimating material for a gravel pit or foundation base.

If you’re ordering from a supplier, they typically sell gravel by the cubic yard (for bulk) or by the ton (for weight-based pricing). This calculator gives both, so you can compare quotes accurately.

How to Choose the Right Gravel Type and Density

Gravel density varies significantly by type and moisture content. Here are typical densities (in lb/ft³) for common gravels:

• Pea gravel: 95–100 lb/ft³
• Crushed stone (limestone): 100–110 lb/ft³
• Bank gravel (with sand): 105–120 lb/ft³
• Granite gravel: 110–130 lb/ft³
• Recycled concrete: 100–120 lb/ft³

If you don’t know the exact density, 105 lb/ft³ is a reasonable average for mixed gravel. For wet conditions, add 5–10% to the density to account for moisture. When ordering, tell the supplier the volume you need; they will convert to tons using their own density figure, which may differ slightly.

Common Mistakes and How to Avoid Them

The most frequent errors in gravel calculation are:

• Mixing units – Always convert all measurements to the same unit (feet or meters) before multiplying. A depth of 6 inches is 0.5 feet, not 6 feet.
• Forgetting compaction – Gravel compacts by about 10–20% under a compactor. If you need a final depth of 4 inches, you may need to order 10–20% more to account for settling. For driveways, order 10% extra; for walkways, 5% extra is usually enough.
• Ignoring irregular shapes – For circular areas, use the formula Ï€ × (radius)² × depth. For irregular shapes, divide the area into rectangles and circles, calculate each, and sum them.
• Rounding too early – Round only at the final step to avoid accumulating errors. The calculator shows two decimal places, which is sufficient for ordering.

Limits of the Formula

The volume formula assumes a flat, uniform depth. Real-world surfaces are rarely perfectly level, so add a buffer. Also, the density is an average – actual density depends on the specific gravel source, moisture, and compaction. The weight calculation is an estimate; for critical structural projects (like building foundations), consult an engineer. The calculator does not account for wastage during spreading or loss to wind and rain, so a 5–10% overage is standard practice.

Alternatives: How to Order Without a Calculator

If you don’t use this calculator, you can estimate manually:

• Measure the area (length × width) in feet.
• Decide on the depth in inches, convert to feet.
• Multiply to get cubic feet, then divide by 27 to get cubic yards.
• For tons, multiply cubic yards by 1.4 (average weight of gravel per cubic yard in tons) – but this is a rough estimate. Better to call your supplier and ask for their specific conversion.

Many suppliers have their own calculators, but using this one gives you an independent check. Remember that ordering too little means extra delivery fees; ordering too much means wasted money and material.

Frequently Asked Questions

How many cubic feet are in a ton of gravel?

It depends on the density. At 105 lb/ft³, one ton (2000 lb) equals about 19 cubic feet. At 120 lb/ft³, it’s about 16.7 cubic feet. Use the formula: cubic feet = 2000 ÷ density.

What depth of gravel do I need for a driveway?

For a standard residential driveway, a 4-inch compacted layer of gravel is typical. If you have heavy vehicles or poor soil, go to 6 inches. Remember to add 10% for compaction.

How much does a cubic yard of gravel weigh?

On average, a cubic yard of gravel weighs about 2,800 pounds (1.4 tons). This varies from 2,500 to 3,500 pounds depending on the type and moisture content. Multiply cubic yards by the density in lb/ft³ × 27 to get pounds.

Can I use this calculator for sand or soil?

Yes, the volume calculation is the same. Just change the density: sand is about 100 lb/ft³, topsoil about 80–100 lb/ft³. The weight output will be accurate for those materials as well.

Why is my calculated volume different from the supplier’s estimate?

Suppliers often use a different density or include compaction factors. They may also measure in loose cubic yards vs. compacted. Always clarify whether the price is for loose or compacted material, and ask for their density assumption.

What if my area is circular?

For a circle, use the formula: volume = π × (radius)² × depth. For example, a 10-foot diameter circle (radius 5 ft) with 3-inch depth is 3.1416 × 25 × 0.25 = 19.63 ft³. You can use this calculator by entering length = diameter and width = diameter, but that overestimates by about 21% – better to do the circular calculation separately.

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in l | Length | ft | 10 | 0
in w | Width | ft | 5 | 0
in d | Depth | in | 3 | 0
in den | Gravel density | lb/ft³ | 105 | 0
out vol_ft | Volume | ft³ | l * w * (d / 12) | 2
out vol_yd | Volume | yd³ | (l * w * (d / 12)) / 27 | 2
out tons | Weight | tons | (l * w * (d / 12) * den) / 2000 | 2