Gravel Calculator: Estimate Tons & Cost

A gravel calculator estimates the amount of gravel you need for a project in cubic yards, cubic feet, and tons, based on the area’s length, width, and desired depth. You enter those three measurements (plus an optional price per ton), and it returns the volume and weight of gravel required, along with an estimated cost. This tool is essential for anyone planning a driveway, walkway, garden path, or drainage layer, because it prevents over-ordering (wasting money) and under-ordering (making extra trips to the supplier).

Formula

The calculator uses the standard volume formula for a rectangular prism, then converts to weight using the average density of gravel.

• Volume (cubic feet) = Length (ft) × Width (ft) × Depth (ft)
• Volume (cubic yards) = Volume (cubic feet) ÷ 27
• Weight (tons) = Volume (cubic feet) × Density (lb/ft³) ÷ 2000

Where:

• Length and Width are in feet (or convert from meters: 1 m = 3.281 ft).
• Depth is in inches (convert to feet by dividing by 12).
• Density is the weight per cubic foot of gravel. The calculator uses 1.4 tons per cubic yard, which equals about 103.7 lb/ft³ (1.66 metric tons/m³). This is a typical value for loose, dry gravel; actual density ranges from about 1.2 to 1.7 tons per cubic yard depending on gravel type and moisture.

Worked Example

Using the default values: length = 20 ft, width = 10 ft, depth = 4 in, price = $45/ton.

1. Convert depth to feet: 4 in ÷ 12 = 0.333 ft
2. Volume in cubic feet: 20 × 10 × 0.333 = 66.7 ft³
3. Volume in cubic yards: 66.7 ÷ 27 = 2.47 yd³
4. Weight in tons: 66.7 × 103.7 ÷ 2000 = 3.46 tons (or 2.47 yd³ × 1.4 = 3.46 tons)
5. Cost: 3.46 tons × $45/ton = $155.70

The calculator displays: 3.46 tons, 2.47 cu yd, and $155.70.

How to Use the Gravel Calculator

Using the tool is straightforward, but accuracy depends on your measurements. Follow these steps:

1. Measure the area – For a rectangular area, measure length and width in feet. For irregular shapes, break the area into rectangles, calculate each separately, and sum the results.
2. Decide on depth – Common depths: 2–3 inches for a walkway, 4–6 inches for a driveway, 6–8 inches for a base layer under pavers. Check with local suppliers or contractors for specific recommendations.
3. Enter your numbers – Input length, width, and depth (in inches). The calculator converts depth to feet automatically.
4. Optional price – Enter the cost per ton from your supplier to get a cost estimate.
5. Read the results – The first result, “Gravel needed� in tons, is what you’ll order. The volume in cubic yards is useful when comparing with suppliers who sell by volume.

Choosing the Right Gravel Type

Not all gravel is the same. The calculator assumes a typical density, but different materials have different weights. For example:

• Pea gravel – Rounded, small stones (3/8–1/2 inch). Density around 1.4 tons/yd³.
• Crushed stone – Angular pieces (e.g., #57 stone). Density around 1.5 tons/yd³.
• Bank gravel – Mixture of sand and gravel. Density can be up to 1.7 tons/yd³.
• Loose, dry gravel – Less dense, around 1.2 tons/yd³.

If you know the exact density of your material, you can adjust the result by multiplying the calculated tons by (actual density / 1.4). For instance, if using crushed stone at 1.5 tons/yd³, multiply the result by 1.5/1.4 = 1.07, adding about 7% to the tonnage.

Common Mistakes and How to Avoid Them

People often make these errors when estimating gravel:

• Mixing units – Entering length in meters but width in feet, or depth in inches without converting. Always use the same unit system. If your measurements are in metric, convert to feet first (1 m = 3.281 ft) or use a metric gravel calculator.
• Forgetting to convert depth – Depth is often measured in inches, but the formula requires feet. Dividing by 12 is essential.
• Rounding too early – Rounding the volume to 2.5 yd³ instead of 2.47 yd³ can change the tonnage by 0.04 tons, which is usually negligible, but for large projects it adds up.
• Ignoring compaction – Some gravel (like crushed stone) compacts when rolled, reducing volume by 10–20%. If you plan to compact, order 10–15% extra.
• Not accounting for depth variations – If your area isn’t perfectly flat, measure depth at several points and use the average.

Limitations of the Calculator

This calculator provides a good estimate, but real-world projects have variables:

• Density varies – The 1.4 tons/yd³ is an average. Moisture, stone size, and compaction change the weight. For critical projects, ask your supplier for the exact density.
• Shape irregularity – The formula assumes a perfect rectangle. For L-shaped or curved areas, break them into smaller rectangles or use a more advanced method.
• Waste and spillage – You’ll likely need 5–10% extra for spillage, settlement, or uneven ground. Add that to your order.
• Cost estimate – The cost is based solely on the price per ton. Delivery fees, taxes, and minimum order quantities are not included.

Frequently Asked Questions

How many tons of gravel do I need for a 20×10 foot area with 4 inches of gravel?

Using the calculator: 20 ft × 10 ft × (4/12) ft = 66.7 cubic feet. At 1.4 tons per cubic yard (about 103.7 lb/ft³), that’s 3.46 tons. So you’d order about 3.5 tons, or 4 tons to be safe.

What depth of gravel do I need for a driveway?

For a residential driveway, 4 to 6 inches of compacted gravel is typical. For a base layer under pavers, 6 inches is common. For a walkway, 2 to 3 inches is enough. Always check local building codes or consult a contractor for specific requirements.

How do I convert cubic yards to tons?

Multiply the volume in cubic yards by the density in tons per cubic yard. For example, 2.47 cubic yards × 1.4 tons/yd³ = 3.46 tons. If you have volume in cubic feet, divide by 27 to get cubic yards first.

Can I use this calculator for pea gravel?

Yes, but note that pea gravel density is similar (around 1.4 tons/yd³), so the estimate will be accurate. If your pea gravel is wet, it may weigh more; add 5% to the tonnage.

What if my area is circular or triangular?

For a circle, measure the diameter (in feet), divide by 2 to get the radius, then use the formula: π × radius² × depth. For a triangle, use 0.5 × base × height × depth. Then convert the volume to tons using the density (1.4 tons/yd³).

How much gravel do I need for a 100-foot driveway that is 10 feet wide?

Assuming 4 inches deep: 100 × 10 × (4/12) = 333.3 cubic feet = 12.35 cubic yards. At 1.4 tons/yd³, that’s 17.3 tons. Add 10% for compaction and waste, so order about 19 tons.

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in l | Length | ft | 20 | 0
in w | Width | ft | 10 | 0
in d | Depth | in | 4 | 0
in p | Price per ton | $ | 45 | 0
out tons | Gravel needed | tons | (l * w * (d / 12) * 1.4) / 2000 | 2
out cuyd | Volume | cu yd | (l * w * (d / 12)) / 27 | 2
out cost | Estimated cost | $ | tons * p | 2