Excavated Soil Calculator: Volume & Cost

This calculator works out the volume of soil excavated from a hole or trench, and estimates the amount of backfill needed. You enter the length, width, and depth (in feet or meters), and it returns the volume in cubic yards, cubic meters, and cubic feet, plus the approximate truckloads and backfill volume. The first result is the total excavated volume in cubic yards, the standard unit for earthwork in the US.

Formula

The basic formula for excavated volume is the same as for any rectangular prism:

V = L × W × D

• V = volume (cubic feet, cubic yards, or cubic meters)
• L = length of the excavation (ft or m)
• W = width of the excavation (ft or m)
• D = depth of the excavation (ft or m)

To convert cubic feet to cubic yards, divide by 27 (since 1 yard = 3 feet, so 1 cubic yard = 3³ = 27 cubic feet). To convert cubic feet to cubic meters, multiply by 0.0283168 (since 1 ft = 0.3048 m, so 1 ft³ = 0.3048³ ≈ 0.0283168 m³).

Worked Example

Using the default values from the calculator above: length = 10 ft, width = 5 ft, depth = 3 ft.

1. Calculate volume in cubic feet: 10 × 5 × 3 = 150 ft³
2. Convert to cubic yards: 150 ÷ 27 = 5.56 cu yd
3. Convert to cubic meters: 150 × 0.0283168 = 4.25 m³
4. Estimate backfill (assuming 90% of the excavated soil is used for backfill after compaction): 5.56 × 0.9 = 5.00 cu yd

The calculator shows 5.56 cu yd for the excavated volume, matching the step-by-step result.

When to Use This Calculator

You need this calculator any time you plan to dig for a foundation, utility trench, swimming pool, garden pond, or septic system. It helps you:

• Estimate how much soil will be removed and need hauling away.
• Order the right amount of fill dirt or gravel for backfill.
• Compare quotes from excavation contractors who charge by the cubic yard.
• Plan for disposal costs, which are usually per cubic yard.

For irregular shapes (like sloped trenches or round footings), the formula still works if you use average dimensions. For a circle, use the formula for a cylinder: V = π × r² × D, then convert to cubic yards by dividing by 27.

How to Read the Results

The primary result is the excavated volume in cubic yards. This is the number you give to a trucking company or use to estimate the number of truckloads. A standard dump truck holds about 10–14 cubic yards of loose soil, so divide your total by 12 to get a rough truckload count. For example, 5.56 cu yd means you need less than one full truckload.

The backfill estimate assumes you will reuse the excavated soil and that it compacts to about 90% of its original volume. In reality, soil expands when dug (called “bulking�) and then settles when compacted. The 90% factor is a common rule of thumb, but it varies with soil type: sandy soil compacts more, clay less.

Common Mistakes and Misconceptions

The most frequent error is mixing units. If you measure length in feet and width in meters, the result will be wrong. Always convert to the same unit before multiplying. Another mistake is forgetting that the volume of a hole is not the same as the volume of soil removed. When you dig, the soil “bulks� or expands by 10–30% depending on the type. This means the truckload volume will be higher than the hole volume. Conversely, when you backfill, the soil compacts, so you need less than the hole volume.

A common misconception is that a cubic yard of soil weighs the same everywhere. In reality, topsoil weighs about 2,000–2,700 lbs per cubic yard, while wet clay can exceed 3,000 lbs. If you are paying for disposal by weight, use a conversion factor of about 1.5 tons per cubic yard for mixed soil.

Choosing the Right Volume for Your Project

For small projects like a garden bed, you can measure in cubic feet. For large excavations, use cubic yards. Here is a quick guide:

• Post holes: Usually less than 1 cu yd total.
• Trench for utility line: 1–5 cu yd for a typical residential run.
• Foundation for a small shed: 5–20 cu yd.
• Swimming pool: 50–200 cu yd.

If your project has sloped sides (like a trench with a batter), the actual volume is slightly larger than the simple L×W×D calculation. For a trapezoidal cross-section, use the average width: (top width + bottom width) / 2.

Safety and Accuracy Notes

Excavation is dangerous. Always call 811 before digging to locate underground utilities. For trenches deeper than 4 feet, OSHA requires a protective system (shoring, sloping, or shielding). Never enter an unprotected trench. The calculator gives you the volume, but it does not account for soil stability, groundwater, or the need for shoring. Check local building codes for minimum depth requirements for footings (often 12 inches below frost line).

For accuracy, measure depth at several points and use the average. If the ground is sloped, measure from the lowest point to avoid underestimating. Always add 10–15% to your order for waste and compaction losses.

Alternatives and Related Calculations

If you are not excavating a rectangular prism, use these variations:

• Circular hole: V = Ï€ × r² × D (r = radius).
• Sloped trench: V = L × D × (W_top + W_bottom) / 2.
• Irregular shape: Break it into rectangles and add the volumes.

For backfill, you might need to order gravel or sand. These materials are sold by the cubic yard, but they have different compaction factors. Gravel compacts less than soil, so you might use a factor of 0.85 instead of 0.9. Always confirm with your supplier.

Frequently Asked Questions

How many cubic yards are in a ton of soil?
It depends on the soil type and moisture. Dry topsoil is about 1.3 tons per cubic yard, while wet clay can be 1.8 tons per cubic yard. To convert tons to cubic yards, divide the weight by the density (in tons per cubic yard).

What is the bulking factor for excavated soil?
Bulking factor is the percentage increase in volume when soil is dug up. It ranges from about 10% for sand to 30% for clay. Multiply the hole volume by (1 + bulking factor) to get the loose volume you need to haul away.

How much does it cost to remove excavated soil?
Costs vary widely by location and disposal fees. As a rough guide, hauling and disposal might run $10–$30 per cubic yard, but that is not a guarantee. Get quotes from local contractors.

Can I use this calculator for a sloped excavation?
Yes, but you need to adjust the depth. For a sloped bottom, use the average depth. For sloped sides, use the average width. The formula still gives a good estimate.

What is the difference between bank cubic yards and loose cubic yards?
Bank cubic yards (BCY) is the volume of soil in its natural, undisturbed state. Loose cubic yards (LCY) is the volume after digging, which is larger due to bulking. This calculator gives BCY. To get LCY, multiply by the bulking factor.

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in l | Length | ft | 10 | 0
in w | Width | ft | 5 | 0
in d | Depth | ft | 3 | 0
out vol_cy | Excavated volume | cu yd | (l * w * d) / 27 | 2
out vol_cf | Volume | cu ft | l * w * d | 1
out vol_cm | Volume | cu m | l * w * d * 0.0283168 | 2
out backfill | Backfill (90% compaction) | cu yd | ((l * w * d) / 27) * 0.9 | 2