Excavation Calculator per Cubic Yard

This excavation calculator tells you the volume of dirt to be removed in cubic yards, along with the estimated weight and truckloads required. You enter the length, width, and depth of the excavation area, and the calculator returns the cubic yards and related figures. Use it to plan a project, order fill or disposal, and estimate hauling needs.

Formula

The core formula for excavation volume in cubic yards is:

Volume (yd³) = (Length × Width × Depth) / 27

Where:

• Length – the longest horizontal dimension of the excavation area, in feet.
• Width – the shorter horizontal dimension, in feet.
• Depth – how deep you dig, in feet.
• 27 – the number of cubic feet in one cubic yard (3 ft × 3 ft × 3 ft).

If you measure in inches, convert depth to feet first (divide by 12). If you measure in meters, convert to feet (1 m = 3.28084 ft) or use a metric version of the formula.

Worked Example

Using the default values: Length = 20 ft, Width = 10 ft, Depth = 2 ft.

Step 1: Calculate cubic feet: 20 × 10 × 2 = 400 ft³.

Step 2: Convert to cubic yards: 400 ÷ 27 = 14.81 yd³.

Step 3: Estimated weight (assuming 1.4 tons per cubic yard of common soil): 14.81 × 1.4 = 20.74 tons.

Step 4: Truckloads (10 yd³ per truck): 14.81 ÷ 10 = 1.48, so about 2 loads.

The calculator shows the same: 14.81 cubic yards, 20.74 tons, and 1.5 loads (rounded to one decimal).

Why Cubic Yards Matter in Excavation

Excavation contractors quote prices per cubic yard because volume is the most consistent way to measure work. A cubic yard is 27 cubic feet – imagine a box 3 feet long, 3 feet wide, and 3 feet high. That volume of soil weighs roughly 1.4 tons (about 2,800 lb) for moist topsoil, but can range from 1.2 tons for dry sandy soil to over 2 tons for wet clay. Knowing the volume helps you:

• Compare quotes from different contractors fairly.
• Order the right amount of fill dirt or gravel for backfill.
• Estimate disposal costs if you must haul the spoil away.
• Plan for equipment size – a small mini-excavator can move about 50–100 yd³ per day, while a large excavator can move 500+ yd³.

How to Measure Your Excavation Site

Accurate measurements are essential for a reliable calculation. Follow these steps:

1. Measure length and width at the top of the excavation, in feet. For irregular shapes, break the area into rectangles and calculate each separately, then add the volumes.
2. Measure depth from the ground surface to the final bottom. For sloped sides, use the average depth.
3. Account for slopes – if the sides are angled (common for safety), the actual volume is less than a straight-walled calculation. Use the average of top and bottom dimensions for a more accurate estimate.
4. Add a buffer of 10–15% for uneven ground, compaction, and spillage during digging.

For a trench, the formula is the same: length × width × depth. For a circular footing, use π × radius² × depth, then divide by 27.

Common Mistakes and How to Avoid Them

Several errors can throw off your excavation estimate:

• Mixing units – Always convert inches to feet (divide by 12) before multiplying. A depth of 6 inches is 0.5 ft, not 6 ft.
• Forgetting the /27 – Many people calculate cubic feet and mistakenly think it’s cubic yards. One cubic yard is much larger than a cubic foot.
• Ignoring soil type – Weight varies widely. Sandy dry soil may be 1.2 tons/yd³, while wet clay can be 1.8 tons/yd³ or more. Use the actual weight for your soil type when estimating hauling costs.
• Not accounting for compaction – When you dig, the soil expands (becomes “fluffyâ€�) and may increase in volume by 20–30%. When you backfill, it compacts and settles, so you may need extra fill.
• Rounding too early – Round only the final answer, not intermediate steps, to avoid significant error.

How to Choose the Right Excavation Method

The calculator gives you volume, but the method depends on the project size and access:

• Hand digging – Suitable for small volumes (under 5 yd³) where equipment can’t reach. Labor-intensive but low cost for tiny projects.
• Mini-excavator – Best for 5–200 yd³ in tight spaces. Can load into a small dump truck.
• Backhoe – Common for trenches and foundations up to about 500 yd³.
• Large excavator – For major earthworks over 500 yd³, often paired with dump trucks for hauling.

For most residential projects (swimming pools, footings, small basements), a mini-excavator or backhoe is typical. The volume you calculated helps you decide if a truck can handle the spoil in one trip or if you need multiple loads.

Cost Considerations Beyond Volume

While the calculator provides the cubic yardage, actual excavation costs depend on more than volume:

• Labor rates – Typically quoted per hour or per cubic yard.
• Equipment rental or operator fees – Often a minimum charge, like 4 hours.
• Disposal fees – If you haul dirt away, the dump site may charge per ton or per load.
• Access and site conditions – Tight spaces, rocky soil, or underground utilities increase time and cost.
• Permits – Some areas require permits for large excavations, adding fees.

Use the volume to get a rough idea, but always get a detailed quote from a contractor who can assess site-specific factors.

Safety and Accuracy Tips

Excavation is dangerous work. Always follow these safety guidelines:

• Call before you dig – In many regions, you must contact a utility locator service to mark underground lines before any digging.
• Slope or shore trenches – Trenches deeper than 4 feet require sloping, benching, or shoring to prevent collapse.
• Keep equipment away from edges – The weight of an excavator can cause cave-ins.
• Check for groundwater – Water in the excavation can destabilize walls and require pumping.
• Use the calculator for planning, not as a substitute for engineering – For large or deep excavations, consult a professional engineer.

Frequently Asked Questions

How many cubic yards can a dump truck hold?

A standard dump truck holds 10–14 cubic yards of loose material. A smaller pickup truck with a bed might hold 2–3 cubic yards. The calculator’s default truck size is 10 yd³, but you can adjust for your truck.

How much does a cubic yard of dirt weigh?

It depends on moisture and composition. Dry topsoil weighs about 1.2 tons per cubic yard, moist soil about 1.4 tons, and wet clay can reach 1.8 tons. The calculator uses 1.4 tons as a default, but you can adjust the weight in your own calculations.

Do I need to add extra volume for the soil that expands when dug?

Yes. When soil is excavated, it “fluffs upâ€� and can increase in volume by 20–30% (called bulking). If you’re hauling away the spoil, you may need a larger truck or an extra load. If you’re backfilling, the soil will compact, so you may need to add 10–15% more fill.

What if my excavation isn’t a perfect rectangle?

Break the area into rectangles, calculate each volume, and add them together. For irregular shapes, you can also use the average of the top and bottom dimensions to account for sloped sides. For a circular hole, use the formula for a cylinder: π × radius² × depth.

Can I use this calculator for fill dirt or gravel?

Yes, the volume calculation is the same for any material. Just change the weight per cubic yard if you need weight estimates. Gravel typically weighs about 1.4 tons per cubic yard, similar to soil, but check the specific material.

Why is the result in cubic yards and not cubic feet?

Because excavation contractors, dump trucks, and material suppliers all use cubic yards as the standard unit for earthwork. It’s a larger unit that keeps numbers manageable – a small foundation might be 50 yd³, which would be 1,350 ft³.

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in l | Length | ft | 20 | 0
in w | Width | ft | 10 | 0
in d | Depth | ft | 2 | 0
out cy | Cubic yards | yd³ | (l * w * d) / 27 | 2
out weight | Estimated weight | tons | (l * w * d) * 1.4 / 2000 | 2
out loads | Truckloads (10 yd³ truck) | loads | ((l * w * d) / 27) / 10 | 1