Fill Dirt Calculator with Compaction

Length of Area (Feet)

Width of Area (Feet)

Depth of Fill (Inches)

Compaction Factor (%)

Calculation Results

Base Volume: Cubic Yards

Total Dirt Needed (with Compaction): Cubic Yards

Estimated Weight: Tons

Note: Based on approximately 10-12 cubic yards per standard dump truck, you would need about truckloads.

function calculateFillDirt() { var length = parseFloat(document.getElementById("fd_length").value); var width = parseFloat(document.getElementById("fd_width").value); var depthInches = parseFloat(document.getElementById("fd_depth").value); var compaction = parseFloat(document.getElementById("fd_compaction").value); if (isNaN(length) || isNaN(width) || isNaN(depthInches) || isNaN(compaction)) { alert("Please enter valid numbers for all fields."); return; } // Convert depth to feet var depthFeet = depthInches / 12; // Calculate volume in cubic feet var cubicFeet = length * width * depthFeet; // Convert cubic feet to cubic yards (1 cubic yard = 27 cubic feet) var cubicYardsBase = cubicFeet / 27; // Apply compaction factor // Formula: Needed = Base Volume * (1 + (Compaction % / 100)) var cubicYardsTotal = cubicYardsBase * (1 + (compaction / 100)); // Estimate weight (Average loose dirt is ~2,200 lbs to 2,700 lbs per cubic yard) // Using an average of 1.25 tons per cubic yard var estimatedWeightTons = cubicYardsTotal * 1.25; // Estimate truckloads (Assume 10 yards per truck) var truckloads = Math.ceil(cubicYardsTotal / 10); document.getElementById("res_base_vol").innerText = cubicYardsBase.toFixed(2); document.getElementById("res_total_vol").innerText = cubicYardsTotal.toFixed(2); document.getElementById("res_weight").innerText = estimatedWeightTons.toFixed(2); document.getElementById("res_trucks").innerText = truckloads; document.getElementById("fd_results").style.display = "block"; }

Understanding Fill Dirt and the Compaction Factor

When planning a landscaping, construction, or grading project, one of the most common mistakes is underestimating the amount of fill dirt required. This usually happens because "loose" dirt occupies more space than "compacted" dirt. This calculator helps you account for the compaction factor to ensure you order enough material for a level, stable finished product.

Why Does Compaction Matter?

Fill dirt is naturally porous. When you excavate dirt or buy it from a supplier, it is "loose." Once you spread it on your site and drive over it with machinery or use a plate compactor, the air pockets are squeezed out. This causes the volume to shrink. If you calculate only the raw volume of your hole, you will find yourself short of dirt once you begin the tamping process.

Common Compaction Factors

Standard Landscaping: 10% to 15% compaction.
Foundation Backfill: 20% to 25% compaction.
Structural Road Base: Up to 30% compaction.

The Fill Dirt Formula

The basic formula used by professionals to calculate cubic yards is:

        ((Length in ft × Width in ft × (Depth in inches / 12)) / 27) × (1 + Compaction Percentage)
    

Practical Example

Imagine you have a low spot in your backyard that measures 30 feet long and 15 feet wide. You need to raise the level by 4 inches to prevent flooding. You plan to use a vibratory plate to ensure the soil doesn't settle later, so you use a 20% compaction factor.

Base Volume: 30′ × 15′ × 0.33′ (4 inches) = 148.5 cubic feet.
Convert to Yards: 148.5 / 27 = 5.5 cubic yards.
Add Compaction: 5.5 × 1.20 = 6.6 cubic yards.

In this scenario, ordering only 5.5 yards would leave you nearly a full yard short once the project is finished.

Weights and Truckloads

Soil weight varies based on moisture content and composition (clay vs. sand). On average, 1 cubic yard of dry fill dirt weighs about 2,200 to 2,600 pounds (roughly 1.1 to 1.3 tons). If the soil is wet, that weight can increase significantly. Most standard tandem dump trucks can carry between 10 and 14 cubic yards of material, while smaller single-axle trucks may carry only 5 to 7 yards.

Tips for Ordering Fill Dirt

Round Up: It is almost always better to have half a yard left over than to pay a second delivery fee for a small amount of missing dirt.
Check Soil Quality: "Clean fill" should be free of large rocks, roots, and trash.
Account for Settling: Even with manual compaction, natural settling will occur over the first few rain cycles.