The Formula
Everything comes down to one calculation — volume in cubic yards, with a compaction buffer:
The 1.15 factor adds 15% for compaction settlement after placement.
Step-by-Step Calculation
Follow these five steps for any fill dirt project:
Measure the area
Measure length and width of the area to be filled in feet. For irregular shapes, break the area into rectangles and calculate each one separately, then add the totals.
Determine required depth
Measure how many inches of fill you need — the difference between current grade and target grade. Convert to feet by dividing by 12. (6 inches = 0.5 ft; 12 inches = 1.0 ft; 18 inches = 1.5 ft.)
Calculate cubic feet
Multiply: Area (sq ft) × Depth (ft) = cubic feet. This is the raw volume before any unit conversion.
Convert to cubic yards
Divide cubic feet by 27. There are 27 cubic feet in one cubic yard — that's a 3×3×3-foot cube. Fill dirt is sold and delivered by the cubic yard.
Add 15% for compaction
Multiply your cubic yard number by 1.15. Fill dirt compacts after placement — it settles 10 to 15% under its own weight and any mechanical compaction. Without this buffer, you will run short.
Reference Table: Common Projects
| Project | Area | Depth | Approx. Cubic Yards |
|---|---|---|---|
| Raising a 20×30 area by 6" | 600 sq ft | 0.5 ft | ~13 yards |
| Filling a 10×10 low spot, 1 ft deep | 100 sq ft | 1 ft | ~4 yards |
| Backfilling a foundation (100 LF, 2 ft wide, 4 ft deep) | 200 sq ft | 4 ft | ~34 yards |
| Raising a 50×50 area by 12" | 2,500 sq ft | 1 ft | ~107 yards |
Converting Cubic Yards to Tons
Fill dirt is sometimes quoted in tons rather than cubic yards. The conversion depends on moisture content and soil type, but fill dirt typically runs 1.3 to 1.4 tons per cubic yard.
Multiply your cubic yard number by 1.35 to get a working ton estimate. Example: 20 cubic yards × 1.35 = 27 tons.
Keep in mind that trucks are loaded by volume in the field, so the cubic yard number is the more useful measurement for ordering and delivery planning.
Truck Sizes and Delivery Minimums
A quad-axle dump truck carries approximately 14 to 16 cubic yards of fill dirt per load. That's the standard delivery vehicle for most residential and commercial fill orders.
J1S also runs smaller trucks for quantities that don't warrant a full quad-axle load. If your calculation comes out to 5 or 6 yards, you don't need to pay for a full truck — call and we'll match the right equipment to your quantity.
For large projects — foundation backfill, site raising, pond construction — we'll coordinate the number of loads and truck cycles based on your total volume and timeline.
The Compaction Factor Explained
The 15% buffer in the formula accounts for what happens when fill is placed and compacted. Loose fill dirt, when mechanically compacted in 6-inch lifts, settles into a denser state. A yard of loose fill becomes roughly 0.85 to 0.90 yards of compacted fill. Depending on the soil type and moisture, settlement can run as high as 20%.
Under-ordering and needing a second delivery is typically more expensive than the material itself — you pay another truck trip, mobilization time, and often schedule delay. The 15% buffer is inexpensive insurance.
Not Sure What Material You Need?
If you're still deciding whether your project needs fill dirt, topsoil, or both, read our guide on the difference between the two — it covers the layering principle and the most common ordering mistakes:
Fill Dirt vs. Topsoil: What's the Difference and Which Do You Need? →