Quick Verdict
To figure out how much fill dirt you need, calculate the volume (length times width times depth) in cubic yards, then add a shrink factor because dirt compacts down when you place and compress it. The catch most people miss: ordering by the loose-volume size of the hole leaves you short, because compacted fill takes more material than the empty space it fills. Structural fill needs even more allowance. For an accurate number on a real project, a takeoff from the grading plan beats any rule of thumb. Order a little extra rather than stopping work for a second haul.
The Basic Volume Calculation
Start with the simple math. Fill volume in cubic yards is:
- Length (ft) x Width (ft) x Depth (ft), divided by 27 = cubic yards. (There are 27 cubic feet in a cubic yard.)
So a pad 30 ft by 40 ft that needs 1 ft of fill is 30 x 40 x 1 = 1,200 cubic feet, divided by 27 = about 44.4 cubic yards before any adjustments. Use the average depth if the depth varies across the area. This is the starting point, not the final order. The broader pad-prep picture is in our site preparation guide for Oregon.
Loose vs. Compacted Yards (The Shrink Factor)
Here is the part that trips people up. Dirt is sold and hauled "loose," but on your site it gets compacted. Compaction squeezes the air out, so the material shrinks.
- Loose yards are how it sits in the truck and the pile.
- Compacted yards are how much volume it fills after it is placed and compacted.
- Shrink factor is the difference. You generally have to order MORE loose material than the compacted volume you are filling.
The exact shrink depends on the material and how it is compacted, so add a reasonable allowance rather than ordering exactly to the void.
Why Structural Fill Needs Even More
Not all fill is equal. Casual fill just takes up space, but structural (engineered) fill is placed in controlled lifts and compacted hard to carry load. That heavy compaction increases the shrink, so structural fill needs an even larger allowance over the raw void volume. The properties and use of structural fill are covered in engineered fill explained. Using the wrong material, or under-ordering it, undermines whatever you build on top.
A Quick Reference for Common Pads
These are rough planning numbers before shrink, using the area times depth method.
| Pad Size | Depth | Approx. Cubic Yards (before shrink) |
|---|---|---|
| 20 x 20 ft | 6 in | About 7.4 cu yd |
| 30 x 40 ft | 1 ft | About 44.4 cu yd |
| 40 x 60 ft | 1 ft | About 88.9 cu yd |
| 50 x 50 ft | 2 ft | About 185 cu yd |
Ordering by the Yard or Ton in Oregon
In Oregon you typically order fill dirt, crushed rock, or sand from a local pit by the cubic yard or by the ton (weight). A few practical notes:
- Truck counts. Dividing your total yards by the truck capacity tells you how many loads, which drives haul cost.
- Clay shrink/swell. Willamette Valley clay changes volume with moisture, so factor that in.
- Material choice. Crushed rock, sand, and screened fill each behave differently when compacted.
Whether to bring fill in or move material around on site is its own decision, covered in import vs export dirt on a site.
Matching the Material to the Job
Volume is only half the order. The other half is picking the right material, because the wrong one fails no matter how many yards you bring in. Around the Willamette Valley you are usually choosing among a few common options:
- Common fill / pit-run dirt. Cheapest, fine for filling a low spot or raising a non-structural area, but it is not a base for a building or driveway.
- Screened or select fill. Cleaner and more consistent, easier to compact, a step up when something will sit on top.
- Crushed rock (3/4-inch minus is the workhorse). Drains well, compacts hard, and is the go-to base under driveways, slabs, and shed pads, which matters in our rainy climate.
- Sand. Sometimes used for pipe bedding or drainage layers, not as general structural fill.
The reason this matters for your estimate: clay-heavy valley soil holds water and shrinks and swells with the seasons, so a pad built on raw clay fill can heave and settle. That is why many Oregon pads end up on crushed rock rather than dirt, even though rock costs more per yard. You are paying for a base that holds through the wet months.
Order Smart, Not Just Enough
Getting the number right is step one. Ordering it well is step two, and a few habits keep the job from stalling.
- Round up, not down. It is cheaper to have a little extra than to halt a crew waiting on a second truck.
- Confirm what a "yard" means. Pits sell loose yards; your hole is a compacted volume. Always order to the loose number plus shrink.
- Check access before the truck shows up. A standard dump truck needs room to turn and dump. Tight or soft sites may need a smaller truck or more trips, which changes the cost.
- Time deliveries for the dry window. Hauling and placing fill is far easier in the roughly May-to-October dry season, when the ground is firm and material is not soaking up rain.
- Have a spot ready for the pile. Know where the material lands so you are not double-handling it across the site.
A little planning here is the difference between a clean one-day placement and a muddy, multi-trip headache.
What Getting It Wrong Costs
Under-ordering is the expensive mistake.
Industry Baseline Range: fill dirt delivered runs $20 - $75+ per cu yd and crushed gravel $45 - $110+ per cu yd, with dump-truck loads of $250 - $750+ per load, so a second haul to make up a shortfall adds mobilization and delivery on top.
These are industry baseline ranges for planning only -- actual pricing depends on site conditions, soil, access, depth, haul-off, and current market conditions. Get a site-specific quote.
Current Market Reality
Real costs often run 2-3x baseline when the site needs structural fill instead of common fill, when a long haul from the pit adds delivery, or when an under-estimate forces a repeat trip and re-mobilization. A takeoff from the grading plan is the cheapest insurance against ordering wrong.
The Bottom Line
Estimating fill dirt is area times depth in cubic yards, plus a shrink factor so you order enough, with structural fill needing the biggest allowance. Use the quick math to plan, but get a real takeoff for the actual job, and order a little extra to avoid a costly second haul. To get an accurate volume for your pad, request a free estimate and explore our excavation services.