How Much Fill Dirt Do I Need?

The short answer

Yards = (length × width × depth in feet) / 27, then order 10–20% extra because loose fill settles as it compacts. A 6×6 hole that's 2 feet deep is (6 × 6 × 2) / 27 = 2.67 cubic yards — order 3 to 3.5. Tons = yards × 1.1 (fill dirt runs about 2,200 lbs per yard). The extra percentage is the part everyone skips: the void you measure is compacted volume, but dirt arrives loose and full of air.

Worked examples across scenarios

Check the low-spot math: 20 × 30 = 600 sq ft × 0.5 ft = 300 cu ft / 27 = 11.11 yards; × 1.1 = 12.22 tons. For uneven areas, measure depth in several spots and average — a low spot that's 9 inches in the middle and 3 at the edges is a 6-inch average. And the pool row uses the higher end of the compaction range (15–25%) because deep fills compress more; demolished wall rubble displaces some void but doesn't compact like clean fill.

The compaction rule (order +10–20% extra)

Here's why the extra matters. Dirt delivered loose is full of air voids — up to a third of its volume can be nothing. Dump it in a hole and it settles 15–30% over the coming months, leaving a shallow crater where you thought you were done. Ordering 10–20% over the measured void is the floor, not the ceiling. The real fix is mechanical: compact the fill in 6–12 inch lifts with a plate compactor (small jobs) or tracked equipment / a jumping jack (deep fills). A lift compacted before the next one goes down can't collapse later. Clay-heavy fill compresses more than sandy fill, and deep fills need the higher end of the overage range. If you compact properly in lifts, the surface stays where you put it.

Filling an old swimming pool

A 16×32 pool averaging 5 feet deep holds about 95 cubic yards of void (16 × 32 × 5 / 27 = 94.8) — before the walls, the deck demo debris, and compaction. The working number most contractors use: order 110–120 yards. At 1.1 tons per yard that's 121–132 tons, roughly 6–7 tri-axle truckloads (about 18 yards per load), so schedule delivery across days and confirm site access for repeated heavy trucks. Two cost contexts frame the decision: a partial fill (punching drainage holes in the shell, breaking the top 18–24 inches of walls down, engineered compacted fill) typically runs $3–7k, while full removal (pool shell excavated and hauled out) runs $9–19k. Partial fills are cheaper but can complicate future building on the spot — disclose it on any sale. And the permit note: most jurisdictions require a permit and inspection for pool decommissioning, often with compaction records. Check before the first truck arrives.

Fill dirt, then topsoil: the layering order

For any fill that ends in lawn, the layering is: fill dirt for the bulk, topsoil for the top 4–6 inches. Fill dirt is subsoil — cheap, stable, no organic matter. It's exactly what you want under a lawn and exactly what plants don't want around their roots. Using topsoil for deep fill is a double loss: it costs more per yard and settles more as its organic content breaks down. Rough in the grade with fill dirt, compact it, then cap with 4–6 inches of screened topsoil for seed or sod. Our topsoil vs fill dirt guide covers the full comparison if you're deciding between the two materials.

How many truckloads is that?

A tri-axle dump truck hauls roughly 18–20 yards of fill dirt per load (about 20–22 tons at 1.1 tons/yard). So the 13-yard low-spot fill is one load; the 17-yard leveling job is one load, maybe two if the truck is a smaller single-axle; and the 110–120 yard pool fill is6–7 full loads. That's the part to plan for on big fills: repeated heavy trucks need solid ground access, and the supplier may want the order split across days. For small holes under 3 yards, many suppliers sell by the half yard with pickup in a trailer — a 2.67-yard hole is about what two full pickup beds carry, but check your truck's payload first (3 yards of fill dirt weighs over 3 tons).

Cost context

Bulk fill dirt typically runs $10–30 per cubic yard, with delivery fees of $50–150 depending on distance and load size. That puts a 3-yard hole fill at roughly $100–200 delivered, and a 13-yard low-spot job at $200–500. The pool fill is a different animal: 110–120 yards at $15–25/yard is $1,650–3,000 in material alone before the demolition and engineered compaction work — which is why partial fills land in the $3–7k range and full removals reach $9–19k. “Free fill dirt” from construction sites can work for non-structural fills, but verify what's in it before you accept a load.

Common mistakes

Ordering the exact void volume. The #1 under-ordering mistake — the surface sinks within a year. Filling deep holes in one dump. Loose fill bridges over voids; compact in lifts. Burying organic debris. Logs, brush, and demolition wood decompose and collapse — a guaranteed future sinkhole. Haul organics out. Topsoil for deep fill. Expensive, settles more, and buries your good soil where roots can't reach it. Skipping the permit on pool fills. Inspectors can order a completed fill reopened. Grading toward the house. Level the yard, but keep a gentle fall away from foundations — a flat yard with a wet basement is a bad trade.