How Much Extra Soil Should I Order?

The short answer

Order 10–20% more soil than your calculated volume — that's the industry buffer rule, and it exists because a “loose yard” in the truck is not the same thing as a compacted yard in the ground. Use 15% as your default for topsoil and fill dirt, 10% for sand, 20% for decomposed granite and deep compacted fills, and near-zero for clean gravel (it barely settles). The second delivery fee you avoid is almost always worth more than the extra yard costs.

The fluff factor, in plain English

Bulk soil is sold by the loose cubic yard — the volume it occupies fluffed up in the truck bed, full of air from screening, loading, and the ride over. Your project needs compacted cubic yards — the volume the same soil occupies after gravity, rain, and watering collapse the air pockets and the particles settle into each other. The difference between the two is the fluff factor, and it's why ordering your exact calculated volume always leaves you short.

Think of it like a bag of chips: the bag's volume and the chips' volume are not the same thing. A yard of topsoil that fills a 6-inch-deep bed on delivery day settles to roughly 5 inches after a few waterings — the soil didn't go anywhere, it just stopped being 20% air. Mechanical compaction (a plate compactor, roller, or just heavy equipment driving over it) speeds up the same process deliberately.

Settlement rates by material

Different materials carry different amounts of air and pack down differently. These are industry rules of thumb, not lab measurements — treat them as planning ranges:

The decomposed granite and crusher run rows deserve emphasis: those buffers aren't really “settlement” — they're compaction loss you plan for. A 4-inch compacted DG path needs about 5 inches of loose material to get there. Order the loose volume, not the finished depth.

Order buffers by project type

Material is half the story; what you're building with it is the other half. A raised bed and a pool fill both use “dirt,” but they settle for different reasons and want different buffers:

Worked examples

Raised bed, 8 × 4 ft, 1 ft deep. Volume: 32 cu ft = 1.19 cubic yards. Topsoil at a 15% buffer: 1.19 × 1.15 = 1.37 → order 1.5 yards. That extra third of a yard is what keeps the bed full after a month of watering.

Grade raise, 20 × 20 ft, 4 inches deep. Volume: 133 cu ft = 4.94 cubic yards. Fill dirt at 15%: 4.94 × 1.15 = 5.68 → order 6 yards (about 6.6 tons). Spread and compact it in two lifts rather than dumping all 6 inches at once.

Topsoil layer, 2 inches over 500 sq ft. Volume: 83 cu ft = 3.09 cubic yards. At 15%: 3.09 × 1.15 = 3.55 → order 4 yards (about 4.8 tons). Rounding up to the full yard is cheaper than a top-off delivery.

Paver base, 200 sq ft, 4 inches compacted. Compacted volume: 66.7 cu ft = 2.47 cubic yards. Crusher run needs ~17% extra loose to compact to that depth: 2.47 × 1.17 = 2.89 → order 3 yards. Compact in 2-inch lifts with a plate compactor, watering lightly between passes.

For the base calculation on any of these, our dirt calculator, fill dirt calculator, and topsoil calculator handle the volume math — then apply the buffer from the tables above.

Rain settling vs mechanical compaction

Both collapse the air out of soil, but they are not interchangeable. Rain settles soil unevenly — low spots collect water and settle more, high spots less, which is how a freshly graded yard develops dips after the first storm. Rain is fine for the final settle of a garden bed, but it's a terrible way to compact structural fill. Mechanical compaction — a plate compactor for granular soils, a sheepsfoot or smooth roller for clay-heavy fill — densifies soil uniformly and immediately, in controlled lifts. The rule: compact anything that will carry weight (paver bases, slab subgrade, backfill against foundations) in 6 to 12-inch lifts; let rain and time finish garden beds and non-structural fills. Watering a lift lightly before compacting helps particles slide into place — damp, not muddy.

Leftover soil vs the top-off order

The buffer rule means you'll sometimes have soil left over — that's the design working, not a mistake. Keep the leftover on a tarp, not on the lawn (it'll kill the grass underneath in a week). After the first good rain, walk the project: the low spots that appear are exactly what the leftover is for. Genuinely excess topsoil is easy to move — neighbors, community garden groups, and local listings absorb it fast.

The scenario to avoid is the top-off order: you ordered exact, the project settled short, and now you need one more yard. Most suppliers charge a minimum delivery fee, so a single-yard top-off often costs nearly as much as a full small load. That fee is the entire economic argument for the buffer rule — a yard of extra dirt on day one is the cheapest dirt you'll ever buy.

Yards to tons for ordering

Bulk soil is often priced by the yard but hauled by weight — and truck capacity is a weight limit. Convert with the material's density:

For delivery planning: a pickup truck carries roughly 2–3 yards, a single-axle dump truck 8–10 yards, and a tandem-axle dump 16–20 yards — weight permitting. Wet soil weighs noticeably more than dry, so a load ordered after heavy rain can push a truck's limit sooner than the yardage suggests.

Common mistakes

Ordering exact calculated yards. The fluff factor guarantees a shortfall — the buffer isn't optional padding, it's the real quantity. Compacting only at the end. Deep fill compacted once on top hides soft layers underneath; work in lifts. Treating bagged and bulk yards as equal. Bagged soil is denser than bulk loose yards — don't mix the two unit systems in one estimate. Forgetting the delivery minimum. Price the job including delivery fees before deciding the buffer is “waste.” Compacting garden beds like a paver base. Plant roots need loose soil — settle beds with water, not a plate compactor.