How Much Dirt Do I Need to Regrade or Level My Yard?

The short answer

Regrading a slope is wedge math: cubic yards = (½ × run in ft × drop in ft × length in ft) / 27. A 10-foot run with 6 inches of fall along a 40-foot house is (½ × 10 × 0.5 × 40) / 27 = 3.7 cubic yards — order 4.5 with the 15–20% compaction allowance. Lawn leveling is different math: 1,000 sq ft at ½ inch deep is 1.54 yards. Important: this guide covers slopes and leveling; if you're filling a pit, pool, or hole, that's void math — see our fill dirt for holes guide instead.

Wedge math for the drainage slope

The standard foundation drainage grade is 6 inches of fall over the first 10 feet away from the house (about a 5% grade). Picture the wedge: zero drop at the far edge, full 6-inch drop at the house — the average depth is half the drop, which is why the formula uses ½. Convert the 6-inch drop to 0.5 feet, multiply by the 10-foot run and the length of the slope (your house width), halve it, and divide by 27.

Worked example: 10-ft run × 0.5-ft drop × 40-ft house width → ½ × 10 × 0.5 × 40 = 100 cu ft / 27 = 3.70 cubic yards. Add 20% for compaction → 4.44 → order 4.5 yards. At fill dirt's 1.1 tons per yard, that's about 4.9 tons of material before the topsoil cap (more on layering below).

Check the 50-foot row: ½ × 10 × 0.5 × 50 = 125 cu ft / 27 = 4.63 yards; +20% = 5.56, so order 5.5–6. For a gentler grade over a longer run — 15 feet with the same 6-inch drop — the wedge grows: ½ × 15 × 0.5 × 40 = 150 cu ft / 27 = 5.56 yards, order 7 with compaction allowance. Longer runs spread the fall more gracefully and are easier to mow, at the cost of more material.

Lawn leveling: thin layers, not one pour

Leveling a bumpy lawn uses different math from the wedge: uniform depth over the whole area. The rule is ¼ to ½ inch per pass — never bury the grass deeper than half an inch, or you'll smother it. Deep spots get repeated passes weeks apart, each one after the grass grows through. The formula is the flat one: (area × depth in ft) / 27.

Verify the 1,000 sq ft row at ½ inch: 1,000 × (0.5 / 12) = 41.67 cu ft / 27 = 1.54 yards — about 1.85 tons of topsoil at 1.2 tons per yard. Note the 5,000 sq ft @ ½ inch row: 7.72 yards = 9.26 tons — that's a full dump-truck delivery, not a pickup-bed project. Scale creep is the surprise of lawn leveling: what sounds like “a thin layer” is a lot of tons on a big lawn.

Fill dirt below, topsoil on top

For any regrade that ends in grass, the layering order is fixed: fill dirt for the bulk, 4–6 inches of topsoil on top. Fill dirt is cheap, stable subsoil — it holds the grade without settling much. Topsoil is where seed or sod lives. Using topsoil for the whole wedge costs more per yard and settles more, since its organic content breaks down over time. Our topsoil vs fill dirt guide compares the two materials in detail.

Worked layering on the 40-foot example: the wedge itself is 3.7 yards — order 4.5 yards of fill dirt. The topsoil cap covers the wedge's top surface: the sloped surface is about 400 sq ft (10.01-ft slope length × 40 ft wide). A 4-inch cap: 400 × (4 / 12) = 133.3 cu ft / 27 = 4.94 yards — order 5 yards of topsoil. Notice the cap is bigger than the wedge: on a shallow regrade, the finish layer often dominates the order. Budget both materials separately.

The 15–20% compaction add-on

Dirt arrives loose — up to a third of a load can be air. Dumped into a wedge without compaction, it settles 15–30% over the first year, and a wedge that settles leaves a swale that ponds water exactly where the old low spot was. Order 15–20% over the wedge math, then compact in 6–12 inch lifts with a plate compactor (small jobs) or tracked equipment (big ones). Compacted in lifts, the grade stays put. Sandy fill compacts less and drains faster; clay-heavy fill holds grade well but needs the higher end of the overage.

Measure the drop before you order

The wedge math only works with real numbers. Stretch a string line tight between two stakes — one at the foundation, one 10 feet out — level it with a line level, and measure the gap between the string and the ground at the house stake: that's your current drop. Repeat every 10 feet along the foundation; a yard that's 6 inches low in one spot and flat in the next needs spot wedges, not one average number. If the ground actually slopes toward the house anywhere, the wedge there is deeper — measure those spots separately.

When to call a grader

DIY regrading tops out around 5–10 yards with a wheelbarrow and a plate compactor rental. Call a professional with a skid steer or mini-excavator when: the job needs 10+ yards moved; you're correcting a yard-wide reverse slope toward the foundation; utilities, septic, or drainage easements cross the work area; or you need laser-accurate fall over a long run. A skilled operator finishes in a day what takes a homeowner a weekend — and a wrong grade costs far more in basement water than a day of machine time.

Common mistakes

Grading toward the house. The whole point is fall away from the foundation — verify with a level as you go. Skipping compaction. The #1 cause of the returning swale. Topsoil for the whole wedge. Expensive and it keeps settling. One deep leveling pass. More than ½ inch smothers the lawn — do thin passes. Treating a pit like a slope. Holes, pools, and sinkholes are void math with deeper compaction needs — that's our fill dirt guide, not this one.