How Much Dirt Do I Need? Raised Bed, Topsoil & Fill Dirt Guide

The formula for calculating dirt volume is:

Cubic yards = (Length × Width × Depth in feet) ÷ 27

Convert depth from inches to feet by dividing by 12. A 6-inch depth is 0.5 feet; a 12-inch depth is 1 foot. The shortcut formula combines both steps:

Cubic yards = Square feet × Depth (inches) ÷ 324

For weight: US tons = Cubic yards × Density (tons per cubic yard)

For settling allowance: Order volume = Base volume × (1 + Settling %)

1. Measure the length and width of your project area in feet.
2. Determine the depth needed (typically 4–12 inches depending on project).
3. Calculate cubic feet: length × width × (depth ÷ 12).
4. Convert to cubic yards: divide by 27.
5. Add 15–25% for settling (topsoil settles more than fill dirt).
6. Multiply by density for weight, or by price per cubic yard for cost.

Worked example: 10 × 8 raised bed at 12 inches deep, topsoil:

• Cubic feet: 10 × 8 × 1 = 80 cu ft
• Cubic yards: 80 ÷ 27 = 2.96 cu yd
• With 25% settling: 2.96 × 1.25 = 3.70 cu yd to order
• Weight at 1.0 tons/cu yd: ~3.0 US tons (loose topsoil)
• Cost at $30/cu yd: 3.70 × $30 = $111

Cubic feet is the most useful unit for smaller dirt projects — raised beds, container gardens, and bagged-soil calculations. To calculate cubic feet:

Cubic feet = Length (ft) × Width (ft) × Depth (ft)

If your depth is in inches, convert to feet first by dividing by 12. A 4 × 8 raised bed that is 1 foot deep: 4 × 8 × 1 = 32 cubic feet. A 6-inch depth is 0.5 feet.

To convert cubic feet to cubic yards (for bulk orders), divide by 27. To convert to bags, divide by the bag size in cubic feet.

Raised beds are one of the most common dirt projects. Measure the bed's interior dimensions (not the exterior — the boards take up space) and multiply length × width × depth in feet.

Most raised beds perform best with a blended mix, not pure topsoil. A common recipe is 60% topsoil, 30% compost, and 10% aeration (perlite or vermiculite). Calculate the total volume first, then split it across the ingredients. Add 10–15% for settling in the first season.

Choosing the right dirt matters as much as calculating the right quantity:

Use fill dirt under paved surfaces (driveways, patios) and topsoil where plants will grow. Never use fill dirt in raised beds — it lacks the organic matter and structure plants need.

To convert dirt volume to weight (for delivery truck limits or tonnage pricing), multiply cubic yards by the material's density:

A typical pickup truck safely carries about 1 cubic yard of dirt — larger loads require delivery. Wet dirt can weigh 20–30% more than dry.

Loose dirt delivered by truck takes up more volume than the same dirt after it settles. Always add a settling allowance to avoid under-ordering — the most common dirt-project mistake.

If your project specifies a final compacted depth (for example, a 6-inch raised bed after settling), order enough loose material to reach that depth after settling.

For small raised beds and container gardens, bagged soil is convenient but more expensive. Divide your total cubic feet by the bag size:

Bagged soil costs $2–$8 per bag ($30–$200+ per cubic yard) — significantly more than bulk ($10–$50 per cubic yard). For projects over about 2 cubic yards, bulk delivery is far more economical.

Example: A raised bed needing 3.70 cubic yards of topsoil at $30/cu yd = $111 material + $75 delivery = $186 total. The same project bagged (about 53 bags at $5 each) would cost $265.

For dirt removal, calculate the volume being excavated: length × width × depth ÷ 27 for cubic yards. For a 20 × 10 excavation at 2 feet deep: 20 × 10 × 2 = 400 cubic feet ÷ 27 = 14.8 cubic yards. Add 10–20% for swell — excavated (loose) dirt takes up more volume than compacted dirt.

Dirt removal costs $20–$60 per cubic yard (including hauling and disposal), or $200–$500 per dump truck load. Clean fill dirt can often be given away for free on local listing sites, saving disposal fees. Contaminated soil costs more to dispose of.

Backfill is the dirt used to fill an excavation around a foundation, trench, or structure. Calculate the void volume: (trench length × width × depth) − (structure volume) ÷ 27. For a 30-foot trench at 2 ft wide × 4 ft deep with a 1-ft footing: (30 × 2 × 4) − (30 × 1 × 4) = 120 cubic feet ÷ 27 = 4.44 cubic yards. Add 15% for compaction. Use fill dirt (not topsoil) for backfill.

Black dirt (also called topsoil or loam) is the dark, organic-rich surface soil used for lawns, gardens, and planting beds. It uses the standard formula: area × depth ÷ 27 for cubic yards. For a 500 sq ft lawn at 4 inches: 500 × 0.333 = 166.7 cubic feet ÷ 27 = 6.17 cubic yards. Add 20–25% for settling. Black dirt costs $20–$50 per cubic yard bulk.

To calculate dirt weight, multiply cubic yards by the material’s density. Loose, dry topsoil weighs about 2,000 lb per cubic yard (1.0 US tons). Moist topsoil: 2,200 lb. Fill dirt: 2,200–2,500 lb per cubic yard. Wet dirt can weigh 3,000+ lb per cubic yard.

A typical pickup truck safely carries about 1 cubic yard of dry dirt (2,000 lb) — wet dirt may exceed payload capacity. For delivery, a single-axle dump truck holds 2–5 cubic yards, and a tandem axle holds 10–16 cubic yards.

Instant estimates: dirt calculator. Step-by-step yardage: how to calculate yards of dirt. Fill / grading focus: fill dirt calculator guide. Volume math: cubic yard calculator. Area: square footage calculator. Driveway base: gravel calculator.