Dirt Calculator

To figure out how much dirt you need, calculate the volume of your project area. Measure length, width, and depth in feet, then multiply them together for cubic feet. Divide by 27 for cubic yards (the standard unit for bulk dirt orders). For example, a 10 × 8 raised bed at 12 inches deep needs 10 × 8 × 1 = 80 cubic feet ÷ 27 = 2.96 cubic yards.

Dirt settles after placement, so always add an allowance on top of your calculated volume. Topsoil settles 20–30% (add 25%), while fill dirt settles 10–15% (add 10–15%). Without this allowance, you will end up short — under-ordering is the most common mistake with dirt projects. Order the adjusted volume to reach your target compacted depth.

Dirt is sold three ways: bulk (by the cubic yard, delivered by truck), bagged (by the cubic foot, from a home center), and sometimes by the ton. Bulk is cheapest for projects over about 2 cubic yards; bagged is convenient for small raised beds and repairs. For a full walkthrough, see how much dirt do I need.

A fill dirt calculator uses the same volume math as a general dirt calculator, but you should pick fill-dirt density and a lower settling factor. Fill dirt (subsoil) is for grading, leveling, backfill, and structural pads — not planting beds. Formula: cubic yards = length × width × depth (ft) ÷ 27. Example: 20 × 10 at 6 inches = 3.70 cubic yards; add 10–15% and order about 4.1–4.3 cubic yards.

Fill dirt typically costs $5–$15 per cubic yard bulk and weighs about 1.1–1.25 US tons per cubic yard. For compaction on a slope or under a pad, place in thin lifts and tamp. Full fill-dirt guidance: fill dirt calculator guide. Convert area alone with the square feet to cubic yards converter.

For a garden bed dirt calculator workflow, measure the bed interior, choose planting depth (often 6–12 inches), and convert to cubic yards. A 4 × 8 bed at 12 inches needs 32 cubic feet (1.19 cubic yards) before settling. Use topsoil or a topsoil–compost blend — not fill dirt — so plants have organic matter and drainage.

Small beds are easy with bagged soil; larger beds are cheaper with bulk topsoil. Add 10–15% so the bed stays full after the first season. Pair this tool with the cubic yard calculator when you only need volume math, or the raised-bed table below for common sizes.

Cubic feet is the most useful unit for smaller dirt projects — raised beds, container gardens, and bagged-soil calculations. To calculate cubic feet, multiply length × width × depth, all in feet. A 4 × 8 raised bed that is 1 foot deep: 4 × 8 × 1 = 32 cubic feet.

If your depth is in inches, convert to feet first by dividing by 12. A 6-inch depth is 0.5 feet; a 4-inch depth is 0.333 feet. Once all three dimensions are in feet, the multiplication gives you cubic feet directly. To convert to cubic yards (for bulk orders), divide by 27; to convert to bags, divide by the bag size in cubic feet.

For irregular shapes — an L-shaped garden bed, for example — break the area into rectangles, calculate each volume separately, and add the results. For round beds, use the cylinder formula: π × radius² × depth.

Raised beds are one of the most common dirt projects. To calculate how much soil you need, measure the bed's interior dimensions (not the exterior — the boards take up space) and multiply length × width × depth in feet. A standard 4 × 8 foot raised bed, 12 inches deep, needs 32 cubic feet (about 1.2 cubic yards) of soil mix.

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) — sometimes called "Mel's Mix" or a 5-way blend. Calculate the total volume first, then split it across the ingredients. Add 10–15% for settling in the first season; raised-bed soil drops noticeably as it consolidates.

Choosing the right dirt matters as much as calculating the right quantity. The two main types serve very different purposes:

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. For structural fill under buildings, use engineered fill that has been tested for compaction.

To convert dirt volume to weight (for delivery truck limits or tonnage pricing), 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 and fill dirt are heavier at 2,200–2,500 lb per cubic yard. A typical pickup truck safely carries about 1 cubic yard of dirt — larger loads require delivery.

Loose dirt delivered by truck takes up more volume than the same dirt after it settles and compacts. Topsoil — full of organic matter and air pockets — settles the most, often 25–30% in the first season. Fill dirt settles less (10–15%) but still needs an allowance.

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. The table below shows typical settling factors and the extra volume to order.

For small raised beds and container gardens, bagged soil from a home center is convenient. Bags are sold by cubic feet, so divide your total cubic feet by the bag size. One cubic yard (27 cubic feet) equals 27 one-cubic-foot bags, 18 one-and-a-half-cubic-foot bags, or 13.5 two-cubic-foot bags.

Bagged soil costs $2–$8 per bag, which works out to $30–$200+ per cubic yard — significantly more than bulk delivery ($10–$50 per cubic yard). For projects over about 2 cubic yards, bulk delivery is far more economical. But for a single 4 × 4 raised bed needing under 1 cubic yard, bags avoid the delivery fee and minimum load.