Dirt Calculator

Introduction

Ordering dirt is one of the few home improvement tasks where a math error costs real money. Too little topsoil and your raised beds sit half full while the delivery truck drives away; too much fill dirt and you are stuck paying to haul away a pile of sodden clay that settles against the foundation. A cubic yard of soil can weigh a ton or more, so guessing is not a free exercise — it is a choice between overpaying for material you do not need and under-ordering by a full truckload. This calculator converts the three dimensions of your planting area into the two numbers every soil supplier cares about: cubic yards of volume and tons of weight.[umd-fill]

The math itself is straightforward — length times width times depth gives volume, and dividing by 27 converts cubic feet to cubic yards — but the practical decisions hide in the details. What depth do you actually need for a raised bed versus a top-dressing? Which material are you buying, and how much does it weigh per yard? Should you add a waste allowance for settlement and spillage? This tool answers all of those questions in one pass, with a unit toggle so it works in both feet-and-inches and meters-and-centimeters.

Because dirt projects rarely travel alone, this calculator connects to the rest of the Landscape & Ground family. The Mulch Calculator sizes the bark or wood-chip layer that suppresses weeds after you finish spreading the topsoil, and the Gravel Calculator handles the crushed-stone paths and drainage beds that sit beside a garden. The Cubic Yard Calculator is the general volume tool behind all of these, while the Fence Calculator and Retaining Wall Calculator help you plan the structures that frame the beds. For hard surfaces, the Concrete Calculator covers the slabs and footings that will never move an inch.

For more information, see the Gravel Calculator.

For more information, see the Mulch Calculator.

For more information, see the Cubic Yard Calculator.

For more information, see the Fence Calculator.

How to Use

Start by choosing your units. The US setting works in feet for length and width with inches for depth, which matches how most garden beds are planned; the metric setting switches to meters and centimeters for the same job. Then enter the length and width of the area you want to fill, followed by the depth of soil you intend to add, and select the material you are ordering.

The material selector matters because weight is what your budget actually rides on. Topsoil is the screened, nutrient-rich surface layer used to build beds and lawns. Fill dirt is the cheaper unscreened material used for grading and leveling, and it tends to be denser. Compost is the decomposed organic matter that lightens soil and feeds plants, but it weighs barely half as much as mineral soil. Raised bed mix is a blended 50/50 topsoil-and-compost product that many suppliers sell ready to use. Each choice changes the estimated weight in the results even when the volume stays the same.

The over-order allowance deserves a deliberate decision rather than the default. Soils settle, spill, and compact in transit, and most suppliers suggest buying about 10% more than the bare volume. If you are filling a bed that you built with a solid floor, keep the allowance small; if you are topping a sloped lawn or spreading soil that will settle several inches, raise it toward 15-20%. The calculator applies the allowance before computing weight, so your truck-weight estimate already includes the extra material.

Here are three worked examples that show how the same tool handles very different projects.

Example 1 — A standard raised bed. A 4-by-8-foot bed filled to a depth of 12 inches holds 32 cubic feet. With the default 10% allowance that is 35.2 cubic feet, or about 1.3 cubic yards. Ordered as topsoil at roughly 1.05 tons per yard, that is about 1.4 tons of material — usually delivered as two to three bulk bags or one small dump-truck load rather than the 24 individual 1.5-cubic-foot bags the bag-count row suggests.

Example 2 — A lawn top-dressing. Leveling a 20-by-30-foot lawn with a thin 1-inch layer of fill dirt needs 50 cubic feet of base volume, or 55 cubic feet with a 10% allowance — just over 2 cubic yards. Because fill dirt is denser than topsoil, the weight estimate rises to about 2.4 tons. This is exactly the case where the weight row keeps you honest: a small pickup truck bed holds about 2 cubic yards, so this job needs either two trips or a delivery.

Example 3 — A small bed using compost. A 2-by-6-foot bed topped with 3 inches of compost needs just 3 cubic feet, or 3.3 cubic feet with allowance — barely a tenth of a cubic yard. Compost weighs only about 0.54 tons per yard, so the whole job weighs under 200 pounds. For a project this small, three 1.5-cubic-foot bags from a garden center beat renting any delivery, which is exactly what the bag-count row is telling you.

If your bed is not a neat rectangle, measure the length and width at the widest points and accept a small overestimate — irregular shapes are exactly what the waste allowance exists to absorb. For an odd shape you cannot approximate, the Cubic Yard Calculator covers the underlying volume math in more detail.[ask-ext]

The Formula

The volume calculation is a simple rectangular prism: multiply the length by the width to get the area, then multiply the area by the depth.

For US measurements the depth is entered in inches, so it must be converted to feet before the multiplication. Since a cubic yard contains 27 cubic feet, the volume in cubic yards follows directly.

The weight estimate then multiplies the total volume, including the waste allowance, by the material's density. A density of 78 pounds per cubic foot for topsoil is equivalent to about 2,100 pounds per cubic yard, or 1.05 tons. The calculator uses the densities in the table below, which are representative values drawn from the state and federal conversion-factor references cited in this page.[la-volume][nm-conversions]

Walking through Example 1 by hand: 4 feet times 8 feet is 32 square feet. At 12 inches of depth that is 32 cubic feet. Adding 10% gives 35.2 cubic feet, and dividing by 27 yields about 1.30 cubic yards. Multiplying 35.2 cubic feet by 78 pounds per cubic foot gives 2,746 pounds, or about 1.37 tons — matching the calculator's output within rounding.

Reference Table: Soil Weights

Soil density is not a single number, because moisture content and composition swing the weight dramatically. Dry, screened topsoil runs lighter than damp fill pulled straight from a construction pit. The values below are the calculator's working densities, placed next to the published conversion factors that informed them so you can adjust if your supplier quotes a different number.

Published references land in the same range. The County of Los Angeles conversion table lists dry soil at about 2,025 pounds per cubic yard, the EPA's standard conversion factors put soil and sandy loam near 2,400 pounds per cubic yard, and the New Mexico EMNRD conversion sheet quotes roughly 1,600 pounds per cubic yard for both topsoil and fill dirt.[la-volume][epa-conversions][nm-conversions] The spread between 1,600 and 2,400 pounds is mostly moisture: a fresh load of damp soil genuinely can weigh half again as much as the same soil dried out. Compost, by contrast, sits reliably near 1,000 pounds per cubic yard, which is why extension services routinely quote compost at about half the weight of mineral soil.[ask-ext]

Practical Tips

• Buy by the yard, order by the weight. Dump-truck capacity is quoted in cubic yards, but road weight limits and soil density mean a half-load of damp clay can exceed a full load of dry topsoil. Confirm the tonnage with the supplier before the truck rolls.

• Match the depth to the crop. A raised bed for vegetables wants 8-12 inches of mix; a bed for shrubs and perennials wants 12-18 inches. Shallow top-dressing of an existing lawn needs only 1 inch. The University of Maryland Extension recommends filling raised beds with a blend of topsoil and compost rather than pure topsoil, which is why the raised bed mix option exists.[umd-fill]

• Keep compost at the right ratio. For in-ground beds, roughly 25-50% of the total soil volume can be compost, but 100% compost beds compact and drain poorly for most vegetables. The 50/50 raised bed mix is a reasonable starting point; when in doubt, lean slightly toward more topsoil.[epa-compost]

• Weigh the delivery fee against bag counts. A cubic yard equals 18 of the common 1.5-cubic-foot bags. For a project under about a third of a yard, bags usually win; above that, bulk delivery almost always beats the cost and labor of hauling dozens of bags.

• Dump trucks, not pickup trucks, are the yardstick. A full-size pickup bed holds roughly 1.5-2 cubic yards of loose soil before it risks overload. If your order exceeds that, plan for a delivery or a second trip — the weight estimate tells you why.

• Set the allowance before you order, not after. Freshly dumped soil settles several inches as it dries and compacts. If you cannot top up later without a second delivery fee, the 10-15% allowance is cheap insurance.

Limitations

The weight estimate is exactly that — an estimate. Moisture is the largest variable: the same cubic yard of soil can weigh 1,600 pounds bone dry and close to 2,400 pounds right after rain, a swing larger than the difference between material types. If your load is visibly damp, add 10-20% to the weight estimate for trucking and hand-move planning.

The volume math assumes a rectangular prism with vertical sides. Real beds flare outward, lawns slope, and irregular planters do not fill cleanly, so treat the result as a good lower bound rather than a precision measurement. The waste allowance exists precisely to cover the gap.

Soil density claims from suppliers vary for a reason: screening, stone content, organic matter, and moisture all shift the number. When the delivery quote conflicts with the estimate here, trust the supplier's figure for weight but keep this calculator's volume — volume is geometry, and geometry does not argue.

Finally, "dirt" is not one material. Fill dirt used for grading is different from topsoil used for growing, and neither is compost. Ordering the wrong one is a common and expensive mistake that this calculator cannot detect — you have to tell it which material you are buying, and the weight and price consequences follow from there.

Frequently Asked Questions

❓ How much dirt do I need for my garden bed?

✅ Multiply the length by the width by the depth of the bed. A 4-by-8-foot bed filled to 12 inches needs 32 cubic feet, or about 1.2 cubic yards before adding a waste allowance. Enter those three dimensions into this calculator and it returns the volume in cubic feet and cubic yards, plus the weight and bag count.

❓ How many cubic yards are in a ton of topsoil?

✅ A cubic yard of topsoil weighs roughly 1.05 tons at typical moisture, so one ton is about 0.95 cubic yards. Because the weight varies with moisture from about 0.8 to 1.2 tons per yard, it is safer to order by volume and only use weight for truck-planning purposes.

❓ What is the difference between topsoil and fill dirt?

✅ Topsoil is the screened, nutrient-rich surface layer used for growing beds and lawns. Fill dirt is the cheaper unscreened subsoil used for grading, leveling, and backfilling, and it generally contains little organic matter. They are not interchangeable for growing.

❓ How deep should topsoil be for a raised garden bed?

✅ Vegetables and annuals do well with 8-12 inches of soil, while shrubs and perennials prefer 12-18 inches. The University of Maryland Extension recommends filling raised beds with a blend of topsoil and compost rather than pure topsoil.

❓ How much does a cubic yard of dirt weigh?

✅ A cubic yard of dry soil weighs roughly 2,000-2,100 pounds (about 1.05 tons), but damp fill dirt can weigh closer to 2,400 pounds. Compost is much lighter, around 1,000 pounds per cubic yard.

❓ How many bags of topsoil equal a cubic yard?

✅ A cubic yard is 27 cubic feet, which equals 18 of the common 1.5-cubic-foot bags or about 27 of the 1-cubic-foot bags. For more than about a third of a yard, bulk delivery usually costs less than bags and saves the heavy lifting.

❓ Can I fill a raised bed with pure compost?

✅ Pure compost compacts and holds too much water for most vegetables, and it shrinks dramatically as it decomposes. A blend of roughly 25-50% compost by volume with the rest topsoil is the standard recommendation.

❓ Does the calculator work in metric?

✅ Yes. Switch the unit toggle to Metric and enter length and width in meters with depth in centimeters. The results are then reported in cubic meters, tonnes, and 50-liter bags.

❓ Why do I need to add a waste allowance?

✅ Soil settles, spills, and compacts during transit and spreading. A fresh load can settle several inches after it is dumped, and irregular beds hide gaps that fill with extra material. A 10% allowance is the standard practice and is cheap insurance against a second delivery fee.

❓ How many cubic yards fit in a pickup truck?

✅ A full-size pickup bed holds about 1.5-2 cubic yards of loose soil, and that is already at the limit of the truck's payload rating. For orders larger than that, plan on a dump-truck delivery or multiple trips.