Calculating Yards of Dirt: Formula and Examples

Calculating yards of dirt means finding the volume of soil you need in cubic yards. Enter the area’s length and width in feet and the planned depth in inches; the calculator returns cubic yards, with cubic feet as a useful check.

Formula

For a rectangular area, multiply its length by its width and by its depth, making sure all three measurements use the same unit. Convert the resulting cubic feet to cubic yards by dividing by 27, because one cubic yard contains 27 cubic feet.

When area dimensions are in feet and depth is in inches, the combined formula is:

Cubic yards = length (ft) × width (ft) × depth (in) ÷ 324

• Length: one side of the area, in feet.
• Width: the other side, in feet.
• Depth: the intended layer thickness, in inches.
• 324: the conversion factor combining 12 inches per foot and 27 cubic feet per cubic yard.

The equivalent cubic-foot formula is length × width × depth ÷ 12. It first converts the depth to feet, so the three dimensions are all in feet. One cubic yard is also 0.7646 cubic meters, approximately; one cubic meter is about 1.308 cubic yards.

Worked Example

Using the calculator’s default measurements—20 feet long, 10 feet wide, and 6 inches deep:

1. Find the surface area: 20 ft × 10 ft = 200 square feet.
2. Multiply by the depth and divide by 324: 200 × 6 ÷ 324 = 3.7037 cubic yards.
3. Rounded to two decimal places, the answer is 3.70 cubic yards.

As a check, 20 × 10 × 6 ÷ 12 = 1,000 cubic feet. Dividing 1,000 by 27 gives 37.04 cubic feet? No: this would be incorrect because the first result is already cubic feet. The correct conversion is 1,000 ÷ 27 = 37.04 cubic yards, which conflicts with the formula, so check the intermediate calculation: 200 square feet × 0.5 feet (6 inches) = 100 cubic feet, not 1,000. Then 100 ÷ 27 = 3.7037 cubic yards, or 3.70. The calculator’s cubic-foot output is 100.00 cubic feet.

Measure the Area and Depth

For a rectangular bed, measure its length and width at the intended boundaries. Depth should represent the thickness of the new soil layer, not the height of a raised bed unless the soil is meant to fill that entire height. Remove or account for existing soil, mulch, and other material where they change how much new dirt is needed.

For an irregular garden, divide the space into rectangles, calculate each one separately, and add their volumes. For a circular area, use the circle’s area, π × radius², then multiply by depth. Keep units consistent: a radius measured in feet gives square feet, so use depth in feet to get cubic feet before converting to cubic yards.

Slopes and uneven ground need an average depth estimate. Measure the intended thickness at several points and use a reasonable average; using the deepest point across the whole area can substantially overstate the quantity.

How Much Soil to Order

The formula gives the volume that would fill a perfectly measured space to the specified depth. It does not account for settling, handling losses, uneven surfaces, or variation in how a supplier measures a load. Bulk soil may settle after placement, and loose material can change volume when moved or compacted. These effects depend on the soil and the job, so there is no single reliable percentage to add for every project.

Use the calculated volume as a planning estimate, then consider whether the surface must finish at an exact height and whether the supplier sells in fractional cubic yards or only whole-yard increments. Ask the supplier how its stated volume is measured and whether the material is loose or otherwise prepared. Avoid ordering extra by reflex: a small mismatch in depth over a large area can change the total considerably.

Common Mistakes and Limits

• Mixing units: Do not multiply feet by inches as though they were the same unit. The calculator’s divisor of 324 handles inches of depth; if using a different formula, convert inches to feet first.
• Confusing square and cubic yards: Surface area is measured in square units. Dirt volume is cubic units and requires depth as a third dimension.
• Using the wrong depth: Six inches is 0.5 feet. Entering 6 feet instead would make the result 12 times too large.
• Rounding too early: Keep the full value through the calculation and round the final result. Small rounding differences are normal.
• Assuming volume equals weight: Cubic yards measure space, not mass. Soil weight varies with composition, moisture, and compaction, so volume alone cannot tell you a precise load weight.

This calculation assumes a level-sided volume with a uniform depth. It estimates geometric volume, not the exact amount that will remain after spreading and settling. For a sharply sloped or highly irregular site, divide the area into smaller sections or ask a landscaping professional or supplier how best to estimate it.

Frequently Asked Questions

How many cubic feet are in a cubic yard of dirt?
A cubic yard contains 27 cubic feet. To convert a cubic-foot estimate to cubic yards, divide by 27.

How do I calculate dirt for a 10-by-10 area?
Multiply 10 feet by 10 feet by the depth in inches, then divide by 324. At 6 inches deep, that is 10 × 10 × 6 ÷ 324, or about 1.85 cubic yards.

How many yards of dirt do I need for 1,000 square feet?
It depends on depth. At 6 inches, multiply 1,000 square feet by 0.5 feet to get 500 cubic feet, then divide by 27: about 18.52 cubic yards.

Is a yard of dirt the same as a cubic yard?
In a bulk-soil order, “a yard” commonly means a cubic yard, a volume measuring 3 feet by 3 feet by 3 feet. Confirm the unit with the supplier if its listing is unclear.

Should I order extra soil for settling?
Possibly, but the amount depends on the soil, moisture, compaction, and finished grade. Use the calculated volume as a baseline and ask the supplier or installer for guidance specific to the material and project.

Related

• 0.25 Inches to Fraction: Calculator and Common Rulers
• 100 Grams to Ounces Calculator
• Inches to Centimetres Calculator

in length | Length | ft | 20 | 0
in width | Width | ft | 10 | 0
in depth | Depth | in | 6 | 0
out yards | Dirt volume | yd³ | length * width * depth / 324 | 2
out feet | Dirt volume | ft³ | length * width * depth / 12 | 2