Cubic Yard Calculator

What is a cubic yard calculator?

A cubic yard calculator converts the size of a three-dimensional space into cubic yards. It is useful when ordering or estimating bulk materials such as topsoil, mulch, compost, gravel, sand, fill and concrete, and when measuring excavation or backfill volume.

A cubic yard is a unit of volume, not area and not weight. One yard is 3 feet long, but one cubic yard is a cube that is 3 feet long, 3 feet wide and 3 feet high. That makes exactly 27 cubic feet. NIST's current U.S. measurement tables likewise define 27 cubic feet as one cubic yard.

This page keeps that exact geometry at the centre of the calculation. It does not automatically turn yards into tons because the weight of a cubic yard depends on the material's bulk density. If you need a material-specific weight estimate, use a calculator designed for that material, such as the SonoCalculator Gravel Calculator.

How to calculate cubic yards

When all dimensions are in feet

For a rectangular box, trench, bed or layer, multiply length by width by depth to get cubic feet. Then divide by 27:

For example, a space 12 feet long, 9 feet wide and 0.5 feet deep contains 54 cubic feet. Dividing 54 by 27 gives exactly 2 cubic yards.

When depth is measured in inches

Landscaping and shallow construction layers are often measured in feet across the surface but inches in depth. Convert the inches to feet by dividing by 12, then divide cubic feet by 27. You can combine those two conversions into one shortcut:

The number 324 is not an approximation: it is 12 × 27. Twelve converts inches to feet and 27 converts cubic feet to cubic yards.

Square feet to cubic yards: you need a depth

Square feet and cubic yards measure different things. Square feet describe area; cubic yards describe volume. There is no valid direct conversion unless you know the missing third dimension: depth or thickness.

Once depth is known, the conversion is straightforward:

This is why the calculator includes a Known area mode. If a site plan, survey or our Square Footage Calculator has already given you the area, you can enter that number directly rather than re-entering length and width.

How much area does one cubic yard cover?

Coverage depends entirely on depth. The same cubic yard spreads over a large area when the layer is thin and a much smaller area when it is thick. Since one cubic yard contains 27 cubic feet, or 324 square-foot-inches of volume, coverage can be calculated as:

The table is pure volume geometry. It does not decide what depth is appropriate for a particular material or structural application.

Rectangle, circle and triangle formulas

Rectangular area

Most beds, pads, trenches and slabs can be approximated as rectangles.

Circular area

For a round bed, circular pad or other circular layer, measure the diameter. Radius is half the diameter:

Triangular area

For a triangle, use the perpendicular height—not the sloping side:

After finding area, multiply by depth to obtain volume. The calculator handles the required unit conversion automatically.

Worked example: 20 ft × 12 ft at 4 inches deep

Suppose a rectangular project is 20 feet long, 12 feet wide and 4 inches deep. First calculate area:

Then use the square-feet-and-inches shortcut:

So the theoretical volume is about 2.96 cubic yards. If you intentionally choose a 10% ordering allowance:

If your supplier sells only in half-yard increments, rounding up to the next 0.5 yd³ gives a 3.5 yd³ order. Notice that the calculator keeps three ideas separate: exact geometric volume, your chosen allowance, and the supplier's selling increment.

Why ordering allowance and supplier rounding are separate

Many calculators automatically add 5%, 10% or more and call it waste, settlement or compaction. That can hide important assumptions. Different projects have different sources of uncertainty: an irregular excavation may need contingency for grade variation, while a precisely formed concrete volume has a different reason for overage than a mulch bed.

SonoCalculator therefore leaves the allowance blank until you choose one. It is simply:

Supplier rounding is a different step. A landscape yard might sell quarter-yard or half-yard increments; another supplier may sell whole yards; ready-mix concrete practices may differ again. Choose a rounding increment only if it matches the way your supplier sells.

Cubic yard conversions

Because a cubic yard is a defined unit of volume, its conversion to other volume units is fixed. The most useful construction and landscaping conversions are:

The calculator's Convert volume mode can also work backwards from cubic feet, cubic metres, litres or cubic inches to cubic yards.

Cubic feet to cubic yards

If you already know cubic feet, no area or depth calculation is necessary. Divide by 27:

For example, 81 cubic feet ÷ 27 = 3 cubic yards. Conversely, multiply cubic yards by 27 to obtain cubic feet.

Cubic metres to cubic yards

Metric volume can be converted directly. One cubic metre is approximately 1.30795062 cubic yards, while one cubic yard is exactly 0.764554857984 cubic metres based on the exact yard-to-metre definition.

If you are measuring a project in metres and centimetres, you do not need to convert each dimension manually. In Metric mode the calculator finds cubic metres first and then converts the result to cubic yards.

Using cubic yards for mulch

Mulch is commonly ordered by volume, making cubic yards directly useful. Measure the actual bed area and choose the finished depth appropriate to the landscaping plan. Existing mulch, plant crowns, slopes and irregular edges can make field conditions differ from a perfect geometric layer.

For multiple beds, calculate each area separately or combine their accurately measured square footage. If several beds have the same area and depth, the quantity input can multiply identical sections. For material-specific planning and bag comparisons, use the SonoCalculator Mulch Calculator.

Using cubic yards for topsoil, compost and fill

Topsoil and fill estimates often involve uneven existing grades. A simple length × width × depth calculation assumes a uniform layer. If one end needs 2 inches and another needs 8 inches, using either extreme for the entire site can be misleading. A practical estimate may use measured sections or an average depth derived from grade information.

For raised beds and planters with straight sides, internal length × internal width × fill depth gives a useful volume. Subtract large permanent objects if they occupy meaningful space. For major grading or earthwork, surveyed surfaces and cut/fill software are more appropriate than a single average-depth rectangle.

Using cubic yards for gravel and aggregate

Cubic yards tell you how much space the aggregate occupies; they do not tell you its weight. Gravel and crushed stone are also frequently sold by ton, and the conversion depends on bulk density, grading, moisture and material source.

Use this calculator when the supplier sells by volume or when you need the geometric yardage. Use the Gravel Calculator when you also need a density-based estimate in tons or tonnes. Keeping those calculations separate avoids the common mistake of treating one cubic yard as though it always weighs one ton.

Using cubic yards for concrete

Ready-mix concrete is commonly specified by volume, but concrete ordering has project-specific concerns such as form dimensions, slab thickness, footings, beams, waste, placement losses and supplier minimums. A slab's geometric volume can be calculated in cubic yards exactly from its dimensions, but the quantity to order may intentionally be larger.

For a simple rectangular slab:

For concrete-specific shapes and ordering, use the SonoCalculator Concrete Calculator. This general Cubic Yard Calculator is best used as the universal volume tool.

Excavation and backfill volume

A rectangular excavation can be estimated with the same volume formula as material placed into a space. A 30 ft trench that is 2 ft wide and 3 ft deep contains 180 cubic feet, or about 6.67 cubic yards of geometric excavation.

However, excavated soil does not necessarily occupy the same volume once disturbed. Soil can swell when excavated and shrink when compacted as fill. Those factors vary with soil type, moisture and compaction requirements. This calculator intentionally reports geometric volume and does not apply a universal swell or shrink factor.

Irregular and sloped areas

For irregular shapes, divide the site into simpler measurable sections—rectangles, circles and triangles—then add their volumes when the depth is consistent. If depth varies, calculate sections separately. This is usually more defensible than multiplying the maximum length, maximum width and maximum depth.

For a long path with nearly constant width, length × average width can be practical. For a tapered area, splitting it into a rectangle and triangle may be more accurate. For major earthworks, complex slopes or high-value material orders, field measurements or surveyed surfaces should replace rough shape approximations.

Multiple areas and repeated sections

Repeated garden beds, post bases, pads or identical sections do not need to be entered one by one. Calculate one section and use the quantity field. The calculator multiplies the geometric volume before applying the ordering allowance, which is mathematically equivalent to applying the same allowance to each identical section.

If sections have different dimensions or depths, calculate them separately and add the theoretical cubic yards. Apply an overall allowance only after you understand whether the same uncertainty reasonably applies to all sections.

Estimating material cost per cubic yard

If your supplier quotes a price per cubic yard, enter that rate in the optional cost field. The calculator multiplies the final supplier-rounded order quantity when rounding is selected; otherwise it uses the volume after allowance.

This is a material-only estimate. Delivery, taxes, minimum-load charges, equipment, labor, excavation, disposal and other project costs are not included unless they are already built into the unit price you enter.

Common cubic-yard calculation mistakes

• Dividing a length by 27. The ÷27 conversion applies to cubic feet, not ordinary feet.
• Forgetting to convert depth in inches. Use depth ÷12 before multiplying in feet, or use the ÷324 shortcut.
• Trying to convert square feet without depth. Area alone cannot determine volume.
• Confusing square yards with cubic yards. Square yards measure area; cubic yards measure three-dimensional volume.
• Treating cubic yards as tons. Weight requires material density.
• Automatically adding 10% to every project. Allowance should reflect the actual project and material.
• Rounding too early. Keep precision through the geometry, then round the final order according to the supplier's selling increment.
• Using maximum dimensions for irregular work. Divide irregular sites into smaller shapes when accuracy matters.

How to measure before ordering bulk material

Measure finished dimensions rather than guessing from visual size. Check length and width in more than one location when edges are not parallel. Confirm whether the stated depth is the final installed depth, loose placement depth or a design thickness after compaction. Record units as you measure so feet, inches, metres and centimetres are not accidentally mixed.

Before a large order, ask the supplier how the material is sold, the smallest increment they will load, whether delivery has a minimum quantity, and whether a quoted price includes delivery. For weight-sold materials, ask for the supplier's volume-to-weight conversion for the exact product.

Frequently asked questions

Final note: SonoCalculator's Cubic Yard Calculator separates exact unit conversion from project assumptions. The 27 ft³-per-yd³ conversion is exact; project dimensions, depth, ordering allowance, compaction, material behavior and supplier increments are real-world inputs that must match your job. For large, structural or engineered work, use the dimensions and material requirements from the applicable plans or specification.