Cubic Yard Calculator for Rectangle

This calculator works out the volume of a rectangular space in cubic yards. You enter the length, width, and depth (or height) of the rectangle, and it returns the volume in cubic yards, plus the equivalent in cubic feet and cubic meters for convenience. It is the standard calculation for ordering fill dirt, gravel, mulch, concrete, or estimating how much material a rectangular hole or container can hold.

Formula

The formula for the volume of a rectangular prism is:

Volume (cubic yards) = (Length × Width × Depth) ÷ 27

Where:

• Length (L) is the longest side of the rectangle, in feet.
• Width (W) is the shorter side, in feet.
• Depth (D) is the thickness or height of the material, in inches (converted to feet by dividing by 12).
• 27 is the number of cubic feet in one cubic yard (3 ft × 3 ft × 3 ft).

If you measure depth in feet instead of inches, skip the /12 step: Volume = (L × W × D in feet) ÷ 27.

Worked Example

Using the default values from the calculator above: length = 10 ft, width = 5 ft, depth = 4 in.

1. Convert depth to feet: 4 in ÷ 12 = 0.3333 ft
2. Calculate volume in cubic feet: 10 × 5 × 0.3333 = 16.6665 ft³
3. Convert to cubic yards: 16.6665 ÷ 27 = 0.6173 yd³

The calculator rounds to two decimals, so the result is 0.62 cubic yards. The cubic feet output is 16.7 ft³, and the cubic meters output is 0.47 m³.

Why Use Cubic Yards?

Cubic yards are the standard unit for bulk landscaping and construction materials in the United States. When you order topsoil, gravel, sand, or concrete from a supplier, they typically quote prices per cubic yard. A cubic yard is a cube that is 3 feet on each side, which is roughly the size of a washing machine. Knowing the cubic yardage of your rectangular area tells you exactly how much material to order, avoiding both shortages and costly overages.

For example, a garden bed that is 20 ft long, 4 ft wide, and 6 in deep needs 20 × 4 × 0.5 = 40 ft³, which is 40 ÷ 27 = 1.48 yd³. You would order 1.5 cubic yards (or 2 if the supplier only sells whole yards).

How to Measure a Rectangle Correctly

Accurate measurements are the key to a correct volume. Follow these steps:

• Use a tape measure or laser measure for length and width. Measure in feet; if you have inches, convert them to feet (e.g., 12 ft 6 in = 12.5 ft).
• For depth, measure the actual thickness of the material you plan to add. For a new bed, that’s the height of the retaining wall or the depth of the hole. For mulch, a typical depth is 2–3 inches; for gravel, 4–6 inches.
• If the area is not a perfect rectangle, divide it into rectangular sections, calculate each, and add them together.
• Always measure in the same unit. The calculator uses feet for length/width and inches for depth, but you can use any unit as long as you convert consistently.

Common Mistakes and Misconceptions

The most frequent error is mixing units without converting. For instance, multiplying length in feet by width in feet by depth in inches gives a meaningless number. Always convert depth to feet first.

Another common mistake is forgetting that a cubic yard is 27 cubic feet, not 3. Some people erroneously divide by 3, which would give a volume three times too large.

A related misconception is confusing cubic yards with square yards. Square yards measure area (length × width ÷ 9), not volume. You need depth to get cubic yards.

Rounding too early can also throw off your order. If you round the depth to 0.3 ft instead of 0.333, your volume will be off by about 10%. Keep full precision until the final step.

When to Use This Calculator

This calculator is ideal for any project that involves filling or excavating a rectangular space:

• Landscaping: ordering mulch, topsoil, or compost for garden beds.
• Construction: estimating concrete for a slab or footings, or fill for a foundation.
• Hardscaping: gravel or sand for a patio base, walkway, or driveway.
• Moving/Storage: estimating the volume of a moving truck or storage container (though interior dimensions are often in feet, so measure carefully).

For irregular shapes, break the area into rectangles and sum the results. For a triangle, use the formula (base × height × depth ÷ 2) ÷ 27.

Limitations of the Formula

The formula assumes a perfect rectangular prism with uniform depth. Real-world conditions can differ:

• Ground may not be level, so depth varies. Take multiple depth measurements and average them.
• Material compacts. For example, gravel compacts about 10–15% when tamped. Order extra (usually 10–20%) for compaction.
• For concrete, you typically order by the cubic yard, but ready-mix trucks have minimum orders (often 1–2 yards).
• For soil or mulch, the volume may settle after rain or over time.

Always confirm with your supplier whether the quoted cubic yard is loose or compacted, and ask about delivery fees.

Frequently Asked Questions

How many cubic feet are in a cubic yard?

There are 27 cubic feet in one cubic yard because a yard is 3 feet, and 3 × 3 × 3 = 27. This is why the formula divides by 27.

Can I use this calculator for circular areas?

No, this calculator is only for rectangles. For a circle, use the formula: π × (radius in ft)² × (depth in ft) ÷ 27. You can use a separate circle calculator or compute manually.

What if my depth is in feet instead of inches?

You can still use the calculator by entering the depth in inches (multiply feet by 12). Or simply divide the result by 27 after calculating cubic feet manually.

How much extra material should I order?

For most bulk materials, add 5–10% for waste and settling. For compaction (gravel, sand), add 10–20%. For concrete, order exactly what you need, but consider a small overage (e.g., 0.5 yard) to avoid running short.

Does this work for metric measurements?

The calculator uses feet and inches, but you can convert metric to feet (1 m = 3.28084 ft) or use the cubic meters output for reference. For a purely metric calculation, use length (m) × width (m) × depth (m) to get cubic meters.

What is the difference between cubic yard and square yard?

A square yard measures area (2D), equal to 9 square feet. A cubic yard measures volume (3D), equal to 27 cubic feet. You need depth to convert between them.

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in l | Length | ft | 10 | 0
in w | Width | ft | 5 | 0
in d | Depth | in | 4 | 0
out yd3 | Volume | cubic yards | (l * w * (d / 12)) / 27 | 2
out ft3 | Volume | cubic feet | l * w * (d / 12) | 1
out m3 | Volume | cubic meters | (l * w * (d / 12)) * 0.0283168 | 2