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Cubic Feet Calculator

Determining the volume of a rectangular space in cubic feet is essential for construction, landscaping, storage, and material estimation. Whether you're ordering topsoil for a garden bed, sizing a shipping container, or assessing room capacity, cubic footage tells you exactly how much three-dimensional space you're working with. This calculator converts your measurements into cubic feet instantly, regardless of whether you input dimensions in inches, yards, metres, or centimetres.

Last updated:

Creators Karolina Tórzala, MSc
Reviewers Wojciech Sas and Filip Derma
4,072 people find this calculator helpful

The Volume Formula for Cubic Feet

The foundation of any cubic footage calculation is straightforward multiplication. You take your three linear dimensions and multiply them together. The critical requirement is that all dimensions must be in feet before you perform the calculation.

Volume (cubic feet) = Length × Width × Height

  • Length — The longest horizontal dimension, measured in feet
  • Width — The shorter horizontal dimension, measured in feet
  • Height — The vertical dimension, measured in feet

Converting Units Before Calculating

If your measurements aren't already in feet, you'll need to convert them first. Here are the most common conversion factors:

  • Inches to feet: Divide by 12 (since 12 inches = 1 foot)
  • Yards to feet: Multiply by 3 (since 1 yard = 3 feet)
  • Centimetres to feet: Divide by 30.48 (the conversion factor)
  • Metres to feet: Multiply by 3.281 (approximately)

For example, if your oven measures 30 inches wide, 36 inches tall, and 25 inches deep, you'd first convert each dimension: 30÷12 = 2.5 ft, 36÷12 = 3 ft, and 25÷12 ≈ 2.083 ft. Then multiply: 2.5 × 3 × 2.083 ≈ 15.6 cubic feet.

Calculating Cubic Feet for Bulk Materials

When ordering soil, sand, gravel, or mulch, you're typically buying by volume. First, determine the footprint area you need to cover, then multiply by the desired depth.

  • For a rectangular garden bed 20 feet long and 8 feet wide that you want to fill 1 foot deep: Area = 20 × 8 = 160 sq ft; Volume = 160 × 1 = 160 cubic feet
  • Most landscape suppliers sell these materials in cubic yards (which equal 27 cubic feet), so you might divide your result by 27 for ordering purposes

This approach works equally well for concrete pours, gravel driveways, and compost applications.

Common Pitfalls When Calculating Cubic Footage

Avoid these frequent mistakes that lead to ordering too much or too little material.

  1. Mixing unit systems — Converting some dimensions but forgetting others is the most common error. Double-check that all measurements are in feet before multiplying. If you're working from a mixed unit source (some inches, some feet), convert everything first.
  2. Confusing depth with height — In landscaping projects, the vertical measurement is called 'depth' even though the formula uses height. A 3-inch depth of mulch is only 0.25 feet, not 3 feet—many people forget to convert this small measurement.
  3. Rounding prematurely — Rounding intermediate results can accumulate error, especially in large projects. Keep decimals through your calculation and only round the final cubic footage result.
  4. Forgetting to account for settling — Loose materials like soil and gravel settle over time. Professionals often add 10–15% extra volume to compensate for this natural compaction.

Moving Between Cubic Feet and Other Units

Once you have cubic feet, converting to other volume units is simple division or multiplication:

  • Cubic feet to cubic yards: Divide by 27 (since 1 yard = 3 feet, and 3³ = 27)
  • Cubic feet to gallons: Multiply by 7.48 (US gallons)
  • Cubic centimetres to cubic metres: Divide each dimension in centimetres by 100 first, then multiply, or divide the final cubic centimetre result by 1,000,000

These conversions are especially useful when comparing supplier quotes or working across different regional standards.

Frequently Asked Questions

What's the volume of a cube measuring 5 feet on each side?

Multiply 5 × 5 × 5 = 125 cubic feet. This represents a perfect cube where length, width, and height are identical. Such uniform dimensions are common in standardized storage containers and modular room designs.

How do I convert cubic feet to cubic yards?

Divide the cubic footage by 27. Since one yard equals three feet, and volume is three-dimensional, you're dividing by 3³ = 27. If you have 810 cubic feet of soil, that equals 810 ÷ 27 = 30 cubic yards. This conversion is essential for landscape material ordering, since suppliers typically quote yards rather than feet.

Why is cubic footage important for shipping and storage?

Carriers and storage facilities charge based on how much space your goods occupy, not just their weight. Understanding cubic footage helps you choose the right container size, estimate costs accurately, and pack efficiently. A small but dense object might weigh more than a large, lightweight box, but the space it takes matters for billing.

Can I calculate cubic metres directly from centimetres?

Yes, but you must convert first. Divide each dimension in centimetres by 100 to get metres, then multiply all three together. Alternatively, multiply the three centimetre dimensions together, then divide the result by 1,000,000. For instance, 200 cm × 150 cm × 100 cm = 3,000,000 cm³, which equals 3 cubic metres (3,000,000 ÷ 1,000,000).

What does 1 cubic foot actually represent?

One cubic foot is the volume inside a cube measuring exactly 1 foot on each side. Multiply 1 × 1 × 1 = 1 ft³. It's roughly equivalent to a large watermelon or a small laundry basket. Understanding this reference point helps you mentally verify whether your calculated results seem reasonable.

How much cubic footage of soil do I need for a 10 × 3 yard garden bed at 6 inches deep?

First, convert yards to feet: 10 yards = 30 feet, 3 yards = 9 feet. The area is 30 × 9 = 270 square feet. Depth of 6 inches = 0.5 feet. Volume = 270 × 0.5 = 135 cubic feet, or 135 ÷ 27 = 5 cubic yards. Always convert the depth measurement carefully, as it's typically the easiest to overlook.

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