Quick answer
Multiply length × width × depth in feet to get cubic feet, then divide by 27 for cubic yards. Convert depth from inches to feet before multiplying.
Step by step
- Measure length and width. Use feet.
- Convert depth to feet. Divide inches by 12.
- Calculate cubic feet. Multiply length × width × depth.
- Convert to cubic yards. Divide by 27 and apply any project allowance.
Formula or rule of thumb
cubic yards = length(ft) × width(ft) × depth(ft) ÷ 27
Example
A 20 × 10 ft bed at 3 in deep is 20 × 10 × 0.25 ÷ 27 ≈ 1.85 yd³.
Common mistakes
The most common mistake is multiplying by depth in inches without converting to feet first.
Planning note: product yields, installation methods, site conditions and local requirements can change the final quantity. Use the exact manufacturer or supplier information before purchasing.
FAQ
Is a cubic yard always 27 cubic feet?
Yes, by unit conversion.
Can I use this for mulch and gravel?
Yes for geometric volume, but weight and compaction differ by material.
Should I add extra material?
A project allowance may be useful for settlement, grading and measurement uncertainty, depending on the material and job.