Cubic Feet Calculator

1. Choose your measurement type. Use "Length × Width × Height" for boxes, rooms, and containers. Use "Area × Depth" when you already know the square footage and just need to add a depth for material coverage.
2. Enter your dimensions. Type each measurement and pick the unit you measured in. The calculator converts everything to feet automatically.
3. Pick a material buffer if needed. For loose materials like soil, mulch, or gravel, add 5% to 10% because uneven ground and settling reduce the effective depth after you spread and compact the material.
4. Read the results. Cubic feet is the primary result. Use cubic yards when ordering bulk landscape materials, since most suppliers quote by the yard. Use gallons when filling tanks, pools, or containers.

Pro tip: Measure at three points and average them. Floors, yards, and excavation areas are rarely perfectly flat, and averaging prevents under-ordering.

Cubic feet (also abbreviated as ft³ or CFT) measures the volume of a rectangular space. One cubic foot is a cube that is 1 foot long, 1 foot wide, and 1 foot tall.

Main formula:

Cubic feet = Length (ft) × Width (ft) × Height (ft)

If you already know the area in square feet:

Cubic feet = Area (sq ft) × Depth (ft)

Variables:

• Length = longest side of the space, in feet
• Width = shorter side, in feet
• Height or Depth = vertical measurement or material thickness, in feet
• Area = surface area in square feet (length × width, already calculated)

Unit conversion reference:

Example:

A landscape bed measures 10 ft × 6 ft and you want 3 inches of mulch.

• Area = 10 × 6 = 60 sq ft
• Depth in feet = 3 / 12 = 0.25 ft
• Cubic feet = 60 × 0.25 = 15 ft³
• Cubic yards = 15 / 27 = 0.56 yd³
• With 10% buffer = 0.61 yd³

Most landscape suppliers sell by the cubic yard, so you'd order about 0.6 yards for this bed.

Assumptions:

• The space has straight sides and uniform depth
• No compaction adjustment is applied to the base volume
• For irregular L-shaped or T-shaped areas, split into rectangles and add the volumes
• Loose materials like mulch, soil, and gravel settle 10% to 20% after spreading. Mulch settles the most. Compacted gravel settles less.

Common mistakes:

• Multiplying inch values directly and reading the result as cubic feet. The answer is actually in cubic inches, not cubic feet. I made this mistake measuring a storage unit once and ordered 1,728 times more material than I needed before catching the error.
• Confusing square feet with cubic feet. Square feet measures area (floor space), cubic feet measures volume (the full 3D space).
• Rounding intermediate values instead of rounding only the final result
• Using outside appliance dimensions when you need inside usable space. For refrigerators or freezers, always measure the interior.