Square Feet to Cubic Feet Calculator
Enter area and depth — get cubic feet and cubic yards in real time. The most common landscaping math.
Area vs Volume
Square feet (ft²) measure a 2D area — a flat surface like a floor or yard. Cubic feet (ft³) measure 3D volume — the space something occupies. To go from area to volume, multiply by a depth or thickness in the same unit (feet).
Volume (ft³) = Area (ft²) × Depth (ft)
Depth Reference Table
| Depth (inches) | Depth (feet) |
|---|---|
| 1 | 0.083 |
| 2 | 0.167 |
| 3 | 0.25 |
| 4 | 0.333 |
| 5 | 0.417 |
| 6 | 0.5 |
| 8 | 0.667 |
| 10 | 0.833 |
| 12 | 1 |
Use Cases
Landscaping
The classic application — multiply bed area in square feet by mulch/soil depth in feet. A 200 sq ft bed at 3 in (0.25 ft) mulch depth needs 50 ft³ of mulch. See the dedicated mulch, soil and gravel calculators for material-specific bag and weight estimates.
Concrete & Flooring
Slabs: floor area × slab thickness. Insulation: floor area × insulation thickness. Both produce cubic feet of material to order — see the concrete calculator for slab-specific bag counts and waste factors.
Excavation
Dig area × dig depth = cubic feet of soil removed. Order replacement fill in cubic yards (÷27), adding 15% for compaction — the fill dirt calculator builds this compaction factor in automatically.
Worked Examples
Driveway gravel: 400 sq ft × 4 in (0.333 ft) = 133 ft³ ÷ 27 = 4.93 yd³.
Lawn topsoil: 1,500 sq ft × 2 in (0.167 ft) = 250 ft³ = 9.26 yd³.
Insulation in attic: 1,200 sq ft × 10 in (0.833 ft) = 1,000 ft³.
Frequently Asked Questions
How do I convert square feet to cubic feet?
Multiply square feet by the depth in feet. Area × depth = volume.
What does 'square feet to cubic feet' actually mean?
Square feet measure area (a 2D surface). To make it a 3D volume in cubic feet, multiply by a thickness or depth in feet.
How many cubic feet is 100 square feet?
It depends on depth. 100 sq ft × 6 inches (0.5 ft) = 50 ft³. 100 sq ft × 12 inches (1 ft) = 100 ft³.
How do I convert square feet to cubic yards?
Multiply sq ft × depth in feet, then divide by 27. 200 sq ft × 4 in (0.333 ft) = 66.7 ft³ ÷ 27 = 2.47 yd³.
What depth do I use for landscaping?
Mulch: 2–4 inches. Topsoil for lawn: 2–4 inches. Garden beds: 6–12 inches. Driveway gravel: 4–6 inches.
Can I add square feet directly to cubic feet?
No. They measure different things (area vs volume). You must multiply square feet by a depth to get cubic feet.
How do I calculate cubic feet for a concrete slab?
Slab area in square feet × thickness in feet = cubic feet. A 100 sq ft slab × 4 in (0.333 ft) = 33.3 ft³.
How do I convert depth in inches to feet?
Divide inches by 12. 3 in = 0.25 ft; 4 in = 0.333 ft; 6 in = 0.5 ft; 12 in = 1 ft.