Cubic Feet Calculator
Calculate volume in cubic feet for any shape — box, cylinder, sphere, cone, or triangular prism. Convert to cubic yards, cubic meters, gallons, and liters. Supports feet, inches, centimeters, and meters.
📦 Cubic Feet Calculator
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💡 How to Calculate Cubic Feet
What Is a Cubic Foot?
A cubic foot (symbol: ft³ or cu ft) is a unit of volume in the US customary and imperial measurement systems. One cubic foot equals the volume of a cube with edges exactly one foot (12 inches) long. To put it in perspective, a cubic foot is roughly the size of a standard file storage box or a basketball.
The cubic foot is the primary volume unit used in the United States for:
Convert to cubic yards with our cubic yards calculator. Measure area with our square footage calculator. For tank volumes, see our tank volume calculator.
- Construction — ordering concrete, gravel, mulch, topsoil, and sand
- Moving and storage — measuring truck capacity and box sizes
- HVAC — airflow rated in CFM (cubic feet per minute)
- Shipping — calculating dimensional weight for freight
- Appliances — refrigerator, freezer, oven, and dishwasher capacity
Cubic Feet Formula for Common Shapes
Different shapes require different formulas. Use all measurements in feet for results in cubic feet:
| Shape | Formula | Example |
|---|---|---|
| Rectangle / Box | L × W × H | 10 × 8 × 4 = 320 cu ft |
| Cube | Side³ | 5³ = 125 cu ft |
| Cylinder | π × r² × H | π × 2² × 6 = 75.4 cu ft |
| Sphere | (4/3) × π × r³ | (4/3) × π × 3³ = 113.1 cu ft |
| Cone | (1/3) × π × r² × H | (1/3) × π × 2² × 6 = 25.1 cu ft |
| Triangular Prism | ½ × B × H × L | ½ × 4 × 3 × 10 = 60 cu ft |
Cubic Feet Conversion Table
Use these exact conversion factors to convert cubic feet to other volume units:
| From 1 Cubic Foot | To | Multiply By |
|---|---|---|
| 1 cu ft | Cubic Inches | 1,728 |
| 1 cu ft | Cubic Yards | 0.037037 |
| 1 cu ft | Cubic Meters | 0.0283168 |
| 1 cu ft | US Gallons | 7.48052 |
| 1 cu ft | Liters | 28.3168 |
| 1 cu ft | Quarts | 29.922 |
| 27 cu ft | 1 Cubic Yard | — |
Note: Cubic feet and square feet do not directly convert — square feet measures area (2D) while cubic feet measures volume (3D). To go from square feet to cubic feet, multiply the area by the height or depth in feet.
When to Use Cubic Feet
Moving and Storage
Moving companies in the US price estimates by total cubic feet of belongings. Knowing your cubic footage helps you choose the right truck size and get accurate quotes. Standard US moving box sizes:
- Small box (16" × 12" × 12") = 1.33 cu ft
- Medium box (18" × 18" × 16") = 3.0 cu ft
- Large box (24" × 18" × 18") = 4.5 cu ft
- Extra-large box (24" × 20" × 24") = 6.67 cu ft
Popular truck sizes: 10-ft truck = 402 cu ft, 15-ft truck = 764 cu ft, 20-ft truck = 1,015 cu ft, 26-ft truck = 1,611 cu ft. A typical one-bedroom apartment requires 350–500 cu ft of truck space.
Landscaping Materials
Mulch, topsoil, gravel, and sand are sold by the cubic foot (bags) or cubic yard (bulk). To calculate cubic feet for a garden bed: measure the area in square feet, decide on the depth (usually 2–4 inches for mulch), convert depth to feet (divide by 12), and multiply: Area × Depth = Cubic Feet.
Worked example: A 20 × 8 ft flower bed with 3 inches of mulch: 20 × 8 = 160 sq ft × (3 ÷ 12) = 160 × 0.25 = 40 cubic feet. That's 20 bags of 2 cu ft mulch, or about 1.5 cubic yards for a bulk delivery. Always order 5–10% extra for settling and uneven areas.
HVAC and Airflow
HVAC professionals size heating and cooling systems using the room's cubic footage. Multiply length × width × ceiling height to get the room volume in cubic feet. General guidelines:
- Air conditioners: approximately 20–25 BTU per cubic foot
- Heaters: 30–35 BTU per cubic foot in cold climates (zones 5–7)
- Ventilation: most rooms need the air exchanged 4–6 times per hour — so a 1,200 cu ft room needs a fan rated at 80–120 CFM
Shipping and Freight
Freight carriers calculate dimensional weight using cubic feet. The formula: (Length × Width × Height in inches) ÷ the carrier's DIM factor (usually 139 for domestic US shipments). If the dimensional weight exceeds the actual weight, you pay for the dimensional weight. Calculating cubic feet first helps you estimate whether you'll be charged by actual or dimensional weight.
Appliance Capacity
In the US, refrigerator and freezer capacity is measured in cubic feet. Common sizes: side-by-side refrigerators = 22–28 cu ft, French door = 20–30 cu ft, top-freezer = 15–22 cu ft, chest freezer = 5–25 cu ft. When shopping for appliances, knowing the cubic footage helps compare capacity across brands and styles.
How to Calculate Cubic Feet from Other Units
If your measurements are not in feet, convert them first:
- From inches: divide each measurement by 12, then multiply L × W × H. Or multiply L × W × H in inches, then divide the result by 1,728.
- From yards: multiply each measurement by 3, then calculate. Or multiply the result in cubic yards by 27.
- From centimeters: divide each measurement by 30.48, then calculate. Or divide the result in cubic centimeters by 28,316.85.
- From meters: multiply each measurement by 3.28084, then calculate. Or multiply the result in cubic meters by 35.3147.
Pro Tips for Accurate Volume Calculations
- Always order 5–10% extra material for construction projects — dimensions are never perfect, and some material is lost to spillage and waste.
- Compaction factor: loose materials (gravel, soil) compact 20–30% when settled or compacted, so order accordingly.
- Don't confuse cubic feet with square feet. Square feet (sq ft) measures flat area. Cubic feet (cu ft) measures volume. You need a third dimension (depth/height) to convert between them.
- For irregular shapes: break the area into simpler shapes (rectangles, cylinders), calculate each volume separately, and add them together.
- A cord of firewood = 128 cubic feet (8 ft × 4 ft × 4 ft). A face cord = about 43 cubic feet.