Cubic Feet Calculator
Cubic Feet Calculator: How to Calculate Cubic Footage for Any Shape or Application
Cubic feet (cu ft or ft³) is the standard unit of volume used in the US for measuring spaces, shipping containers, landscaping materials, appliances, and construction quantities. Whether you’re calculating how much mulch you need, figuring out a shipping rate, or sizing a concrete pour, understanding cubic footage is the key to getting the right amount of material.
What Is a Cubic Foot?
A cubic foot is a unit of volume equal to a cube that measures exactly 1 foot on all three sides — 1 ft × 1 ft × 1 ft. It contains 1,728 cubic inches, 7.48 gallons, or 0.0370 cubic yards.
The Cubic Feet Formula
For any rectangular or box-shaped space:
Cubic Feet = Length (ft) × Width (ft) × Height (ft)
All three dimensions must be in feet before multiplying. If your measurements are in inches, convert first — or use the shortcut below.
Calculating Cubic Feet from Inches
If your measurements are in inches:
Cubic Feet = (Length × Width × Height in inches) ÷ 1,728
Example: A box measuring 24″ × 18″ × 12″: (24 × 18 × 12) ÷ 1,728 = 5,184 ÷ 1,728 = 3 cubic feet
Calculating Cubic Feet from Centimeters
Cubic Feet = (L × W × H in cm) ÷ 28,316.8
Calculating Cubic Feet from Meters
Cubic Meters × 35.315 = Cubic Feet
Cubic Feet for a Cylinder
For round shapes — pipes, tanks, tree holes, cylinders:
Cubic Feet = π × Radius² × Height
Where radius = diameter ÷ 2, all in feet.
Example: A cylindrical planter 2 ft in diameter and 1.5 ft tall: Radius = 1 ft Cubic Feet = 3.14159 × 1² × 1.5 = 4.71 cubic feet
Is 12×12×12 a Cubic Foot?
Yes — exactly. A cube measuring 12 inches × 12 inches × 12 inches equals precisely 1 cubic foot, because 12 inches = 1 foot, and 1 ft × 1 ft × 1 ft = 1 cubic foot. This is the origin of “cubic foot” as a unit.
Cubic Feet to Cubic Yards Conversion
Cubic yards are used for large-scale landscaping and construction orders (concrete, topsoil, mulch). There are exactly 27 cubic feet in 1 cubic yard.
Cubic Yards = Cubic Feet ÷ 27
Cubic Feet = Cubic Yards × 27
| Cubic Feet | Cubic Yards |
|---|---|
| 27 cu ft | 1.0 cu yd |
| 54 cu ft | 2.0 cu yd |
| 81 cu ft | 3.0 cu yd |
| 135 cu ft | 5.0 cu yd |
| 270 cu ft | 10.0 cu yd |
Coverage Per Cubic Foot: Landscaping and Construction Applications
This is where cubic footage becomes most practical. Once you have your volume in cubic feet, you need to know how far it goes as a coverage material.
Landscaping Material Coverage by Depth
For materials like mulch, topsoil, sand, or gravel, coverage depends on how deeply you apply them.
| Depth Applied | Coverage per Cubic Foot | Coverage per Cubic Yard |
|---|---|---|
| 1 inch | 12 sq ft | 324 sq ft |
| 2 inches | 6 sq ft | 162 sq ft |
| 3 inches | 4 sq ft | 108 sq ft |
| 4 inches | 3 sq ft | 81 sq ft |
| 6 inches | 2 sq ft | 54 sq ft |
| 12 inches | 1 sq ft | 27 sq ft |
How much will 1 cubic foot cover? At 2 inches deep (standard mulch depth), 1 cubic foot covers 6 square feet. At 3 inches, it covers 4 square feet.
How many sq ft does 2 cubic feet cover? At 3-inch standard mulch or soil depth: 2 cu ft × 4 sq ft/cu ft = 8 square feet.
Calculating Square Feet to Cubic Feet
Cubic Feet = Square Feet × (Depth in Inches ÷ 12)
Example: 200 sq ft garden bed at 3 inches of mulch: 200 × (3 ÷ 12) = 200 × 0.25 = 50 cubic feet (1.85 cubic yards)
Cubic Feet by Application
Mulch Calculator
Mulch is typically applied at 2–3 inches for new beds and 1–2 inches for refreshing existing beds.
| Bed Area | 2″ deep | 3″ deep |
|---|---|---|
| 50 sq ft | 8.3 cu ft | 12.5 cu ft |
| 100 sq ft | 16.7 cu ft | 25 cu ft |
| 200 sq ft | 33.3 cu ft | 50 cu ft |
| 500 sq ft | 83.3 cu ft | 125 cu ft |
Mulch is sold in 2-cubic-foot bags at most retailers. For bulk orders, convert to cubic yards (÷ 27).
Topsoil and Soil Calculator
Topsoil is typically applied 4–6 inches deep for new beds or lawn repairs.
| Area | 4″ deep (cu ft) | 6″ deep (cu ft) | 6″ deep (cu yd) |
|---|---|---|---|
| 100 sq ft | 33.3 | 50 | 1.85 |
| 250 sq ft | 83.3 | 125 | 4.63 |
| 500 sq ft | 166.7 | 250 | 9.26 |
| 1,000 sq ft | 333.3 | 500 | 18.52 |
Concrete Cubic Feet Calculator
Concrete is poured at a specific thickness. Use this formula:
Cubic Feet = Length (ft) × Width (ft) × Thickness (ft) Cubic Yards = Cubic Feet ÷ 27
| Slab Size | 4″ thick (cu yd) | 6″ thick (cu yd) |
|---|---|---|
| 10×10 ft | 1.23 cu yd | 1.85 cu yd |
| 12×12 ft | 1.78 cu yd | 2.67 cu yd |
| 20×20 ft | 4.94 cu yd | 7.41 cu yd |
| 20×40 ft | 9.88 cu yd | 14.81 cu yd |
Cubic Feet for Shipping
For freight and shipping, cubic feet determines dimensional weight — carriers charge by whichever is greater between actual weight and dimensional (volumetric) weight.
Cubic Feet (shipping) = (L × W × H in inches) ÷ 1,728
For international shipping, cubic meters (CBM) is standard: CBM = Cubic Feet ÷ 35.315
A standard 20-foot shipping container holds approximately 1,172 cubic feet (33.2 CBM) of cargo. A 40-foot container holds approximately 2,390 cubic feet (67.7 CBM).
Dimensional Weight Formula (US Domestic Freight)
Dimensional Weight (lbs) = (L × W × H in inches) ÷ 139
If dimensional weight exceeds actual weight, you’re billed on dimensional weight.
Cubic Feet for Refrigerators and Appliances
Refrigerator cubic footage refers to the interior usable storage volume, not the exterior dimensions. A fridge labeled “22 cu ft” has 22 cubic feet of interior storage space.
Refrigerator Size Guide by Cubic Feet
| Refrigerator Type | Typical Cubic Feet | Best For |
|---|---|---|
| Mini / compact fridge | 1.7 – 4.5 cu ft | Dorms, offices, bars |
| Small apartment fridge | 7 – 14 cu ft | 1–2 person households |
| Standard refrigerator | 18 – 22 cu ft | Family of 2–4 |
| Large refrigerator | 23 – 28 cu ft | Family of 4–6 |
| Extra-large / French door | 28 – 36 cu ft | Large families |
To measure interior cubic footage: measure interior length × width × height in inches, multiply, then divide by 1,728.
Cubic Feet for Wood and Lumber
Lumber volume is measured in board feet, but cubic feet is used for firewood, raw timber, and log volumes.
Cubic Feet (log) = π × (Diameter in ft ÷ 2)² × Length in ft
A standard cord of firewood = 128 cubic feet of stacked wood (4 ft × 4 ft × 8 ft), though the actual solid wood volume is approximately 80–90 cubic feet due to air gaps between logs.
Unit Conversion Quick Reference
| From | To | Multiply By |
|---|---|---|
| Cubic inches | Cubic feet | ÷ 1,728 |
| Cubic feet | Cubic inches | × 1,728 |
| Cubic yards | Cubic feet | × 27 |
| Cubic feet | Cubic yards | ÷ 27 |
| Cubic meters | Cubic feet | × 35.315 |
| Cubic feet | Cubic meters | ÷ 35.315 |
| Cubic feet | Gallons | × 7.481 |
| Gallons | Cubic feet | ÷ 7.481 |
Frequently Asked Questions
How Do I Calculate Cubic Feet?
Measure the length, width, and height of the space or object in feet, then multiply all three together: Length × Width × Height = Cubic Feet. If measurements are in inches, multiply all three together and divide by 1,728. For cylinders, use: π × radius² × height.
Is 12×12×12 a Cubic Foot?
Yes. 12 inches × 12 inches × 12 inches = 1,728 cubic inches = exactly 1 cubic foot. A cubic foot is precisely a cube with 12-inch (1 foot) sides.
How Many Cubic Feet Is 3×3×3?
3 feet × 3 feet × 3 feet = 27 cubic feet — which is exactly 1 cubic yard. This is why there are 27 cubic feet in a cubic yard: a cube 3 feet on every side equals one cubic yard.
How Many Sq Ft Does 2 Cubic Feet Cover?
It depends on depth. At 3-inch depth (standard mulch): 2 cu ft × 4 sq ft per cu ft = 8 square feet. At 2-inch depth: 2 × 6 = 12 square feet. At 1 inch: 2 × 12 = 24 square feet.
How Many Cubic Feet Is 1 Sq Ft?
One square foot is a measure of area (flat surface), not volume. To convert to cubic feet, you need to multiply by a depth. One square foot at 1 foot deep = 1 cubic foot. One square foot at 3 inches (0.25 ft) deep = 0.25 cubic feet.
How Much Will 1 Cubic Foot Cover?
At 1-inch depth: 12 square feet. At 2 inches: 6 square feet. At 3 inches: 4 square feet. At 4 inches: 3 square feet. This applies to mulch, soil, sand, gravel, and any loose material — the formula is simply 12 ÷ depth in inches = square feet per cubic foot.
Quick Reference Summary
| Formula | Equation |
|---|---|
| Box (ft) | L × W × H |
| From inches | (L × W × H) ÷ 1,728 |
| Cylinder | π × r² × Height |
| To cubic yards | Cu ft ÷ 27 |
| To cubic meters | Cu ft ÷ 35.315 |
| Coverage at 2″ | Sq ft × 0.1667 = cu ft |
| Coverage at 3″ | Sq ft × 0.25 = cu ft |
| 1 cu ft at 2″ | Covers 6 sq ft |
| 1 cu yd | 27 cubic feet |
Use the cubic feet calculator above to enter your dimensions in any unit — feet, inches, yards, meters, or centimeters — and get instant cubic footage plus cubic yards conversion.