Cubic Feet Calculator
What is a Cubic Foot?
A "Cubic Foot" (often written as $ft^3$ or cu ft) is a unit of volume in the Imperial and US Customary systems. It is defined as the volume of a cube where each side measures exactly one foot in length.
Picture a standard moving box that is 12 inches long, 12 inches wide, and 12 inches tall. That box represents exactly one cubic foot. This measurement is the standard for:
- Shipping: FedEx, UPS, and freight carriers charge by volume.
- Appliances: Refrigerator and freezer capacities are listed in cubic feet.
- Gardening: Bags of mulch or soil are sold by the cubic foot (e.g., a "2 cu ft bag").
- Construction: Concrete is often calculated in cubic feet before being converted to cubic yards.
The Calculation Formula
The math behind calculating cubic footage is simple, provided all your measurements are in the same unit. The formula for a rectangular object (a prism) is:
The Tricky Part: Unit Mismatches
The most common mistake people make is multiplying inches by feet. You cannot multiply 2 feet by 6 inches and get a correct result unless you convert them first.
Example: Calculating the volume of a box that is 2 feet long, 18 inches wide, and 1 foot high.
- Convert "18 inches" to feet: $18 \div 12 = 1.5$ feet.
- Now multiply: $2 \times 1.5 \times 1 = 3$ cubic feet.
Our calculator above handles this automatically, allowing you to mix and match units (meters, cm, yards) without doing any manual math.
Real World Examples
1. Refrigerator Capacities
If you are shopping for a fridge, "Cubic Feet" determines how much food fits inside.
- Small Apartment Fridge: 10–13 cu ft.
- Standard Family Fridge: 18–22 cu ft.
- Large French Door Fridge: 25–30+ cu ft.
2. Gardening & Landscape
Buying bagged mulch? A standard bag from Home Depot or Lowe's is usually 2 cubic feet. If you calculate that your garden bed needs 10 cubic feet of mulch, you simply buy 5 bags ($10 \div 2 = 5$).
3. Concrete Pouring
While small concrete jobs (like setting a fence post) use cubic feet, large driveways use Cubic Yards. There are 27 cubic feet in 1 cubic yard. Our calculator provides both results simultaneously so you can order the right amount from the mixer truck.
Common Conversion Cheat Sheet
If you need to do rough mental math, here are the conversion factors you should know:
| From | To | Math Operation |
|---|---|---|
| Cubic Inches ($in^3$) | Cubic Feet ($ft^3$) | Divide by 1,728 |
| Cubic Feet ($ft^3$) | Cubic Yards ($yd^3$) | Divide by 27 |
| Cubic Feet ($ft^3$) | Cubic Meters ($m^3$) | Divide by 35.315 |
| Cubic Feet ($ft^3$) | US Gallons | Multiply by 7.48 |
Freight carriers often use "Dimensional Weight" (Dim Weight). Even if your package is light, if it takes up 5 cubic feet of space, they may charge you as if it weighed 50 lbs! Always minimize the empty space in your boxes to save money.
More Measurement Tools
Ensure your measurements are precise with our other converters.
📦 Volume Converter 📏 Length Converter ⬜ Area Converter 🧱 Density Calculator