How to Calculate Cubic Feet
With this cubic feet calculator, you'll quickly find out the volume of any box-shaped container in cubic feet. It may help you estimate the volume of a room, storage container, or the amount of material required for earthworks — for example, calculating cubic feet of soil, sand, or gravel. You can enter dimensions in any unit — feet, inches, yards, centimeters, or meters — and get instant results in all common volume units.
What Is a Cubic Foot?
One cubic foot is the volume that fills a 1 ft × 1 ft × 1 ft cube. It is the standard unit of volume used in the US customary and Imperial measurement systems. The symbol is ft³.
- 1 cubic foot = 1,728 cubic inches (in³)
- 1 cubic foot = 0.037037 cubic yards (yd³)
- 1 cubic foot = 0.028317 cubic meters (m³)
- 1 cubic foot = 28.3168 liters (L)
- 1 cubic foot = 7.48052 US gallons
The Cubic Feet Formula
The formula to calculate the volume of a rectangular box (cuboid) is:
Volume (ft³) = Length (ft) × Width (ft) × Height (ft)
If all three dimensions are already in feet, simply multiply them together. If your dimensions are in different units, convert them to feet first — or use the unit selectors above and let the calculator handle it for you.
How to Calculate Cubic Feet from Inches
If your measurements are in inches, you have two options:
Method 1 — Convert each dimension to feet first:
Divide each inch measurement by 12 to get feet, then multiply:
Length (ft) = Length (in) ÷ 12 Width (ft) = Width (in) ÷ 12 Height (ft) = Height (in) ÷ 12 Volume (ft³) = Length (ft) × Width (ft) × Height (ft)
Method 2 — Calculate volume in cubic inches, then convert:
Volume (in³) = Length (in) × Width (in) × Height (in) Volume (ft³) = Volume (in³) ÷ 1,728
Example: Box measuring 36 in × 24 in × 18 in
Length = 36 ÷ 12 = 3 ft Width = 24 ÷ 12 = 2 ft Height = 18 ÷ 12 = 1.5 ft Volume = 3 × 2 × 1.5 = 9 ft³
Unit Conversion Quick Reference
| From | To convert dimension to feet | To convert volume to ft³ |
|---|---|---|
| Inches (in) | Divide by 12 | Divide by 1,728 |
| Yards (yd) | Multiply by 3 | Multiply by 27 |
| Centimeters (cm) | Divide by 30.48 | Divide by 28,316.85 |
| Meters (m) | Multiply by 3.28084 | Multiply by 35.3147 |
Calculating Cubic Feet of Soil, Sand, or Gravel
One of the most common uses of this calculator is estimating how much fill material you need for a garden bed, sandbox, driveway, or landscaping project. Here's how to do it:
- Measure the length, width, and depth of the area you want to fill.
- Enter the values above and select the appropriate unit for each dimension.
- The result in cubic feet tells you exactly how much material you need.
- Optionally, enter the price per cubic foot (or yard/meter) to get the total material cost in your currency.
Tip: Bags of soil and mulch at garden centers typically show their volume in cubic feet on the label. Divide your total cubic feet by the bag size to find out how many bags to buy.
Measuring a Room or Irregular Space
For a rectangular room, measure the floor dimensions and the ceiling height. The cubic feet result tells you the volume of air in the room — useful for sizing HVAC systems, air purifiers, or humidifiers.
Frequently Asked Questions
- How many cubic feet is a 12×12 room?
- A 12 ft × 12 ft room with an 8 ft ceiling = 12 × 12 × 8 = 1,152 cubic feet.
- How do I convert cubic feet to cubic yards?
- Divide cubic feet by 27. For example, 54 ft³ = 54 ÷ 27 = 2 cubic yards.
- How do I convert cubic feet to liters?
- Multiply cubic feet by 28.3168. For example, 10 ft³ = 10 × 28.3168 = 283.17 liters.
- How do I convert cubic feet to gallons?
- Multiply cubic feet by 7.48052 for US gallons, or by 6.22884 for UK (Imperial) gallons.
- How many cubic feet in a cubic meter?
- 1 cubic meter = 35.3147 cubic feet.
- Can I use mixed units?
- Yes! Our calculator allows you to select a different unit for each dimension (Length, Width, Height) independently. This is useful when, for example, you know the length in feet and the height in inches.