How do you calculate cubic feet?

To calculate cubic feet, measure your object's length, width, and height in feet, and multiply them together (Length × Width × Height). If your measurements are in inches, multiply them together to get cubic inches, then divide the total by 1,728 to convert to cubic feet.

Is 1 cubic foot 12x12x12?

Yes, a volume that is 12 inches long, 12 inches wide, and 12 inches high equals exactly 1 cubic foot. 12 x 12 x 12 equals 1,728 cubic inches, which is the exact definition of a cubic foot.

What size is 1 cubic ft?

One cubic foot is the volume of a perfect cube where every side measures exactly 1 foot (or 12 inches) in length. It occupies the same physical space as roughly 7.48 US liquid gallons.

How to calculate 1 cft of wood?

One cubic foot (cft) of wood contains exactly 12 board feet. To calculate if you have 1 cft of wood, measure the piece in inches, multiply Length × Width × Thickness, and if the result is 1,728 cubic inches, you have 1 cubic foot of wood.

What is 1 cubic foot of wood?

One cubic foot of wood is a solid block of timber measuring exactly 12 inches by 12 inches by 12 inches. In the lumber industry, this is equivalent to exactly 12 board feet (since one board foot is 144 cubic inches).

How many board feet are in a 2x4x10 wood?

A standard 2x4 that is 10 feet long contains 6.67 board feet. The formula is (Thickness in inches × Width in inches × Length in feet) ÷ 12. So, (2 × 4 × 10) ÷ 12 = 6.667 board feet.

How many board feet are in a 2x4x8 ft?

A standard 2x4 that is 8 feet long contains 5.33 board feet. Using the board foot formula: (2 inches × 4 inches × 8 feet) ÷ 12 = 5.33 board feet.

Is 4/4 lumber actually 1 inch?

Nominally, yes. 4/4 (four-quarters) lumber means the board was roughly cut to 1 inch thick at the sawmill. However, after drying and surfacing (planing) to make it smooth, a finished 4/4 board is typically about 13/16 or 3/4 of an inch thick.

How many board ft is in a 1x12x12?

A 1x12 board that is 12 feet long contains exactly 12 board feet. Calculation: (1 inch thick × 12 inches wide × 12 feet long) ÷ 12 = 12 board feet. Coincidentally, 12 board feet is also exactly equal to 1 cubic foot.

Cubic Feet Calculator | Calculate Volume (cu ft) Instantly

Cubic Feet Calculator

Instantly calculate cubic feet (cu ft) for any rectangular solid or cylinder. Enter your measurements below in inches, feet, yards, or meters to accurately determine total volume.

1. Select Object Shape

Rectangular / Box Cylinder / Tube

2. Enter Dimensions

Length

Width

Height / Depth

3. Optional Options

Quantity Number of items this size

Total Volume

125 Cubic Feet (ft³)

5 ft × 5 ft × 5 ft

Cubic Yards (yd³) 4.63

Cubic Meters (m³) 3.54

Cubic Inches (in³) 216,000

Knowing exactly how to calculate cubic feet is a fundamental skill whether you are estimating topsoil for a landscaping project, measuring a room for HVAC sizing, calculating freight shipping volume, or figuring out how much lumber you need. A cubic foot is simply a measure of three-dimensional volume.

By definition, one cubic foot is the volume occupied by a cube that is exactly 1 foot long, 1 foot wide, and 1 foot high. Because not everything is measured perfectly in feet, our cubic feet calculator lets you input dimensions in inches, yards, centimeters, or meters, and handles all the complex volume conversions automatically.

Table of Contents

How to Calculate Cubic Feet (The Formula)

To find the volume of any object or space in cubic feet, you must multiply its three primary dimensions: length, width, and height. However, the most common mistake people make is failing to ensure all three measurements are in feet before they multiply them together.

1. For Rectangular Solids (Boxes, Rooms, Planters)

This is the standard formula used for shipping boxes, raised garden beds, and square rooms.

Cubic Feet Formula (Rectangular)

Cubic Feet (ft³) = Length (ft) × Width (ft) × Height (ft)

If your measurements are in inches, you must divide the final result by 1,728 to convert back to cubic feet.

2. For Cylinders (Tanks, Columns, Round Pots)

If you are trying to fill a circular fire pit with gravel or a round tank with water, you need the cylindrical volume formula.

Cubic Feet Formula (Cylindrical)

Volume = π × r² × Height

π (Pi) ≈ 3.14159
r (Radius) = Half of the diameter across the circle (in feet)
Height = Depth or height of the cylinder (in feet)

Step-by-Step Calculation Examples

Example 1: Measuring in Feet

Let’s say you are filling a raised garden bed that is 8 feet long, 4 feet wide, and 2 feet deep.

Formula: L × W × H
Math: 8 × 4 × 2
Result: 64 cubic feet of soil required.

Example 2: Measuring in Inches

You have a shipping box that measures 24 inches long, 18 inches wide, and 12 inches high. How many cubic feet is this?

Step 1 (Multiply in inches): 24 × 18 × 12 = 5,184 cubic inches.
Step 2 (Convert to feet): Because there are 1,728 cubic inches in one cubic foot (12″ x 12″ x 12″), you divide your total by 1,728.
Math: 5,184 ÷ 1,728 = 3.0 cubic feet.

Converting Common Units to Cubic Feet

If you already know the volume of your object in a different metric, you don’t need to remeasure it. You can simply multiply or divide using standard conversion constants.

To Convert From…	Do This Math	Example
Cubic Inches (in³)	Divide by 1,728	3,456 in³ ÷ 1728 = 2.0 ft³
Cubic Yards (yd³)	Multiply by 27	2.0 yd³ × 27 = 54 ft³
Cubic Meters (m³)	Multiply by 35.3147	5 m³ × 35.3147 = 176.57 ft³
Liters (L)	Divide by 28.3168	100 L ÷ 28.3168 = 3.53 ft³

Wood & Lumber: Cubic Feet vs. Board Feet

One of the most frequent areas of confusion when calculating cubic feet involves buying lumber or woodworking materials. In the lumber industry, wood volume is rarely measured in cubic feet—it is measured in Board Feet (bd ft).

The Board Foot Rule

A board foot is a specialized volume measurement for lumber equal to 144 cubic inches. It represents a piece of wood that is theoretically 12 inches wide, 12 inches long, and 1 inch thick.

Because a standard cubic foot is 1,728 cubic inches, and a board foot is 144 cubic inches, it means that there are exactly 12 board feet in 1 cubic foot of wood (1728 ÷ 144 = 12).

How to Calculate Board Feet for a 2×4

Let’s calculate the board footage of a standard 2×4 stud that is 10 feet long.

Formula: (Thickness in inches × Width in inches × Length in feet) ÷ 12
Math: (2 × 4 × 10) ÷ 12
Result: 80 ÷ 12 = 6.67 board feet.

Note: When calculating board feet, you use the “nominal” size of the lumber (the 2×4), not the actual milled physical dimensions (which are closer to 1.5″ x 3.5″).

Common Conversion Mistakes

Assuming 1 cubic foot = 12 cubic inches: Because there are 12 inches in a foot, people often mistakenly assume there are 12 cubic inches in a cubic foot. Remember that volume is 3D. 12 × 12 × 12 = 1,728 cubic inches.
Mixing Units: Attempting to multiply a length measured in feet by a width measured in inches. Always convert all sides to the same unit before multiplying.
Confusing Cubic Feet with Square Feet: Square feet (sq ft) is a flat, 2D area (Length × Width). Cubic feet (cu ft) is 3D space (Length × Width × Height). You cannot convert square feet to cubic feet without knowing the height/depth.