Cubic Feet Calculator for Wood: How to Use It

A cubic feet calculator for wood works out the volume of a wood log, board, or stack in cubic feet (ft³) from its length, width, and thickness. You enter three dimensions in inches or feet, and the calculator returns the volume in cubic feet, plus often board feet or cubic meters for comparison. This is the standard way to estimate how much wood you have for lumber, firewood, or shipping.

Formula

The basic formula for the volume of a rectangular piece of wood is:

Volume (ft³) = (Length × Width × Thickness) ÷ 1728

Where:

• Length is in inches (in)
• Width is in inches (in)
• Thickness is in inches (in)
• 1728 is the number of cubic inches in one cubic foot (12 × 12 × 12)

If you measure in feet, the formula is simply Length × Width × Thickness, all in feet. The calculator above uses inches because that is how most lumber is sold and measured.

Worked Example

Using the default values from the calculator: a board 96 inches long, 6 inches wide, and 2 inches thick.

1. Multiply the dimensions in inches: 96 × 6 × 2 = 1152 cubic inches.
2. Divide by 1728 (cubic inches per cubic foot): 1152 ÷ 1728 = 0.667 cubic feet.
3. For board feet: 1152 ÷ 144 = 8 board feet.
4. For cubic meters: 1152 ÷ 61023.7 = 0.0189 m³.

The calculator shows 0.667 ft³, 8.00 bd ft, and 0.0189 m³ for the defaults.

Why Use Cubic Feet for Wood?

Cubic feet is a direct measure of volume, so it tells you how much space the wood occupies. That matters for:

• Shipping and storage – truck or container capacity is often given in cubic feet.
• Firewood – sold by the cord, which is 128 cubic feet (including air gaps).
• Log scaling – estimating the usable lumber inside a log before milling.
• Comparing different sizes – a 2×4 and a 2×6 may have the same length but different volumes.

Board feet, on the other hand, is a lumber-industry unit that ignores thickness variations in a specific way. One board foot is 1 inch thick × 12 inches wide × 12 inches long. For a piece that is already 1 inch thick, board feet equals the surface area in square feet. For thicker pieces, multiply by the thickness in inches.

How to Measure Wood for the Calculator

Accurate input is essential. Follow these steps:

1. Measure the length along the grain, from end to end, in inches or feet.
2. Measure the width across the face, perpendicular to the grain.
3. Measure the thickness (or height) – the smallest dimension.
4. For a stack of wood, measure the overall height, width, and depth of the stack, then subtract air gaps if you need solid wood volume.

For logs that are round, use the average diameter (measured inside the bark) and the length. The formula for a cylinder is π × (diameter/2)² × length, then convert to cubic feet. The calculator above assumes a rectangular piece, so for a log you would need a different tool or a manual calculation.

Common Mistakes and How to Avoid Them

• Mixing units – do not enter length in feet and width in inches. Convert everything to the same unit first.
• Forgetting the 1728 factor – many people divide by 12 instead of 1728, which gives a result 144 times too large.
• Using nominal vs. actual dimensions – a “2×4â€� is actually 1.5 × 3.5 inches after planing. Use actual measurements for accurate volume.
• Ignoring air gaps in firewood – a cord is 128 cubic feet of space, but the solid wood volume is less, typically 80–100 cubic feet depending on how it is stacked.
• Rounding too early – round only at the final step to avoid small errors that can become large when scaling up.

Limits of the Cubic Feet Formula

The simple length × width × thickness formula assumes a perfect rectangular prism. Real wood is never perfectly uniform:

• Logs taper – the diameter changes along the length.
• Boards may have wane (missing corners) or irregular edges.
• Moisture content affects volume – wood shrinks as it dries.

For rough estimates, the rectangular formula is fine. For precise log volume, foresters use formulas like the Doyle or Scribner log rules, which account for taper and saw kerf. For firewood, the cord is a legal unit in many places, so check local regulations.

Related Units and Conversions

Wood volume is expressed in several units depending on the context. Here are the key conversions:

• 1 cubic foot = 1728 cubic inches = 0.0283168 cubic meters
• 1 board foot = 144 cubic inches = 1/12 cubic foot
• 1 cord = 128 cubic feet (stacked firewood)
• 1 cubic meter = 35.3147 cubic feet

If you buy lumber from a sawmill, they may quote board feet. If you ship wood, the carrier likely charges by cubic feet or cubic meters. Knowing both helps you compare prices fairly.

Frequently Asked Questions

How many cubic feet is a standard 2×4×8?

A nominal 2×4 that is 8 feet long has actual dimensions of 1.5 × 3.5 × 96 inches. Volume = 1.5 × 3.5 × 96 = 504 cubic inches, divided by 1728 = 0.2917 cubic feet. In board feet, it is 504 ÷ 144 = 3.5 board feet.

What is the difference between cubic feet and board feet?

Cubic feet is a pure volume measure (length × width × thickness in feet). Board feet is a lumber-industry unit equal to 1 inch × 12 inches × 12 inches. A board that is 1 inch thick has the same number of board feet as its square footage. For thicker boards, board feet = (thickness in inches) × (surface area in square feet).

How do I calculate cubic feet of a round log?

Measure the diameter inside the bark at the small end (or average of both ends) and the length. Use the cylinder formula: π × (diameter/2)² × length, all in feet. For example, a log 10 feet long with a 1-foot diameter gives 3.1416 × 0.5² × 10 = 7.85 cubic feet. This is the geometric volume; usable lumber will be less due to saw kerf and defects.

How many cubic feet are in a cord of firewood?

A cord is defined as 128 cubic feet of tightly stacked wood, including air spaces. The actual solid wood volume is typically 80–100 cubic feet depending on how straight and uniform the pieces are. When buying firewood, always confirm whether the price is per cord, per face cord (1/3 cord), or per cubic foot.

Does the calculator work for green (wet) wood?

It calculates the physical volume of the piece as measured. Green wood contains water, so its weight is higher, but the volume is the same as dry wood at the same dimensions. However, wood shrinks as it dries – typically 3–8% in width and thickness. If you measure green wood and then dry it, the volume will decrease slightly.

Can I use this for plywood or engineered wood?

Yes, the formula works for any rectangular solid, including plywood, MDF, or particleboard. Just measure the actual thickness (e.g., 0.75 inches for 3/4-inch plywood) and the length and width. The volume in cubic feet is useful for estimating shipping weight or storage space.

Related

• Bedrock Seed Calculator: Find Your World’s Seed
• Bastion Concrete Calculator: Mix & Volume Guide
• Building Square Footage Calculator: How to Measure

in length | Length | in | 96 | 0
in width | Width | in | 6 | 0
in thickness | Thickness | in | 2 | 0
out cubic_ft | Cubic feet | ft³ | (length * width * thickness) / 1728 | 3
out board_ft | Board feet | bd ft | (length * width * thickness) / 144 | 2
out cubic_m | Cubic meters | m³ | (length * width * thickness) / 61023.7 | 4