How to Calculate Board Feet to Linear Feet
Use this premium lumber calculator to convert board feet into linear feet based on thickness and width. Perfect for trim, hardwood, rough lumber, decking prep, cabinet stock estimates, and jobsite ordering.
Board Feet to Linear Feet Calculator
Enter the total board feet and the board dimensions in inches. The calculator uses the standard lumber formula: linear feet = (board feet × 12) ÷ (thickness × width).
Linear Feet by Common Width
The chart shows how many linear feet your entered board feet would produce at the selected thickness across several common widths.
Expert Guide: How to Calculate Board Feet to Linear Feet
Understanding how to convert board feet to linear feet is one of the most practical lumber skills for homeowners, woodworkers, trim carpenters, cabinet builders, and contractors. The confusion usually comes from the fact that board feet and linear feet measure different things. A board foot measures volume. A linear foot measures length. To move from one to the other, you need the missing dimensions of the board, specifically its thickness and width. Once those are known, converting board feet to linear feet is straightforward.
If you remember only one formula, remember this one: linear feet = (board feet × 12) ÷ (thickness in inches × width in inches). This formula works because one board foot equals 144 cubic inches, or a board that is 12 inches long, 12 inches wide, and 1 inch thick. When thickness and width are already known, dividing the cubic volume by the cross sectional area gives you the total length, which is then expressed in feet.
What Is a Board Foot?
A board foot is a unit of wood volume commonly used for hardwood lumber, rough sawn stock, specialty millwork stock, and some sawmill transactions in the United States. One board foot equals a piece of wood that is:
- 12 inches long
- 12 inches wide
- 1 inch thick
That is equal to 144 cubic inches. Board feet are useful because they let buyers compare lumber volume even when boards have different widths and lengths.
What Is a Linear Foot?
A linear foot measures only length. If a trim board is 8 feet long, that is 8 linear feet, regardless of whether it is narrow or wide. Linear feet are commonly used for molding, baseboard, fencing, decking edges, handrails, and other products where the installed length matters most.
The challenge is that linear feet alone do not tell you the total wood volume. A 10 foot board that is 4 inches wide uses much less wood than a 10 foot board that is 12 inches wide. That is why converting board feet to linear feet always requires width and thickness.
The Exact Formula for Board Feet to Linear Feet
The standard board foot formula is:
Board feet = (thickness in inches × width in inches × length in feet) ÷ 12
To solve for length in feet, rearrange the formula:
Linear feet = (board feet × 12) ÷ (thickness in inches × width in inches)
That is the formula used in the calculator above. It works for rough and surfaced lumber as long as you enter the dimensions you actually want to use for estimating. For buying hardwood, many shops estimate from actual measured thickness and actual width. For softwood framing and home center material, many buyers think in nominal sizes, but the true dressed dimensions are smaller, so using actual dimensions will usually produce more accurate purchasing numbers.
Step by Step Example
- Start with your total board feet. Example: 100 board feet.
- Determine thickness in inches. Example: 1.5 inches.
- Determine width in inches. Example: 5.5 inches.
- Multiply board feet by 12. Example: 100 × 12 = 1200.
- Multiply thickness by width. Example: 1.5 × 5.5 = 8.25.
- Divide 1200 by 8.25.
- Result: 145.45 linear feet.
This means 100 board feet of stock that is 1.5 inches thick and 5.5 inches wide equals about 145.45 linear feet of material.
Why Nominal and Actual Dimensions Matter
One of the biggest estimating mistakes is confusing nominal lumber sizes with actual sizes. In the United States, a board sold as 2×6 is not usually 2 inches thick and 6 inches wide after surfacing and drying. A typical surfaced dry 2×6 measures about 1.5 inches by 5.5 inches. That difference matters in a conversion formula because thickness and width appear in the denominator. Even small dimensional changes can noticeably affect the resulting linear footage.
| Nominal size | Typical actual size in inches | Board feet in one 8 foot piece | Linear feet per board foot |
|---|---|---|---|
| 1×4 | 0.75 × 3.5 | 1.75 | 4.57 |
| 1×6 | 0.75 × 5.5 | 2.75 | 2.91 |
| 1×8 | 0.75 × 7.25 | 3.63 | 2.20 |
| 2×4 | 1.5 × 3.5 | 3.50 | 2.29 |
| 2×6 | 1.5 × 5.5 | 5.50 | 1.45 |
| 2×8 | 1.5 × 7.25 | 7.25 | 1.10 |
The values above illustrate a simple truth: wider and thicker boards consume board footage faster. A 1×4 gives you much more linear length per board foot than a 2×8.
Common Use Cases
Converting board feet to linear feet is especially useful in these scenarios:
- Trim and molding jobs: You may know the total board footage available from a supplier and need to estimate how many feet of casing or base you can cut.
- Hardwood purchasing: Hardwood dealers often sell by the board foot, but projects such as face frames, slat walls, edge trim, and battens are planned by length.
- Sawmill output planning: If you mill a log into boards of one thickness and width, converting volume to length helps you stage inventory.
- Cost comparisons: You can compare the effective cost per linear foot when the seller prices wood by board foot.
Conversion Table: 100 Board Feet to Linear Feet
The next table shows how 100 board feet converts into linear feet at several common thickness and width combinations. These are calculated values based on the standard formula.
| Thickness | Width | Cross section area | Linear feet from 100 board feet |
|---|---|---|---|
| 3/4 inch | 3.5 inches | 2.625 sq in | 457.14 ft |
| 3/4 inch | 5.5 inches | 4.125 sq in | 290.91 ft |
| 1 inch | 6 inches | 6 sq in | 200.00 ft |
| 1.5 inches | 3.5 inches | 5.25 sq in | 228.57 ft |
| 1.5 inches | 5.5 inches | 8.25 sq in | 145.45 ft |
| 1.5 inches | 7.25 inches | 10.875 sq in | 110.34 ft |
| 2 inches | 8 inches | 16 sq in | 75.00 ft |
How to Avoid Estimating Errors
Even experienced builders make mistakes when switching between board feet and linear feet. The most common issues are easy to prevent if you use a repeatable process.
- Use consistent dimensions. Do not mix nominal and actual measurements in the same estimate.
- Keep dimensions in inches. Thickness and width should be entered in inches when using the standard formula shown here.
- Check moisture and surfacing assumptions. Rough lumber dimensions can differ from surfaced dry lumber dimensions.
- Add waste where needed. Defects, trimming, knots, milling losses, and layout cuts can all reduce usable length.
- Separate project parts. If your job uses multiple widths or thicknesses, calculate each group independently.
Board Feet vs Linear Feet vs Square Feet
These three measurements are related, but they are not interchangeable:
- Board feet measure volume.
- Linear feet measure length.
- Square feet measure area.
For example, flooring and paneling are often estimated in square feet because coverage matters. Trim is often estimated in linear feet because installed run matters. Hardwood stock is often bought in board feet because total wood volume matters. Knowing which unit applies to your project can save significant time and money.
When to Use Actual Dimensions
Actual dimensions are usually best when accuracy matters. If you are building cabinetry, furniture, custom millwork, or ordering surfaced lumber, use the true measured thickness and width. This is also the safer choice if you are comparing suppliers, because actual dimensions can vary slightly by milling process. The more exact your inputs, the more reliable your conversion from board feet to linear feet will be.
Professional Estimating Tip
On larger jobs, convert your order into both board feet and linear feet. Board feet helps with purchasing and cost control. Linear feet helps with layout and installation planning. When you track both numbers, you can quickly see whether a material shortage is due to defects, bad cuts, or simply using a wider profile than expected.
Authoritative References
For deeper technical reading on wood properties, lumber dimensions, and measurement standards, review these authoritative sources:
- USDA Forest Service: Wood Handbook
- National Institute of Standards and Technology: Unit Conversion Resources
- University Cooperative Extension Wood Products Resources
Final Takeaway
To calculate board feet to linear feet, you need three pieces of information: total board feet, thickness in inches, and width in inches. Apply the formula (board feet × 12) ÷ (thickness × width), and you will get the total linear feet. This conversion is essential whenever lumber is bought by volume but used by length. With the calculator on this page, you can get the answer instantly, compare widths visually on the chart, and make faster material decisions for your next project.