Calculate linear footage
Enter lumber volume and actual board dimensions. The result appears above this form after calculation.
Example conversion data
These examples use actual dimensions in inches and do not include waste.
| Board feet | Thickness | Width | Linear feet |
|---|---|---|---|
| 12 BF | 1 in | 6 in | 24 ft |
| 50 BF | 2 in | 4 in | 75 ft |
| 100 BF | 1.5 in | 5.5 in | 145.45 ft |
| 120 BF | 2 in | 6 in | 120 ft |
Formula used
The calculation uses dimensions in inches. Millimetres are converted to inches first.
Linear feet = (Board feet × 12) ÷ (Thickness × Width)
Adjusted board feet = Board feet × (1 + Waste percentage ÷ 100)
Adjusted linear feet = Base linear feet × (1 + Waste percentage ÷ 100)
Thickness and width describe the board cross-section. A larger cross-section produces fewer linear feet from the same board footage.
How to use this calculator
- Enter the total board feet from your estimate, stock list, or supplier quote.
- Enter the actual thickness and width. Select inches or millimetres for each measurement.
- Add a waste allowance. Use zero only when you need the exact theoretical conversion.
- Optionally enter stock length to estimate full boards and expected surplus.
- Choose display precision, then select Calculate Linear Footage. Download the result as CSV or PDF when needed.
Lumber planning essentials
Understanding both measurements
Board foot and linear foot measure different lumber properties. A board foot measures volume. A linear foot measures length. You need the board width and thickness before converting volume into length.
A standard board foot equals 144 cubic inches. It describes a piece one inch thick, twelve inches wide, and twelve inches long. Lumber sizes can vary. Actual dimensions may differ from nominal labels. Use actual measurements when accuracy matters.
Applying the core formula
The conversion begins with cross-sectional area. Multiply thickness by width in inches. This gives square inches. Divide twelve by that area. Then multiply by the board feet. The result is linear feet before waste.
For example, suppose you have 120 board feet. Your boards are two inches thick and six inches wide. The cross-section is twelve square inches. Multiply 120 by twelve. Divide by twelve. You need 120 linear feet. A thinner or narrower board produces more linear feet from the same volume.
Allowing for real-world waste
Waste changes purchasing needs. Cuts, defects, grain matching, and layout adjustments can consume material. A five percent waste allowance multiplies the original board footage by 1.05. The calculator converts that adjusted volume into required linear footage. Use a larger allowance for complex work.
Stock length helps with ordering. Boards are sold in set lengths. Enter the available board length in feet. The calculator estimates how many boards are needed. It rounds upward because partial boards still require purchase. This estimate does not replace a cutting plan.
Checking units and results
Units deserve attention. Thickness and width can be entered in inches or millimetres. The calculator converts millimetres to inches before applying the formula. Keep measurements realistic. A zero or negative dimension has no physical meaning. Check dimensions before trusting an estimate.
Results include base linear feet and waste-adjusted linear feet. When a stock length is provided, they also include board count, purchased linear feet, purchased board feet, and expected surplus. These values help compare suppliers and available stock.
Making better purchasing decisions
Use the base result for design discussions. Use the adjusted result for purchasing. Confirm whether the supplier uses nominal or actual dimensions. Also confirm available lengths. A supplier may round dimensions differently for surfaced lumber. Ask about defects and grading when material quality matters.
This calculator supports planning, estimates, and inventory checks. It does not account for kerf, joinery, tapering, curved cuts, moisture movement, or machining losses individually. Add an appropriate waste amount when those factors matter. Measure twice before finalizing a lumber order.
Comparing lumber choices
Consider board orientation during planning. The same volume can be supplied as many narrow boards or fewer wide boards. This changes the linear footage, handling time, visual appearance, and cutting efficiency. Match width and thickness to structural needs before comparing prices. Do not compare price per linear foot alone. Board-foot pricing is better for volume comparisons, while linear-foot pricing is useful when dimensions are already fixed. Record assumptions beside each estimate. They make later revisions faster and clearer.
Frequently asked questions
What is a board foot?
A board foot is a lumber volume equal to 144 cubic inches. It is commonly calculated from thickness, width, and length. It does not describe a fixed board length.
What is a linear foot?
A linear foot is twelve inches of length. It ignores width and thickness. Therefore, it becomes meaningful for lumber only after the board cross-section is known.
What formula converts board feet to linear feet?
Linear feet equal board feet multiplied by twelve, divided by thickness times width. Thickness and width must be in inches. The formula calculates length from lumber volume.
Should I use nominal or actual lumber dimensions?
Use actual dimensions for the best estimate. Nominal sizes can differ after surfacing. For example, a labelled two-by-six may not measure exactly two inches by six inches.
Can I enter millimetres?
Yes. Select millimetres for thickness or width when needed. The calculator changes each measurement into inches before applying the board-foot formula.
Why add a waste allowance?
Waste covers cuts, defects, layout changes, grain matching, and small mistakes. A practical allowance helps avoid an extra purchase during the project.
How does stock length affect the result?
Stock length does not change required linear footage. It helps estimate how many full boards to buy. The calculator rounds the number upward to a whole board.
Why is purchased footage larger than required footage?
Available boards come in fixed lengths. Rounding to whole boards can create surplus. The result shows that expected extra material so you can plan for offcuts.
Does this work for hardwood and softwood?
Yes. The volume relationship is the same for both. Still, purchase rules, actual dimensions, grading, and available lengths can vary by supplier.
Can I use this for plywood?
It can estimate equivalent length for rectangular strips of a fixed thickness and width. Full plywood sheets are normally planned by area and sheet size instead.
Does it create a cutting list?
No. It estimates material quantity. A cutting list needs individual part sizes, kerf, trim allowances, defects, and grain direction. Use this result as a starting point.