Lumber Calculator
Estimate how many boards your project needs based on project length, board spacing, board size and waste allowance. You can also estimate total linear feet, board feet and project cost.
Project layout
Board dimensions
How to estimate lumber for a project
Start with the total length of the area where boards will be installed. Then divide that length by the planned spacing between boards or framing members.
Add one board to account for the starting edge or end member. This gives the basic quantity before waste.
Add a waste allowance for trimming, defects and unexpected cuts. A small project may need only a few percent, while more complex layouts may need a larger allowance.
The calculator also estimates total linear feet and board feet, which can help compare material quantities and costs.
Example calculation
Project length: 20 ft
Spacing: 16 in
Board length: 8 ft
Waste allowance: 10%
Frequently asked questions
What does board spacing mean?
Board spacing is the distance from one board or framing member to the next along the project length.
Why does the calculator add one board?
A layout usually needs a starting or ending board in addition to the intervals created by the spacing.
How much waste should I add?
Many projects use a waste allowance of around 5% to 15%, depending on cuts, defects and layout complexity.
Can I estimate lumber cost?
Yes. Enter a price per board and the calculator will estimate the total purchase cost.