Use the billed dimensions
Enter the supplier's actual billed or measured thickness, width, and length. Rough nominal shortcuts are a starting point, not a promise of surfaced dimensions.
Tool Switcher: Board Foot
Project toolsTools
Rough lumber planning
Board Foot Calculator
Turn thickness, width, length, and quantity into board feet. Combine several board sizes, add a project-specific allowance, and estimate cost from your supplier's price per board foot.
- Multiple board sizes
- US and metric units
- Optional cost estimate
Lumber planning tool
Board Foot Calculator
Combine board sizes, check exact volume, and plan a lumber purchase.
Methodology
From board dimensions to board feet
Find cubic inches
Thickness in inches × width in inches × length in inches × quantity gives the lumber volume in cubic inches.
Divide by 144
One board foot equals 144 cubic inches, so the volume is divided by 144. Each row stays separate before the project totals are combined.
Add your planning allowance
The calculator starts at 0%. Increase the allowance only for your cut plan, defects, matching needs, and supplier guidance.
Worked example
One 1 × 6 board, 8 feet long
1 in × 6 in × 8 ft576 cubic inches
÷144 cubic inchesper board foot
=4 BFexact lumber volume
With a 10% planning allowance, the recommended amount is 4.4 BF. At $8 per board foot, the estimated material cost is $35.20.
Frequently asked questions
A second look at the estimate.
How do you calculate board feet?
Multiply thickness in inches by width in inches by length in feet, then divide by 12 and multiply by quantity. This is equivalent to dividing cubic inches by 144.
Should I use 4/4 or the finished thickness?
Use the dimension on which your supplier bills the lumber. A 4/4 shortcut represents 1 inch rough nominal thickness; it does not guarantee a 1-inch surfaced board.
Does the result include waste?
The exact total does not. The recommended total applies the planning allowance you choose, starting at 0% so the tool does not invent a universal lumber waste rate.
Can I enter metric board dimensions?
Yes. Metric mode uses millimetres for thickness and width and metres for length. Switching units preserves the same physical dimensions.
How is lumber cost estimated?
Enter your supplier's price per board foot. The calculator multiplies that price by the recommended board feet; without a price, no cost is invented.
Sources and limitations
This tool estimates lumber volume and an optional purchase allowance. It does not select species or grade, predict surfaced thickness, build a cut list, evaluate moisture or defects, provide structural sizing, or retrieve live prices. Supplier billing rules and product details take priority.
- NIST units and systems of weights and measures
- NIST American Softwood Lumber Standard PS 20-10
- NHLA grading rules
Quarter sizes are rough nominal thickness shortcuts. Use the actual billed or measured thickness whenever the supplier basis or finished dimensions differ.
Last reviewed: August 28, 2026