Board Foot Calculator — Free Online Tool
Calculate board feet from thickness, width, length, and quantity. Get the formula, common lumber sizes, and a cost estimate in one free tool.
Dimensions
Quick Presets
Material & Quantity
Board Foot Calculator for Lumber Planning
Use the calculator above, then jump to the most common follow-up: formula, size lookup, lumber cost, or a batch tally.
Board foot formula
Thickness × width × length ÷ 12 when length is in feet. The calculator shows the same math with your numbers.
See formulaCommon board sizes
Quickly compare 4/4, 8/4, and 2x boards without building a separate spreadsheet.
View tablesCost per board foot
Pick a wood species or enter your own price per BF to estimate a lumber order before you buy.
Estimate costMultiple board sizes
Have a cut list with mixed widths and lengths? Add rows and total every board size in one batch.
Open batch toolWhat is a Board Foot?
A board foot (BF) measures lumber volume. One board foot equals 144 cubic inches of wood — picture a board 12 inches long, 12 inches wide, and 1 inch thick.
Lumber yards and sawmills use board feet to price rough-sawn hardwoods. The measurement accounts for all three dimensions, unlike linear feet (length only) or square feet (length × width).
This system started in North America and remains the standard for buying and selling hardwood lumber. Softwoods like construction lumber (2x4s) are often sold by linear foot, but the board foot still applies.
1 Board Foot = 144 cubic inches
144 cubic inches
Board Foot Formula
Two ways to calculate board feet
Length in Inches
Use when all dimensions are in inches
Length in Feet
Use when length is in feet
Multiple Boards
Multiply single board BF by count
How to Calculate Board Feet (Step by Step)
- 1
Step 1 — Measure thickness and width
Use inches for thickness and width. For quick estimates, nominal sizes (like 2×6) are fine. For tighter estimates, use actual sizes.
- 2
Step 2 — Enter the length
Enter length in feet or inches. If you use feet, the math divides by 12; if you use inches, it divides by 144.
- 3
Step 3 — Multiply by quantity
Set Quantity to match how many boards you’re buying. Total board feet scales linearly with count.
- 4
Step 4 — (Optional) estimate cost
Pick a wood species or enter $/BF to get a quick budget estimate.
Real-World Examples
Two common boards with their board feet (with the math).
| Input | Output | Notes |
|---|---|---|
| 2" × 6" × 8' (1 board) | 8 BF | (2 × 6 × 8) ÷ 12 = 8 |
| 1" × 8" × 10' (3 boards) | 20 BF | Per board: (1 × 8 × 10) ÷ 12 = 6.67 → Total: 6.67 × 3 ≈ 20 |
Common Mistakes to Avoid
These small details can change your totals.
Using nominal size when you need actual size
A “2×4” is often 1.5" × 3.5" after milling. If you need a tighter estimate, use actual dimensions.
Mixing inches and feet
Thickness and width should be in inches. If you switch length units, make sure the length input matches the selected unit.
Forgetting waste
For most projects, add 10–15% for offcuts, defects, and mistakes so you don’t run short.
Common Board Feet Reference
Quick lookup tables for standard lumber sizes, including 4/4, 8/4, and common 2x boards.
4/4 Lumber (1" Thick)
Standard hardwood thickness
| Width | 4' | 6' | 8' | 10' | 12' |
|---|---|---|---|---|---|
| 4" | 1.33 | 2.00 | 2.67 | 3.33 | 4.00 |
| 6" | 2.00 | 3.00 | 4.00 | 5.00 | 6.00 |
| 8" | 2.67 | 4.00 | 5.33 | 6.67 | 8.00 |
| 10" | 3.33 | 5.00 | 6.67 | 8.33 | 10.00 |
| 12" | 4.00 | 6.00 | 8.00 | 10.00 | 12.00 |
8/4 Lumber (2" Thick)
Double thickness hardwood
| Width | 4' | 6' | 8' | 10' | 12' |
|---|---|---|---|---|---|
| 4" | 2.67 | 4.00 | 5.33 | 6.67 | 8.00 |
| 6" | 4.00 | 6.00 | 8.00 | 10.00 | 12.00 |
| 8" | 5.33 | 8.00 | 10.67 | 13.33 | 16.00 |
| 10" | 6.67 | 10.00 | 13.33 | 16.67 | 20.00 |
| 12" | 8.00 | 12.00 | 16.00 | 20.00 | 24.00 |
2x Dimensional Lumber
Common construction lumber
| Width | 8' | 10' | 12' | 14' | 16' |
|---|---|---|---|---|---|
| 4" | 5.33 | 6.67 | 8.00 | 9.33 | 10.67 |
| 6" | 8.00 | 10.00 | 12.00 | 14.00 | 16.00 |
| 8" | 10.67 | 13.33 | 16.00 | 18.67 | 21.33 |
| 10" | 13.33 | 16.67 | 20.00 | 23.33 | 26.67 |
| 12" | 16.00 | 20.00 | 24.00 | 28.00 | 32.00 |
Frequently Asked Questions
Multiply thickness × width × length (all in inches), then divide by 144. For a 2×6×96 inch board: (2 × 6 × 96) ÷ 144 = 8 board feet. If length is in feet, divide by 12 instead of 144.