About the Board Foot Calculator
This board foot calculator allows you to quickly estimate the volume of hardwood lumber you want to buy. Calculate board feet for single or multiple pieces of wood, and get instant cost estimates.
What is a Board Foot?
Unlike square footage, which measures area, board footage measures volume. You use it when purchasing multiple boards of lumber in various sizes.
By definition, one board foot of lumber is one square foot that is one-inch thick.
Board Foot Conversions
1 board foot = 144 cubic inches = 1/12 cubic foot
How to Calculate Board Feet?
Surprisingly, the calculations are extremely easy! All you need to do is use the board foot formula:
Board Feet = Length (ft) × Width (in) × Thickness (in) / 12
Pay special attention to the units!
- The length of the wooden board should be expressed in feet
- The width and thickness should be in inches
Using the Lumber Calculator: An Example
Let's assume you want to use this board foot calculator to determine how much you should pay for a few hardwood pieces.
Example Calculation
- Decide on the number of pieces: Let's assume it's 5 wooden boards.
- Choose the dimensions: Each piece is 8 feet long, 10 inches wide, and 1.25 inches thick.
- Calculate board footage per piece:
- board feet = 8 × 10 × 1.25 / 12
- board feet = 8.33 BF
- Multiply by number of pieces:
- 5 × 8.33 = 41.67 BF
- Calculate total cost:
- Assuming one board foot costs $4.15
- cost = 41.67 × $4.15 = $172.92
Common Lumber Dimensions
| Nominal Size | Actual Size | Common Lengths |
|---|---|---|
| 1x4 | 0.75" × 3.5" | 6', 8', 10', 12' |
| 1x6 | 0.75" × 5.5" | 6', 8', 10', 12', 14', 16' |
| 1x8 | 0.75" × 7.25" | 8', 10', 12', 14', 16' |
| 2x4 | 1.5" × 3.5" | 8', 10', 12', 14', 16' |
| 2x6 | 1.5" × 5.5" | 8', 10', 12', 14', 16', 18' |
| 2x8 | 1.5" × 7.25" | 8', 10', 12', 14', 16', 18' |
| 2x10 | 1.5" × 9.25" | 8', 10', 12', 14', 16', 18', 20' |
| 2x12 | 1.5" × 11.25" | 8', 10', 12', 14', 16', 18', 20' |
Board Feet in a 2x4
Here's how many board feet are in standard 2x4 lumber at different lengths:
| Length of 2x4 | Board Feet |
|---|---|
| 6 ft | 4 BF |
| 8 ft | 5.33 BF |
| 10 ft | 6.67 BF |
| 12 ft | 8 BF |
| 14 ft | 9.33 BF |
| 16 ft | 10.67 BF |
| 18 ft | 12 BF |
| 20 ft | 13.33 BF |
How to Measure a Board Foot?
- Take a rectangular piece of lumber
- Measure the length of it in feet, rounding to the nearest decimal place
- Measure the width in inches (or in feet, but then don't divide by 12 in step 5)
- Measure the thickness in inches
- Multiply all three numbers together and divide by 12
Board Foot vs Linear Foot
Board Foot
Type: Volume measurement
Formula: Width (ft) × Length (ft) × Thickness (in)
Used for: Pricing lumber, calculating material needs
Linear Foot
Type: Length measurement
Formula: Simple length measurement
Used for: Trim, molding, rope, piping
Board Foot in Logs
To calculate the board feet in a log:
- Find either a Doyle rule or the International 1/4-inch rule table
- Measure the diameter of the shorter end of the log (not including bark) in inches
- Measure the length of the log in feet
- Look up where the two values meet on the table
- Alternatively, use the equation:
((Diameter - 4)/4)² × Length
Hardwood Weights
Different wood species have different weights per board foot:
| Wood Type | Weight per Board Foot | Density |
|---|---|---|
| Oak | 3.08-4.67 lb (avg 3.875 lb) | 37-56 lb/ft³ |
| Pine (White) | 2.5-3.0 lb | 25-30 lb/ft³ |
| Maple | 3.5-4.5 lb | 35-45 lb/ft³ |
| Walnut | 3.5-4.0 lb | 35-40 lb/ft³ |
| Cherry | 3.0-3.5 lb | 30-35 lb/ft³ |
Practical Applications
- Construction Projects: Calculate total lumber needed for framing, decking, or fencing
- Woodworking: Estimate material costs for furniture and cabinet projects
- Purchasing Lumber: Compare prices from different suppliers on an equal basis
- Project Planning: Budget accurately for material costs in advance
- Insulation: Board foot is also used to measure spray foam insulation coverage
Tips for Buying Lumber
- Always buy 10-15% more than calculated to account for waste and cutting errors
- Check the actual dimensions vs nominal dimensions (a 2x4 is actually 1.5" × 3.5")
- Consider the moisture content - kiln-dried lumber costs more but is more stable
- Inspect boards for knots, warping, and defects before purchasing
- Ask about volume discounts when buying large quantities
- Different wood species have different costs per board foot
Note: Lumber prices can vary significantly based on species, grade, moisture content, and local market conditions. Always verify current pricing with your supplier before making large purchases.