Board Foot Pricing Calculator: How to Use It

This calculator works out the total board feet of lumber you need and its price based on the dimensions you enter. You input the thickness, width, and length of each board (in inches and feet), the number of boards, and the price per board foot; it returns the total board feet and the total cost. It uses the standard lumber industry formula: board feet = (thickness in inches × width in inches × length in feet) ÷ 12.

Formula

The formula for one board is:

Board Feet = (Thickness (in) × Width (in) × Length (ft)) ÷ 12

Where:

• Thickness is in inches (e.g., 1 in, 2 in, 4 in)
• Width is in inches (e.g., 4 in, 6 in, 12 in)
• Length is in feet (e.g., 8 ft, 10 ft, 12 ft)
• 12 is the conversion factor (1 foot = 12 inches)

The result is in board feet (bd ft), a unit of volume equal to 144 cubic inches. For multiple boards, multiply the single-board result by the number of boards. To get the cost, multiply total board feet by the price per board foot.

Worked Example

Using the default values: thickness = 1 in, width = 6 in, length = 8 ft, number of boards = 1, price per board foot = $3.50.

1. Multiply thickness × width × length: 1 × 6 × 8 = 48
2. Divide by 12: 48 ÷ 12 = 4 board feet
3. Multiply by number of boards: 4 × 1 = 4 board feet
4. Multiply by price: 4 × $3.50 = $14.00

The calculator shows 4.00 board feet and a total cost of $14.00.

Why Use Board Feet Instead of Cubic Feet or Linear Feet?

Board feet is the standard unit for buying rough-sawn lumber in North America. It measures volume, not just length, so it accounts for thickness and width. A 1×6×8 board is 4 board feet, while a 1×12×8 board is 8 board feet—even though both are 8 feet long. This allows sawmills and lumberyards to price lumber consistently regardless of how it is cut. Linear feet only measure length, which is fine for trim or molding but not for structural lumber. Cubic feet is a larger unit (1 cubic foot = 12 board feet) and is rarely used for lumber pricing.

How to Measure Lumber for the Calculator

To get accurate results, measure the actual dimensions of your lumber, not the nominal (named) size. For example, a “2×4� actually measures 1.5 inches by 3.5 inches. If you use nominal dimensions, you will overestimate board feet. Here are the steps:

• Measure thickness in inches with a tape measure or caliper.
• Measure width in inches at the widest point (for rough lumber, use the average width).
• Measure length in feet (if you have inches, convert to feet by dividing by 12).
• Count the number of identical boards.
• Enter the price per board foot (your supplier will quote this).

For tapered boards, use the average width. For multiple different sizes, calculate each group separately and add the totals.

Common Mistakes and How to Avoid Them

The most frequent error is mixing units. The formula requires thickness and width in inches, and length in feet. If you measure length in inches, you must divide by 12 first. Another common mistake is using nominal dimensions instead of actual ones—a 2×4 is not 2×4 inches. Also, remember that board feet is a volume, so a 1×12×12 board (12 board feet) has the same volume as a 2×6×12 board (also 12 board feet), even though they look different. Finally, don’t forget to multiply by the number of boards if you have more than one.

Limits of the Formula

This formula gives the nominal board feet, which is what lumberyards use for pricing. It does not account for waste or defects. When you buy rough lumber, you may lose some material to warping, knots, or milling. Many woodworkers add 10–20% extra to their order to cover waste. The formula also assumes a rectangular cross-section; if your board is irregular, the result is an approximation. For engineered wood products like plywood, board feet is not used—plywood is sold by the sheet (e.g., 4×8 feet).

Comparing Prices: What Does “Price per Board Foot� Mean?

Lumberyards often quote prices per board foot, but the actual price depends on grade, species, and market conditions. For example, a 1×6×8 board at $3.50 per board foot costs $14.00, but the same board in a higher grade might be $5.00 per board foot, costing $20.00. When comparing prices, always ask for the price per board foot and the grade. Some suppliers sell by the linear foot for certain products, so be sure you are comparing the same unit. This calculator helps you convert between the two: multiply price per linear foot by 12 divided by (thickness × width) to get price per board foot.

Frequently Asked Questions

How do I convert board feet to cubic feet?

Divide the number of board feet by 12. Since 1 cubic foot = 12 board feet, 100 board feet equals approximately 8.33 cubic feet.

What is the difference between nominal and actual lumber dimensions?

Nominal dimensions are the rough-sawn size before drying and planing. Actual dimensions are the final finished size. For example, a nominal 2×4 is actually 1.5×3.5 inches. Always use actual dimensions for accurate board foot calculations.

Can I use this calculator for metric measurements?

No, the formula is designed for inches and feet. To use metric, convert centimeters to inches (divide by 2.54) and meters to feet (multiply by 3.28084), then enter those values.

Why is my lumberyard charging more than the calculated price?

The price per board foot may vary by grade, species, and quantity. Some yards also add a surcharge for cutting, delivery, or small orders. The calculator gives the base cost for the lumber itself.

How much extra should I order for waste?

For most woodworking projects, adding 10–20% to your board foot total is wise. If you are working with expensive or figured wood, you may want to add more to allow for defects and mistakes.

Does this formula work for hardwood and softwood?

Yes, the board foot formula is the same for all lumber types. Hardwoods are often sold by the board foot, while softwoods are sometimes sold by the linear foot, but the volume calculation is identical.

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in t | Thickness | in | 1 | 0
in w | Width | in | 6 | 0
in l | Length | ft | 8 | 0
in n | Number of boards | - | 1 | 0
in p | Price per board foot | $ | 3.50 | 0
out bf | Total board feet | bd ft | (t * w * l / 12) * n | 2
out cost | Total cost | $ | bf * p | 2