How to calculate lumber quantity and cost
Use the calculator to turn board thickness, width, length, quantity, and a cost figure into total board feet and total cost. The Result section also shows the formula and intermediate values used.
Use the lumber calculator
- Select Cost per board or Cost per board foot.
- Enter Board thickness, Board width, Board length, and Number of boards. Choose the unit for each dimension from its selector.
- Enter the applicable cost for the selected cost mode.
- Click Calculate.
- Use Reset to restore the form's starting values.
Understand the Result section
The Result section displays total board feet, total cost, board feet per board, total linear length, the formula, and intermediate values such as converted dimensions and both cost figures. Calculations use the numeric values you enter. Displayed quantities are formatted to fixed decimal places, and money is displayed with two decimal places.
Use Copy result for a plain-text summary, or Download result (.txt) to save that summary as a text file.
Nominal and actual lumber dimensions
Enter the dimensions used by your supplier's pricing. The calculator does not convert a nominal size such as 2x4 into actual dressed dimensions, so nominal and actual entries can produce different results.
Costs, units, and validation
- Thickness and width: choose inches, millimeters, or centimeters for each dimension.
- Length: choose feet, inches, meters, or centimeters.
- Cost per board: the total cost is the entered cost multiplied by quantity.
- Cost per board foot: select this mode before entering a value such as $1.50; the total cost is then based on total board feet.
Board thickness must be 0.01 to 100, Board width 0.01 to 500, Board length 0.01 to 10,000, Number of boards 1 to 100,000 whole boards, and cost 0.01 to 1,000,000 in the selected cost mode. Invalid values stop the calculation and show an error. Input values are not silently defaulted or discarded; displayed results are formatted to fixed decimal places.
What the calculator does not include
The calculator does not look up supplier pricing or availability. It does not add waste, defects, taxes, delivery, fees, grade, species, or moisture allowances, and it does not provide structural advice. Treat the result as a mathematical estimate based on the figures you enter.
Privacy and calculation behavior
The calculator's calculation script uses your calculator values locally and does not send those values to a server during calculation. This statement applies to the calculator inputs, not to other page features such as analytics or the subscription form.
Frequently Asked Questions
What is the board feet formula?
Board feet per board = (Thickness in inches x Width in inches x Length in feet) / 12. Total board feet = Board feet per board x Quantity. For example, a 1.5 in x 3.5 in x 8 ft board (a nominal 2x4) is (1.5 x 3.5 x 8) / 12 = 3.5 board feet; 10 of those boards is 35 board feet.
Should I use cost per board or cost per board foot?
Use Cost per board if your supplier prices lumber by the individual board or linear piece. Use Cost per board foot if your supplier prices lumber by board footage, which is common for hardwoods and specialty lumber.
Should I enter nominal or actual (dressed) dimensions?
Enter whichever dimensions your supplier prices against - the calculator does not convert nominal sizes (like 2x4) to actual dressed sizes (like 1.5 in x 3.5 in) for you. Many suppliers price rough or nominal lumber by nominal size and surfaced/dressed lumber by actual size, so check your supplier's convention and enter that figure directly.
What units are supported?
Board thickness and width accept inches, millimeters, or centimeters. Board length accepts feet, inches, meters, or centimeters. Each dimension's unit is set independently.
Does this tool fetch live lumber pricing or give certified advice?
No. It performs a single, transparent calculation using only the dimensions, count, and cost figure you type in. It does not fetch supplier prices or lumber market data, and it is not certified lumber-purchasing or structural advice.