Lumber Calculator
Free lumber calculator that converts board dimensions into board feet and total cost. Use it as a board foot calculator for framing, decking, and hardwood, and multiply by quantity for the whole order.
Calculate board feet
How the lumber calculator works
Lumber is priced and ordered in board feet, and this lumber calculator makes the conversion painless. A board foot is 144 cubic inches — picture a plank 1 inch thick, 12 inches wide, and a foot long. The board foot calculator formula is thickness × width in inches times length in feet, divided by 12. A single 2x4x8 comes to 5.33 board feet.
Need a whole order? Enter a quantity and the lumber board foot calculator multiplies through, so you can calculate lumber for an entire wall or a deck lumber calculator joist list in one step, then attach a price per board foot for the total.
Nominal vs actual size
Board feet use nominal dimensions — a 2x4 is called two-by-four even though it actually measures 1.5 × 3.5 inches after milling. Lumber yards price by the nominal board foot, so this board foot calculator lumber tool uses the nominal numbers you read off the tag. For weight or shipping, a separate lumber weight calculator would apply a density figure to the actual volume.
How to use this calculator
- Enter the board dimensions. This lumber calculator uses nominal thickness and width in inches and length in feet. For a 2x4x8 you enter 2, 4, and 8 — the standard way a board foot calculator measures framing stock.
- Compute board feet. As a lumber board foot calculator it multiplies thickness × width × length and divides by 12. A 2x4x8 works out to (2 × 4 × 8) ÷ 12 = 5.33 board feet per piece.
- Multiply by quantity. Enter how many identical boards and the calculate lumber step multiplies board feet by the count, so you can price a whole framing or deck lumber calculator order at once.
- Estimate the cost. Add a price per board foot and the tool returns the total cost. SPF framing in 2026 commonly runs $0.80–1.50 per board foot depending on grade and market.
Frequently asked questions
What is a board foot?
A board foot is 144 cubic inches of lumber — a piece 1 inch thick, 12 inches wide, and 1 foot long. This board foot calculator uses thickness × width × length ÷ 12.
Does the lumber board foot calculator use nominal or actual size?
Nominal. A 2x4 is priced as two-by-four even though it measures 1.5 × 3.5 inches, so enter the nominal numbers from the tag.
How do I calculate lumber for a whole order?
Enter the board dimensions and a quantity. The calculate lumber step multiplies board feet per piece by the number of identical boards.
Can I use it as a deck lumber calculator?
Yes. Work out board feet for each joist, beam, and decking size, then add the pieces — the deck lumber calculator logic is just board feet repeated per part.
What does lumber cost per board foot in 2026?
SPF framing commonly runs about $0.80–1.50 per board foot in 2026, varying by grade, length, and market; enter your local price for an accurate total.
Board feet for common lumber
| Board | Length | Board feet |
|---|---|---|
| 2×4 | 8 ft | 5.33 bd ft |
| 2×6 | 8 ft | 8.00 bd ft |
| 2×10 | 12 ft | 20.00 bd ft |
Multiply by your price per board foot to compare orders across dimensions.