Lumber Calculator
Estimate boards needed and total board feet for framing, decking, fencing, walls and general construction projects.
This lumber calculator converts your project's length and width, along with your chosen board length, width and thickness, into the number of boards you need and the total board feet to order. It works for framing, decking, fencing, wall studs and general construction takeoffs. Enter your dimensions, add a waste percentage for cuts and irregular layouts, and optionally add a price per board to estimate total material cost.
Your Estimate
Project Area
240.0 ft²
Boards Required
66 boards
Total Board Feet
363.0 bd ft
Boards Including Waste
73 boards
Total Board Feet w/ Waste
401.5 bd ft
Board feet = (thickness in inches × width in inches × length in feet) ÷ 12. Coverage assumes boards are laid edge to edge across the project width with no gaps.
Results Actions
Estimates are approximate. Actual board counts can vary with layout, framing spacing, and cut waste at edges and corners.
Common Lumber Sizes Reference
Sizes shown are actual dressed dimensions. Enter these values into the board width and thickness fields above for accurate board feet calculations.
How to Use the Lumber Calculator
- 1Measure the length and width of your project area in feet.
- 2Enter the length, width and thickness of the boards you plan to use (see reference table below).
- 3Choose a waste percentage — 10% for simple layouts, 15%+ for angled cuts or complex framing.
- 4Optionally enter a price per board to see an estimated material cost.
- 5Read your results instantly: boards required, total board feet, and totals including waste.
Example Calculation
Say you're framing a 20 ft x 12 ft wall section using 8 ft long 2×6 boards (1.5 in thick, 5.5 in wide) with a 10% waste factor. Project area = 20 × 12 = 240 sq ft. Coverage per board = 8 × (5.5 ÷ 12) = 3.67 sq ft. Boards needed = 240 ÷ 3.67 = 66 boards. Board feet per board = (1.5 × 5.5 × 8) ÷ 12 = 5.5 bd ft, so total board feet = 66 × 5.5 = 363 bd ft. With 10% waste, boards including waste = 73 boards, or about 401.5 bd ft.
Accuracy & Assumptions
- Results are estimates only.
- Board counts and board feet can vary with layout pattern, framing spacing and cut waste.
- Consider ordering an additional 5–10% beyond the calculated waste for damaged or warped boards.
- Verify all project measurements before purchasing materials.
- Consult a licensed contractor or engineer for structural framing requirements.
Frequently Asked Questions
How many boards do I need for a framing or decking project?
Divide your total project area by the coverage of a single board (board length × board width). For a 240 sq ft area covered with 8 ft boards that are 5.5 inches wide, each board covers about 3.67 sq ft, so you would need roughly 66 boards before waste.
What is a board foot?
A board foot is a unit of lumber volume equal to a board 12 inches long, 12 inches wide and 1 inch thick. It is calculated as (thickness in inches × width in inches × length in feet) ÷ 12, and is commonly used when pricing rough or specialty lumber.
How much waste should I add to a lumber order?
Use 10% waste for straightforward framing or decking layouts, and 15% or more for projects with lots of cuts, angles, or a diagonal decking pattern.
Can this calculator be used for framing walls?
Yes. Enter the wall length as your project length and stud height as your project width to estimate the number of studs and total board feet needed, then adjust waste for corners, headers and blocking.
Does this calculator account for nominal vs. actual lumber dimensions?
No — enter the actual dressed dimensions of your lumber (for example, a nominal 2×6 is actually 1.5 in × 5.5 in) for the most accurate board count and board feet total.
This calculator provides an estimate for planning purposes only. Actual board counts, lumber grades and pricing vary by supplier — always confirm final quantities with your lumber yard before purchasing, and consult a licensed contractor for structural framing.