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Lumber Calculator

Calculate board feet and pieces of lumber needed for any project. Enter board dimensions and piece count — includes a 15% waste allowance and optional cost estimate.

Board Dimensions

e.g. 1 (1×6), 1.5 (2×4), 3.5 (4×4)

e.g. 6 (1×6), 3.5 (2×4), 5.5 (1×6 actual)

Standard: 8, 10, 12, 16 ft

Number of boards in the project

Typical: 10–15% for cuts and defects

Cost Estimate (optional)

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02 Result
Board Feet (with waste)
46 bd ft
12 pieces · 96 linear ft
Per piece4 bd ft
Base total (10 pcs)40 bd ft
Waste (15%)46 bd ft
Pieces to buy12 pieces
Linear feet to buy96 linear ft

About This Calculator

Enter the nominal board dimensions (thickness, width, length), piece count, and waste allowance — and instantly see the total board feet, pieces to buy, and linear footage. Add per-board-foot or per-linear-foot pricing for a total material cost estimate.

How It Works

Board feet per piece = (thickness × width × length) ÷ 12. Total board feet = board feet per piece × piece count. With waste = total × (1 + waste %). Pieces to buy = ⌈total with waste ÷ board feet per piece⌉ (always round up). Linear feet = pieces × board length.

The Formula

bd ft = (T × W × L) ÷ 12

T
nominal thickness in inches
W
nominal width in inches
L
board length in feet
12
board foot divisor (NHLA standard)

Frequently Asked Questions

What is a board foot?
A board foot (bd ft) is the standard US lumber volume unit equal to a board 12 inches × 12 inches × 1 inch thick (144 cubic inches). It's calculated as (thickness in inches × width in inches × length in feet) ÷ 12. Hardwood is sold by the board foot; softwood framing lumber is often sold by linear foot.
Should I use nominal or actual dimensions?
This calculator uses the dimensions you enter — enter whichever your supplier quotes. Note that a "2×4" is actually 1.5×3.5 inches (actual), not 2×4 (nominal). For ordering purposes, lumber suppliers quote board feet using nominal dimensions; for volume calculations, actual dimensions give the true wood volume.
Why add a waste allowance?
Every project involves off-cuts at the ends of boards, pieces rejected for knots or defects, and measurement errors. A 10% waste allowance is standard for clean rectangular cuts; 15% is typical for projects with angled cuts or variable-quality lumber. Complex shapes (arches, curves, multiple angles) may need 20–25%.
What is the difference between board feet and linear feet?
A linear foot is simply the length of a board (1 foot of any width/thickness). Board feet account for volume — a wider or thicker board has more board feet per linear foot. Linear feet are useful for estimating coverage; board feet are used for pricing hardwood and calculating total wood volume.

Estimates only. Coverage figures (sq ft/gallon, bag yield, BTU/sq ft) are industry rules of thumb with real-world variance. Verify quantities with your supplier before purchasing.