Lumber Calculator
Calculate board feet from board dimensions, or find how many boards you need to cover a deck, floor, or fence.
Calculation type
Actual width e.g. 5.5 for 2×6
Actual e.g. 1.5 for 2× lumber
Actual width e.g. 5.5 for 2×6
0.25″ standard for decking
Results
Board Feet
—
board feet total
Per Board
—
board feet each
Linear Feet
—
total linear ft
How to Calculate Board Feet
A board foot equals 1 foot wide, 1 foot long, and 1 inch thick (144 cubic inches). It is the standard unit for pricing and ordering lumber.
Formula: Board Feet = (Thickness in × Width in × Length ft) ÷ 12.
Common Lumber Sizes — Nominal vs. Actual
| Nominal Size | Actual Size | Common Use |
|---|---|---|
| 2×4 | 1.5″ × 3.5″ | Framing, studs |
| 2×6 | 1.5″ × 5.5″ | Decking, joists |
| 2×8 | 1.5″ × 7.25″ | Joists, rafters |
| 1×6 | 0.75″ × 5.5″ | Fence boards, trim |
Frequently Asked Questions
- What is the difference between board feet and linear feet?
- Linear feet measures only length. Board feet measures volume — factoring in thickness and width. Lumber is priced in board feet; trim is priced in linear feet.
- Why do nominal and actual lumber sizes differ?
- Lumber is sized before drying and surfacing. A 2×4 starts at 2×4 but ends up at 1.5×3.5 after milling. Always use actual dimensions when calculating.
- How much extra lumber should I buy?
- 10% for straight layouts. Add 15–20% for diagonal or herringbone patterns that generate more angled cut waste.