How do I calculate board feet?

Multiply the thickness in inches by the width in inches by the length in feet, then divide by 12. Or use the formula: BF = (T × W × L) / 144 when length is in inches.

What is the difference between nominal and actual lumber size?

Nominal size is the name used when ordering lumber (e.g., 2x4). Actual size is the real dimension after milling and drying — a nominal 2x4 measures 1.5 inches × 3.5 inches. Board feet are calculated from nominal dimensions.

Board Foot Calculator

Calculate lumber quantities in board feet — with species pricing, grade comparison, and project presets

Lumber Pieces

Qty	Thickness in	Width in	Length ft	BF Each	Total BF

Waste Factor

10%

Price per BF ($)

Total Board Feet 0.0 BF

Net BF 0.0

Waste 0.0

Order 0.0 BF

Total Pieces 0

Net BF 0.0

With Waste 0.0 BF

Weight (est.) 0 lbs

Material Cost $0.00

Cost + Tax (8%) $0.00

Board Feet by Piece

Compare Species & Grades

Enter your total board feet to compare species and grade pricing side by side.

Board Feet to Price

Region

Price Comparison (per 100 BF)

Project Presets

Load a common project template to quickly estimate lumber quantities.

Select a preset to load

Click any project card on the left to populate the calculator with a typical lumber list.

Nominal vs. Actual Lumber Sizes

Lumber is sold by nominal size, but the actual milled dimensions are smaller. Board feet are calculated from nominal dimensions.

Nominal	Actual (in)	BF per 12 ft
1×2	0.75 × 1.5	2.0
1×3	0.75 × 2.5	3.0
1×4	0.75 × 3.5	4.0
1×6	0.75 × 5.5	6.0
1×8	0.75 × 7.25	8.0
1×10	0.75 × 9.25	10.0
1×12	0.75 × 11.25	12.0
2×2	1.5 × 1.5	4.0
2×3	1.5 × 2.5	6.0
2×4	1.5 × 3.5	8.0
2×6	1.5 × 5.5	12.0
2×8	1.5 × 7.25	16.0
2×10	1.5 × 9.25	20.0
2×12	1.5 × 11.25	24.0
4×4	3.5 × 3.5	16.0
4×6	3.5 × 5.5	24.0
6×6	5.5 × 5.5	36.0

Board Foot Formula

Board Feet BF = (T × W × L) ÷ 144 T & W in inches, L in inches

Alt: Length in Feet BF = (T × W × L) ÷ 12 T & W in inches, L in feet

With Waste Order = Net BF × (1 + Waste%) 10% waste is typical

Lumber Cross-Section

Select size:

Common Length Standards

Stock Length	Notes
8 ft (96 in)	Most common; good for 8 ft walls
10 ft (120 in)	Good for long horizontal runs
12 ft (144 in)	Standard deck boards
14 ft (168 in)	Rafters, headers
16 ft (192 in)	Long spans, decking
20 ft (240 in)	Structural beams

How to Calculate Board Feet

Measure your lumber — Record thickness (T) and width (W) in inches, and length (L) in feet.

Apply the formula — BF = (T × W × L) ÷ 12 when L is in feet, or divide by 144 when all measurements are in inches.

Add a waste factor — A 10% waste allowance is typical for straight cuts; add 15–20% for projects with lots of miters or angles.

Multiply by price per BF — Prices range from $0.80/BF for #2 SPF up to $8+/BF for hardwoods like walnut or cherry.

Lumber Glossary

Board Foot (BF) — Unit of lumber volume: 1" × 12" × 12" = 1 BF.

Nominal Size — The size used when ordering, e.g., 2×4. Larger than actual milled size.

Actual Size — The real dimension after milling. A 2×4 is actually 1.5" × 3.5".

Linear Foot (LF) — Length measurement only, no thickness/width. Used for trim and molding.

SPF — Spruce-Pine-Fir. Most common framing lumber species group. Moderate strength, widely available.

Douglas Fir — Stronger than SPF. Used for heavy framing, beams, and posts.

#2 Grade — Most common structural grade. Allows knots and minor defects. Used for framing.

Select Structural — Highest structural grade. Tight grain, minimal defects. Used for exposed beams.

Frequently Asked Questions

What is a board foot of lumber?

A board foot is a unit of lumber volume equal to a piece 1 inch thick, 12 inches wide, and 12 inches long — that's 144 cubic inches or 1/12 of a cubic foot. It's the standard unit for buying and selling lumber in the United States.

How many board feet are in a 2×4×8?

A 2×4×8 contains (2 × 4 × 96) ÷ 144 = 5.33 board feet using nominal dimensions. Using actual dimensions (1.5 × 3.5 × 96) ÷ 144 = 3.5 BF. Lumber is typically priced by nominal board feet, not actual.

How much waste factor should I add?

For straight cuts (framing, joists), add 10% waste. For diagonal cuts or patterns (decking, flooring), add 15%. For complex angles, miters, or lots of waste cuts, add 20%. Always round up to the nearest standard length when ordering.

What's the difference between board feet and linear feet?

Board feet measure volume (thickness × width × length) while linear feet measure length only. Board feet are used to price dimensional lumber; linear feet are used to price trim, molding, and material sold in rolls. A 100 linear feet of 1×4 contains 33.3 board feet.

Which species of lumber is best for framing?

SPF (Spruce-Pine-Fir) and Douglas Fir #2 are the most common framing species. SPF is more affordable and widely available. Doug Fir is stronger and stiffer — preferred for long spans, beams, and high-load applications. For pressure-treated applications (ground contact, decking), Southern Yellow Pine is the standard.