Lumber Calculator: Board Feet and Linear Feet for Any Project

Lumber pricing and measurement are a source of confusion for almost everyone who hasn't spent time in a lumber yard. Nominal sizes don't match actual sizes, board feet are different from linear feet, and pricing varies by species, grade, and whether the wood is treated. Understanding these basics means you can estimate projects and talk to suppliers without getting lost.

The CalcHub Lumber Calculator converts between nominal and actual sizes, calculates board feet, and estimates quantity for any framing or finish project.

Nominal vs. Actual Dimensions

The size stamped on lumber (the "nominal" size) isn't what you measure. This confuses DIYers constantly:

Nominal Size	Actual Size
1×2	¾" × 1½"
1×4	¾" × 3½"
1×6	¾" × 5½"
1×8	¾" × 7¼"
2×4	1½" × 3½"
2×6	1½" × 5½"
2×8	1½" × 7¼"
2×10	1½" × 9¼"
2×12	1½" × 11¼"
4×4	3½" × 3½"
6×6	5½" × 5½"

This matters a lot for structural calculations, finish carpentry, and when planning joints.

Board Feet: What It Is and When It Matters

Board feet is the standard volume measurement for rough-sawn or hardwood lumber: Board Feet = Thickness (in) × Width (in) × Length (ft) ÷ 12

For a 1×6, 8-foot board:
1 × 6 × 8 ÷ 12 = 4 board feet

For a 2×10, 12-foot board:
2 × 10 × 12 ÷ 12 = 20 board feet

Linear feet is used for softwood dimensional lumber (framing lumber, decking) — you just buy the number of pieces at the specific length.

Framing Lumber: Stud Calculation

For wall framing, the rule of thumb is 1 stud per linear foot of wall (at 16" o.c. stud spacing), including allowances for corners, openings, and headers. This covers studs, plates, and extra material.

For a 200 LF of wall framing (perimeter):

• Studs (16" o.c.): 200 pieces of 8-ft 2×4 studs


• Double top plates: 400 LF of 2×4


• Bottom plates: 200 LF of 2×4


• Add 10–15% for headers, corners, waste

Common Project Estimates

Project	Common Size	Typical Spacing	Notes
Interior wall stud	2×4	16" o.c.	8-ft or 9-ft length
Exterior wall stud	2×6	16" o.c.	Better insulation cavity
Floor joist	2×8 to 2×12	12–16" o.c.	Span determines size
Rafter	2×6 to 2×10	16–24" o.c.	Per span tables
Deck joist	2×8 (treated)	12–16" o.c.	Ground contact rated
Deck decking	5/4×6 (treated)	—	Actual: 1" × 5½"
Stair stringers	2×12	—	3 per stair width

Board Foot Pricing Example

Hardwood lumber (oak, maple, cherry) is sold by the board foot at specialty lumber dealers. Rough-sawn 4/4 (1" thick) white oak might run $5–$10 per board foot. For a tabletop project needing 30 board feet: $150–$300 in material.

This is why hardwood furniture is expensive — a solid walnut dining table might use 80–100 board feet of lumber at $12–$18/BF before any shop time.

What's the difference between S4S and rough-sawn lumber?

S4S (surfaced 4 sides) lumber is planed smooth on all four sides and ready to use — this is what you buy at a home center. Rough-sawn lumber from a sawmill is the same nominal size but oversized, and needs to be planed to final thickness. Rough-sawn is cheaper per board foot but requires a planer.

How do I account for wood movement?

Solid wood expands and contracts across the grain with humidity changes. For wide panels (tabletops, wainscoting), allow for seasonal movement in your joinery and fastening. Quartersawn lumber moves less than flat-sawn for the same reason.

What does "16d common nail" mean and how many do I need?

"d" means pennyweight, a historical size designation. 16d = 3.5" common nail, standard for framing. For stud framing, roughly 1 lb of 16d nails per 100 sqft of wall area is a reasonable estimate.

Related Tools

• Deck Calculator — complete deck material list
• Stair Calculator — stringer board length and stud count
• Drywall Calculator — what goes on the framing