How many studs do I need for a wall?

For standard 16-inch on-center spacing, divide the wall length in inches by 16, then add 1. A 12-foot wall needs (144/16) + 1 = 10 studs, plus extra studs for corners, doors, and windows. Add 2-3 studs per door and window opening.

What size lumber do I need for a 12-foot span?

For a 12-foot floor joist span with typical residential loads, you would need 2x10s at 16 inches on center or 2x12s at 24 inches on center. Always consult local building codes and span tables, as requirements vary by load conditions and wood species.

What is the difference between nominal and actual lumber sizes?

Nominal size is the name (2x4), while actual size is the true dimension after drying and planing. A 2x4 actually measures 1.5 x 3.5 inches. A 2x6 is 1.5 x 5.5 inches. This difference is important for accurate project planning.

How much lumber do I need for a 12x12 deck?

A 12x12 deck typically requires about 20 deck boards (5/4x6 at 12 feet), approximately 12 joists (2x8 or 2x10 at 12 feet), 2-3 beams, and 4-6 posts depending on your design. Add 10-15% extra for cuts and waste.

Should I use pressure-treated or regular lumber?

Use pressure-treated lumber for any wood that contacts the ground or is exposed to moisture, including deck framing, fence posts, and sill plates. Regular lumber is fine for interior framing and projects protected from moisture.

← All calculators

Lumber Calculator

Calculate board feet for decks, framing, and woodworking

0 calculations

Last verified: February 2026Accuracy tested

Calculated in your browser — we never store your dataIncludes standard waste factors

Thickness (in)

Width (in)

Length (ft)

Quantity

Price per Board Foot ($)

● National avg · updated Feb 20

Calculation Result

8.00 board feet

1 piece @ 2" × 6" × 8'

Estimated cost: $44

Price: $5.5/bf

Sources & Methodology

Formula: Board Feet = (T × W × L) / 12

Thickness(in) × Width(in) × Length(ft) / 12

Source: National Hardwood Lumber Association standard

View full methodology & accuracy testing

Think this result is wrong? Report an error

calc.alsoTry:Concrete Deck Fence Square Footage

Popular Calculations

2.67 board feet— How many board feet in a 1×4×8...3.33 board feet— How many board feet in a 1×4×1...4.00 board feet— How many board feet in a 1×4×1...5.33 board feet— How many board feet in a 1×4×1...6.67 board feet— How many board feet in a 1×4×2...4.00 board feet— How many board feet in a 1×6×8...5.00 board feet— How many board feet in a 1×6×1...6.00 board feet— How many board feet in a 1×6×1...

Estimate Your Project Cost

See total lumber project costs with labor →

Lumber & Framing Cost Guide on CostOnce.com

How to Use the Lumber Calculator

The lumber calculator helps you estimate board feet for woodworking projects or calculate studs and materials for wall framing. Whether you're building a deck, framing a room, or planning a furniture project, get accurate material estimates instantly.

Understanding Board Feet

Board feet is the standard unit for measuring hardwood lumber. The formula is: (Thickness × Width × Length) ÷ 12, where all measurements are in inches and length is converted to feet. One board foot equals a piece 1" thick × 12" wide × 1' long. For a deep dive into lumber math, check out our Complete Guide to Lumber Calculations.

Wall Framing Calculations

For standard wall framing, we calculate studs based on your spacing (typically 16" or 24" on center), plus three plates (bottom plate, top plate, and double top plate). Don't forget to account for headers, cripples, and extra studs at corners and openings. You'll also need drywall and insulation to complete your walls.

Tips for Accurate Estimates

Add 10-15% for waste, especially for rough-cut lumber
Check local codes for required stud spacing in load-bearing walls
Consider lumber grades when budgeting for your project

Related Calculators

Building a deck? You may also need our concrete calculator for footings, fence calculator for railings, and square footage calculator for decking coverage.

Frequently Asked Questions

Board feet = (thickness in inches x width in inches x length in feet) / 12. For example, a 2x6 board that is 8 feet long equals (2 x 6 x 8) / 12 = 8 board feet. This measurement is standard for pricing hardwood lumber.