Skip to main content

learn.howToCalculate

learn.whatIsHeading

The Lumber Dimension Converter handles the confusing reality that lumber labeled "2×4" is not actually 2 inches × 4 inches — it's 1.5 × 3.5 inches actual. This nominal vs actual difference (a residual of historical milling standards before kiln drying) catches every beginner woodworker. The calculator converts nominal sizes (1×2 through 6×6) to actual inches and millimeters, calculates board feet (BF, the standard lumber volume unit), converts length units, and computes total project costs.

공식

Board Feet (BF) = (Nominal Thickness × Nominal Width × Length in feet) ÷ 12; Actual dimensions per US softwood standard table
BF
Board Feet (BF) — 1 BF = 144 cubic inches = ~0.00236 m³

단계별 가이드

  1. 1Select nominal lumber size from common dropdown (1×2 through 6×6)
  2. 2Enter length and unit (feet, inches, meters, centimeters)
  3. 3Enter quantity of pieces
  4. 4Enter price per board foot for cost calculation
  5. 5Calculator outputs total board feet, actual dimensions in inches and mm, length in all units, and total cost
  6. 6Board feet calculation uses nominal dimensions (industry standard)

풀어진 예시

입력
Five 2×4s at 8 feet, $3.50/BF
결과
BF = (2×4×8)/12 = 5.33 BF/piece × 5 = 26.67 BF, $93.33 total
입력
One 1×6 at 10 feet
결과
5 BF, actual 0.75″ × 5.5″, 254 mm length
입력
4×4 post at 8 feet
결과
10.67 BF, actual 3.5″ × 3.5″ — standard fence post

피해야 할 일반적인 실수

  • Calculating board feet using actual dimensions — must use nominal
  • Assuming 2×4 = 2 inches × 4 inches — it's 1.5 × 3.5 inches actual
  • Forgetting drying causes additional shrinkage — kiln-dried is more accurate than green
  • Mixing hardwood (often sold by actual) and softwood (sold by nominal) measurement systems

자주 묻는 질문

Why is 2×4 actually 1.5×3.5?

Original 2×4 was rough-sawn from green wood at 2×4 inches. Drying shrinks wood, and surfacing (planing for smooth surfaces) removes another ~¼ inch per side. By the time lumber reaches retail, dimensions are reduced — the industry kept the original "nominal" name for tradition and supply chain consistency.

Is there a metric equivalent?

Yes — most US 2×4s are sold as 38mm × 89mm internationally (actual measurements). Some European countries use slightly different sizing (45 × 95mm). When importing/exporting, the metric measurement is the actual size, not nominal.

계산할 준비가 되셨나요? 무료 Lumber Dimension Converter 계산기를 사용해 보세요

직접 시도해 보세요 →

설정

개인정보이용약관정보© 2026 PrimeCalcPro