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Construction

Lumber Board Foot Calculator

Hardwood lumber is sold by the board foot — the universal unit that normalizes random widths and lengths into one price-able number. 1 board foot = 144 cubic inches = a 12" × 12" × 1" block of wood. A piece of 4/4 hardwood (1" thick nominal) that's 6" wide and 8 ft long = 4 board feet. Multiply by the yard's $/bf price and you've got the cost. This calculator handles thickness + width + length + piece count + optional $/bf for instant cost estimates. Critical for any woodworker, builder, or homeowner shopping at a hardwood dealer or rough-cut lumber yard.

Enter lumber dimensions.

The formula

Board feet = (thickness in × width in × length ft) ÷ 12

One board foot = 144 cubic inches — a 12×12×1-inch block. Multiply for total per piece, multiply by quantity for total order.

Nominal vs actual dimensions in hardwood

Hardwood lumber thickness is described in quarters of an inch (quarter notation):

  • 4/4 = 1 inch nominal (~13/16" after surface planing, ~7/8" rough)
  • 5/4 = 1.25 inch nominal (~1-1/8" after planing)
  • 6/4 = 1.5 inch nominal (~1-5/16" after planing)
  • 8/4 = 2 inch nominal (~1-13/16" after planing)
  • 12/4 = 3 inch nominal (~2-3/4" after planing)
  • 16/4 = 4 inch nominal

Board feet are always calculated on nominal dimensions — the rough size before milling — even though you'll receive less wood after planing/joining. The yard's price reflects the rough volume.

Worked example: 50 board feet of 8/4 cherry at $12/bf. Total cost: $600. After milling to 1-13/16" thick + S2S (surfaced two sides) you might lose 1/4-3/8" of thickness but you still paid for 8/4 volume.

Hardwood pricing 2025 ballpark

  • Poplar: $3-5/bf (cheap utility hardwood)
  • Soft maple: $4-6/bf
  • Red oak: $5-7/bf
  • White oak: $7-10/bf (popular for furniture, flooring)
  • Hard maple: $7-10/bf
  • Cherry: $8-12/bf
  • Walnut: $10-18/bf
  • Hickory: $7-10/bf
  • White ash: $6-9/bf
  • Mahogany / Sapele: $14-25/bf
  • Ipe / Teak: $20-35/bf
  • Specialty (curly, quilted, figured maple): $30-100+/bf

How to use this calculator

  1. Thickness in inches (use nominal, not actual after planing).
  2. Width in inches.
  3. Length in feet.
  4. # of pieces: how many boards of this dimension.
  5. Price per board foot (optional): yard's quoted price for instant cost.
  6. Output: total board feet, per-piece bf, estimated total cost.

Common scenarios

Dining table top: 6 pieces of 4/4 walnut, 8" wide × 8 ft. Per piece: 1 × 8 × 8 / 12 = 5.33 bf. Total: 32 bf. At $14/bf = $448 for the top alone. Buy 35 bf to allow for jointing waste.

Built-in bookcase: 12 pieces of 4/4 white oak, 12" wide × 6 ft (shelves), plus 4 pieces of 4/4 × 12" × 8 ft (sides). Shelves: 12 × 6 = 72 bf. Sides: 4 × 8 = 32 bf. Total 104 bf. At $8/bf = $832 in lumber.

Chair legs: 8 pieces of 8/4 hard maple, 3" wide × 30 inches (2.5 ft). Per piece: 2 × 3 × 2.5 / 12 = 1.25 bf. Total 10 bf. At $9/bf = $90.

FAQ

Nominal vs actual dimensions — why does it matter? +
For board foot pricing: use nominal. For project planning: use actual after planing. A 4/4 board priced as 1" thick yields ~13/16" after S2S planing — plan your design around the thinner actual dimension, not the nominal.
Why is hardwood sold in board feet instead of linear feet? +
Hardwood lumber comes in random widths (RW&L — random width and length). Two boards of the same 4/4 oak might be 6" and 11" wide. Board feet normalize volume so price reflects actual material, not just length.
What does "S2S" mean? +
Surfaced 2 Sides — the yard ran the boards through a planer to smooth two faces but left edges rough. S4S (surfaced 4 sides) is fully milled. Rough = no planing, you mill it yourself. S2S adds $0.50-1.50/bf to the price and saves you significant shop time.
How much waste should I plan? +
For straightforward rectangular pieces: 15-20% over actual project bf. For complex joinery: 25-30%. For specialty / figured wood where you're hunting specific grain patterns: 40-50%. Always order more than you think you need — matching wood for an add-on is hard.
What's the difference between FAS, Select, #1 Common, and #2 Common grades? +
Hardwood grades by clear-cutting yield. FAS (First and Seconds): 83% clear, longest clear cuttings — furniture grade. Select: similar yield, shorter clear cuttings allowed. #1 Common: 66% clear, smaller pieces — great value for built-ins. #2 Common: 50% clear, lots of character marks — paint-grade or rustic. Lower grades are cheaper and often perfect for projects where character is wanted.
Can I use this for softwood (2x4s, etc.)? +
Yes, but softwood is usually sold by piece (not bf) at construction lumberyards. The formula still works: a 2x4 × 8 ft has board feet = 2 × 4 × 8 / 12 = 5.33 bf nominal. But you'll pay per board, not by bf, at the big box.
Should I buy kiln-dried or air-dried lumber? +
Kiln-dried (KD) is dried to 6-8% moisture content — stable for indoor use. Air-dried lands at 12-15% — acclimate it in your shop for 6+ months before use. KD costs 10-20% more but eliminates the wait. For most projects, buy KD.
How much will hardwood lumber weight? +
Roughly: 25-50 lb per cubic foot air-dry. A board foot weighs ~3-4 lb air-dry depending on species. 100 bf of cherry weighs ~340 lb. Plan accordingly when transporting from yard to shop.