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From Tree to Table · Part 5 of 9

How Board Feet Work

Hardwood is priced by volume in board feet — not by the finished size you will mill to. One board foot is 144 cubic inches of wood: a piece 1" thick × 12" wide × 12" long, measured at nominal rough thickness.

Board-foot math is how every commercial dealer tallies a ticket. It is also the place beginners get burned — they multiply finished dimensions, forget waste, or assume a surfaced 4/4 board is still priced as 3/4". Once board feet click, the rest of the store makes sense.

The formula

BF = Thickness (in) × Width (in) × Length (in) ÷ 144

Always use the nominal rough thickness in the formula — even if the board is already S2S. A 4/4 board planed to 13/16" still counts as 1" in the math. You are paying for the wood it took to make that blank, including the shavings on the mill floor.

Worked example

Suppose you need several parts from 4/4 cherry:

  • Board A: 1" (4/4 nominal) × 6" × 96" → (1 × 6 × 96) ÷ 144 = 4 BF
  • Board B: 1" × 8" × 84" → (1 × 8 × 84) ÷ 144 = 4.67 BF
  • Board C: 1" × 5" × 72" → (1 × 5 × 72) ÷ 144 = 2.5 BF

Subtotal: 11.17 BF before waste. Add 15–30% for planing loss, defects, grain rejects, and miscuts — more for figured stock or a first big glue-up. That buffer is not padding; it is how real shops buy.

Why nominal thickness matters at checkout

Surfacing removes material, but dealers price the original rough thickness so everyone tallies the same way. If two stores quoted you different thickness numbers for the same physical board, you could not compare prices.

When someone asks “why am I paying for an inch when it measures 13/16?", this is the answer. Point them to the quarter tag on the bundle, not the caliper on the surfaced face.

Board feet vs. linear feet

Board foot is volume — the standard at hardwood dealers. Linear foot is length of a piece with a fixed width and thickness — common for S4S moulding and pre-sized boards. Do not convert fixed-size linear-foot thinking into dealer board-foot pricing; the units are different products.

From cut list to boards

  1. Write finished part sizes (length × width × finished thickness).
  2. Convert each part to board feet at the rough thickness you will buy (4/4, 5/4, etc.).
  3. Sum the parts, then add waste.
  4. Look through the boards with the total in mind and pull extra width for grain match and defect cut-around.

Quick FAQ version: How is hardwood lumber sold? and How much wood for my project?

Class exercise: Bring a cut list on paper. We will tally board feet together on a real bundle before you commit — same math the register uses, no surprises at the counter.