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Board Foot Calculator (Lumber & Hardwood)

Calculate board feet (FBM) for hardwood and dimensional lumber with cost estimates.

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How to Use the Board Foot Calculator

  1. 1Enter the lumber thickness in inches (e.g. 4/4 = 1 inch, 8/4 = 2 inches).
  2. 2Enter the width in inches.
  3. 3Enter the length in feet or inches.
  4. 4Optionally enter piece quantity and price per board foot to view total lumber cost.

Formula & How It Works

Board Foot Formula

Board Feet = (Thickness (in) × Width (in) × Length (ft)) / 12

One board foot equals the volume of a 1-inch thick piece of wood that is 12 inches wide and 12 inches (1 foot) long (144 cubic inches).

Worked Examples

Hardwood Walnut Board

Input: Thickness: 2 in, Width: 8 in, Length: 8 ft, Qty: 3

Explanation: (2 × 8 × 8) / 12 = 10.67 BF per board. 10.67 × 3 = 32 BF.

Result: 32.0 Board Feet Total (10.67 BF each)

Quarter Sawn White Oak (4/4 stock)

Input: 1 in × 6 in × 10 ft, Qty: 4 at $8.50/BF

Explanation: (1 × 6 × 10) / 12 = 5 BF per board. 5 × 4 = 20 BF. 20 × $8.50 = $170.

Result: 20.0 BF Total | Total Cost: $170.00

Frequently Asked Questions

What does 4/4, 6/4, or 8/4 mean in hardwood?▼

Hardwood thickness is measured in quarters of an inch: 4/4 is 1 inch thick, 6/4 is 1.5 inches thick, and 8/4 is 2 inches thick.

Is board foot measured before or after planing?▼

Board feet for rough hardwood are measured based on nominal rough-sawn dimensions before final surfacing (S2S/S4S).

Can length be entered in inches?▼

Yes, if length is entered in inches, the formula divides by 144: (T × W × L) / 144.

How do I account for woodworking scrap?▼

Woodworkers generally add 15% to 20% extra board footage to account for defects, milling, and kerf loss.

Last reviewed & updated: 2026-03-29
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