Board Foot Calculator

Board Foot Calculator

Calculate the board footage (board feet) of lumber needed for your woodworking projects. Board feet is a standard unit used in the lumber industry to estimate wood volume.

Last updated: March 2026

Standard: 0.75" (3/4"), 1", 1.5" (5/4")

2x4 = 3.5", 2x6 = 5.5", 2x8 = 7.25"

Per Piece
4
board feet
Total (1 pieces)
4
board feet

Disclaimer: This calculator computes board feet based on actual entered dimensions. Note that lumber sold commercially often has nominal dimensions (e.g., \"2×4\") that differ from actual milled dimensions (1.5\" × 3.5\"). Make sure you enter the correct actual dimensions for your lumber. Actual sizes, moisture content, shrinkage, waste, and defects may affect usable yield. Always purchase extra material.

What are Board Feet?

Board feet (BF) is a standard unit of measurement used in the lumber industry to quantify the volume of wood. One board foot represents a piece of wood measuring 1 inch thick, 12 inches wide, and 12 inches long—equivalent to 144 cubic inches. This standardization allows lumber dealers and woodworkers to compare prices and quantities across different board sizes.

Instead of purchasing thick boards and rough lumber by weight or physical count, the board foot measurement ensures you purchase exactly the volume of wood you need. This is especially useful for comparing the value of different lumber sizes; for example, a 2×4 is different from a 1×8, but their board footage can help determine which offers better value for your project.

How to Calculate Board Feet

The Board Foot Formula (Imperial)

Use this formula to calculate board feet for hardwoods and softwoods:

Board Feet = (Thickness in inches × Width in inches × Length in feet) ÷ 12
Note: Width and thickness are measured at the nominal size before milling (actual dimensions are slightly smaller)

Important Lumber Size Notes

Nominal vs. Actual:
A 2×4 is labeled as 2 inches by 4 inches but actually measures 1.5" × 3.5" after milling. Always use the nominal size for calculations.
Common Thicknesses:
Rough lumber: 4/4 (1"), 5/4 (1.25"), 6/4 (1.5"), 8/4 (2"). S4S (surfaced): typically 0.75" nominal.
Power of Twelve:
The division by 12 converts from cubic inches to board feet (1 BF = 144 cubic inches).

Example: Board Feet for a 2×6 Board

Calculating board feet for a nominal 2×6 board 12 feet long:

Step 1:
Identify the dimensions:
Thickness (T) = 2", Width (W) = 6", Length (L) = 12 ft
Step 2:
Apply the formula:
(2 × 6 × 12) ÷ 12
Step 3:
Calculate:
(2 × 6 × 12) ÷ 12 = 144 ÷ 12 = 12 BF
Result:
One 2×6 × 12 ft board = 12 board feet
✓ This is the standard volume measurement used by lumberyards

Frequently Asked Questions

Why use board feet instead of just counting pieces?

Board feet accounts for different lumber dimensions. A 2×4 and a 2×6 take up different volume, so board feet allows fair pricing and comparison across different sizes.

What's the difference between S4S and rough lumber?

S4S (Surfaced-4-Sides) lumber is milled smooth; rough lumber is not. Calculate using nominal dimensions in both cases, but S4S will actually be slightly smaller.

How do I calculate board feet for hardwood vs. softwood?

The formula is identical for hardwood and softwood. The only difference is the pricing per board foot, which varies by species.

Can I buy lumber by linear footage instead?

Yes, but linear footage only accounts for length. You'd need to specify the exact dimensions (2×4, 2×6, etc.). Board feet is more universal for pricing.

Why is my actual board smaller than the nominal size?

All lumber is milled (surfaced) to remove saw marks and unevenness. Nominal 2×4 becomes 1.5×3.5 after milling. Always use nominal for calculations.

How do I estimate long-term costs using board feet?

Multiply total board feet × price per board foot = total cost. Get the per-BF price from your lumberyard to make accurate project budgets.

Is there a metric equivalent to board feet?

Metric uses cubic meters or cubic centimeters directly. 1 board foot ≈ 0.00236 cubic meters or 2,360 cubic centimeters.

How do I account for shrinkage and waste?

Add 10-20% to your calculated board footage for sawkerf loss, planing waste, and mistakes. This ensures you order enough material.

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