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Board Feet Calculator

Calculate board feet per piece, total board feet, waste-adjusted board feet, and optional lumber cost from thickness, width, length, and quantity.

Enter lumber thickness in inches, such as 1, 1.25, 1.5, or 2.

Enter board width in inches.

Enter board length in feet.

Enter number of matching boards or pieces.

Optional extra percentage for cuts, defects, selection, and project waste.

Optional lumber price for a rough material cost estimate.

Status: initial

Results

Awaiting calculation

Guide

Introduction

The Board Feet Calculator estimates lumber volume from board thickness, width, length, and quantity. It is useful for woodworking, furniture building, sawmill estimates, and rough lumber purchasing.

Purpose

Use this calculator to estimate board feet per piece, total board feet, waste-adjusted board feet, and optional lumber cost before comparing lumber options or requesting a supplier quote.

How board feet are calculated

A board foot is a volume measure equal to a board 1 inch thick, 12 inches wide, and 1 foot long. The common lumber formula multiplies thickness in inches by width in inches by length in feet, then divides by 12.

Variable explanations

Thickness

The lumber thickness in inches.

Width

The board width in inches.

Length

The board length in feet.

Quantity

The number of matching boards or pieces.

Waste allowance

Optional extra board footage for cuts, defects, and selection.

Price per board foot

Optional supplier price used only for a rough cost estimate.

Formula and method guide

Board feet per piece

Board feet = thickness(in) x width(in) x length(ft) / 12

  • Thickness and width are in inches.
  • Length is in feet.

This gives the board footage for one board or lumber piece.

Total board feet

Total board feet = board feet per piece x quantity

  • Quantity is the number of matching pieces.

This scales one board's volume across multiple identical pieces.

Waste-adjusted board feet

Board feet with waste = total board feet x (1 + waste / 100)

  • Waste accounts for cuts, defects, and selection.

Use this as a planning number when estimating how much lumber to buy.

Worked examples

4/4 board

  1. Enter 1 inch thickness.
  2. Enter 8 inches width.
  3. Enter 8 feet length.

8/4 board

  1. Enter 2 inches thickness.
  2. Enter width and length.
  3. Review board feet per piece.

Multiple pieces

  1. Enter dimensions for one matching board.
  2. Enter quantity.
  3. Review total board feet.

Budget estimate

  1. Enter price per board foot.
  2. Add a waste allowance.
  3. Use estimated cost as planning context only.

Common mistakes

Mixing length units

This calculator expects length in feet, not inches.

Forgetting the divisor

When thickness and width are inches and length is feet, divide by 12.

Ignoring nominal dimensions

Nominal lumber dimensions may differ from actual measured size, depending on product and supplier.

Skipping waste

Cuts, knots, defects, grain selection, and mistakes can increase required board footage.

FAQs

What does this Board Feet Calculator calculate?
It calculates board feet per piece, total board feet, board feet with waste, and optional estimated lumber cost.
What is a board foot?
A board foot is a lumber volume equal to 1 inch thick, 12 inches wide, and 1 foot long.
What formula is used?
Board feet equals thickness in inches times width in inches times length in feet divided by 12.
Why divide by 12?
The divisor converts inch-based thickness and width with foot-based length into board-foot volume.
Can I use decimal thickness?
Yes. Decimal thickness values such as 1.25, 1.5, and 2 are supported.
What does 4/4 lumber mean?
In many rough lumber contexts, 4/4 refers to about 1 inch nominal thickness before surfacing.
What does 8/4 lumber mean?
8/4 commonly refers to about 2 inches nominal thickness before surfacing.
Should I use nominal or actual dimensions?
Use the dimensions your supplier uses for pricing or tallying. For project fit, also check actual measured dimensions.
Does this calculate linear feet?
No. Board feet measure volume, while linear feet measure length. They are not interchangeable without thickness and width.
Does this work for plywood?
It can estimate volume, but plywood is often sold by sheet, so a sheet or panel calculator may be more practical.
Does this work for logs?
No. Log scaling uses different rules such as Doyle, Scribner, or International rules.
Why include waste allowance?
Woodworking projects often need extra material for cuts, defects, grain matching, and board selection.
Is the cost estimate final?
No. It uses price per board foot only and does not include tax, milling, delivery, minimums, or supplier fees.
Can I calculate several board sizes at once?
This version calculates one matching group at a time. Add separate groups manually for mixed dimensions.
Is this a replacement for a lumber tally?
No. It is a planning calculator and should be checked against the supplier's final tally and measurement rules.

References

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Last updated and version history

Last updated: 2026-07-05

  • 1.0.0 (2026-07-05): Initial board feet calculator release.