Lumber Calculator

The Lumber Calculator estimates board feet based on lumber dimensions and quantity. This calculator helps woodworkers, contractors, and DIY enthusiasts determine lumber volume for projects. Whether you're planning a deck build, estimating material costs, or ordering hardwood, this tool provides quick board foot calculations.

Enter the length of each piece in feet (e.g., 8 for an 8-foot board)
Enter the width in inches (e.g., 5.5 for a 6-inch nominal board)
Enter the thickness in inches (e.g., 1.5 for a 2-inch nominal board)
Enter the number of identical pieces (e.g., 20 boards)

This calculator is for informational purposes only. Verify results with appropriate professionals for important decisions.

Use this free online Lumber Calculator to calculate your board feet. Simply enter your length, width, thickness, and quantity to instantly get results in board feet. Board feet represent the total volume of lumber for your project or purchase.

How Board Feet Is Calculated

Board feet is a standard unit for measuring lumber volume in North America. One board foot equals a piece of wood that is 1 inch thick, 12 inches wide, and 1 foot long. The calculator multiplies all three dimensions together along with the quantity, then divides by 12 to get the total board feet. This method gives you a consistent way to compare and order lumber regardless of the actual board sizes.

Board Feet = (Thickness × Width × Length × Quantity) ÷ 12

Where:

  • Thickness = lumber thickness in inches
  • Width = lumber width in inches
  • Length = lumber length in feet
  • Quantity = number of identical pieces

This formula works best when you use actual dimensions rather than nominal sizes. For example, a standard "2x4" actually measures 1.5 inches thick and 3.5 inches wide.

What Your Lumber Calculator Result Means

Your board feet result tells you the total volume of lumber in a standard unit that sawmills and lumber yards use for pricing. A higher board feet value means more wood and typically higher cost. For a single 8-foot 2x4, you get about 3.5 board feet. A small woodworking project might use 20 to 50 board feet, while building a deck could require 200 to 500 board feet. Hardwood is often priced per board foot, so knowing your total helps you estimate material costs.

Project Type Typical Board Feet Examples
Small DIY Project 10 to 50 bd ft Shelves, small furniture, repairs
Medium Project 50 to 200 bd ft Tables, cabinets, pergolas
Large Project 200 to 500 bd ft Decks, fences, small structures
Major Construction 500+ bd ft Home framing, large decks, barns

Always add 10 to 15 percent extra board feet to your calculation to account for waste, cuts, and defects in the wood.

Accuracy, Limitations & Common Mistakes of the Lumber Calculator

How Accurate Is the Lumber Calculator?

The calculator provides accurate board feet estimates when you enter actual lumber dimensions. The formula is the same one used by lumber yards and sawmills across North America. Results are based on the standard board foot definition of 144 cubic inches of wood. However, the calculator cannot predict waste factors or account for defects in individual boards.

Limitations of the Lumber Calculator

This calculator does not account for lumber waste from cutting, defects like knots or splits, or the difference between nominal and actual dimensions. Nominal sizes are what lumber is called, while actual sizes are what you measure. A "2x4" is actually 1.5 by 3.5 inches. The calculator also cannot factor in kerf loss from saw blades or moisture content, which affects weight and shrinkage.

Common Mistakes to Avoid

  • Using nominal sizes instead of actual dimensions. A "1x6" board is actually 0.75 inches thick and 5.5 inches wide. Always measure or look up actual sizes for accurate results.
  • Forgetting to add extra for waste. Most projects need 10 to 15 percent more lumber than the exact calculation shows. This covers cutting errors and unusable sections.
  • Mixing up feet and inches. Enter length in feet but width and thickness in inches. Double-check your units before calculating.

Frequently Asked Questions

Who is this Lumber Calculator for?

This calculator is for woodworkers, contractors, DIY enthusiasts, and anyone who needs to estimate lumber volume. It works for both softwood construction lumber and hardwood for fine woodworking. Use it when planning projects, creating material lists, or comparing lumber prices.

How often should I use this calculator?

Use this calculator whenever you plan a new project, request quotes from lumber suppliers, or need to estimate material costs. It is helpful during the planning phase and when adjusting designs that change lumber requirements.

Does this calculator work for all types of lumber?

Yes, the board feet formula works for all types of lumber including softwood, hardwood, and engineered wood products. However, some engineered products like plywood are sold by the sheet rather than board feet. Check how your supplier prices specific materials.

Can I use this calculator for metric measurements?

This calculator uses US customary units only. For metric measurements, you would need to convert dimensions first or use a cubic meter calculator. One board foot equals approximately 0.00236 cubic meters.

Is the Lumber Calculator free to use?

Yes, this calculator is completely free with no sign-up required. It works on any device with a web browser.

References

  • United States Department of Agriculture, Forest Service - Wood Handbook: Wood as an Engineering Material
  • National Hardwood Lumber Association - Rules for the Measurement and Inspection of Hardwood and Cypress
  • American Lumber Standard Committee - American Softwood Lumber Standard

Calculation logic verified using publicly available standards.

View our Accuracy & Reliability Framework →