Board Foot Calculator

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Board Foot Calculator
Calculate Total Board FeetCalculate Board Feet and Total Cost
Results:
function calculateBF(){var t=parseFloat(document.getElementById('thickness').value);var w=parseFloat(document.getElementById('width').value);var l=parseFloat(document.getElementById('length').value);var q=parseFloat(document.getElementById('quantity').value);var p=parseFloat(document.getElementById('price').value);var showSteps=document.getElementById('steps').checked;var ansDiv=document.getElementById('answer');if(isNaN(t)||isNaN(w)||isNaN(l)||isNaN(q)){ansDiv.innerHTML='Please enter valid numbers for thickness, width, length, and quantity.';ansDiv.style.display='block';return;}var bfSingle=(t*w*l)/12;var bfTotal=bfSingle*q;var resultHTML='
Board Feet: '+bfTotal.toFixed(2)+' BF
';if(!isNaN(p)){var totalCost=bfTotal*p;resultHTML+='
Total Cost: $'+totalCost.toFixed(2)+'
';}if(showSteps){resultHTML+='
';resultHTML+='Step-by-Step:
';resultHTML+='1. Formula: (Thickness" × Width" × Length\') / 12
';resultHTML+='2. ('+t+' × '+w+' × '+l+') / 12 = '+bfSingle.toFixed(2)+' BF per board
';resultHTML+='3. '+bfSingle.toFixed(2)+' BF × '+q+' pieces = '+bfTotal.toFixed(2)+' total BF';if(!isNaN(p)){resultHTML+='
4. '+bfTotal.toFixed(2)+' BF × $'+p.toFixed(2)+' = $'+(bfTotal*p).toFixed(2);}resultHTML+='
';}ansDiv.innerHTML=resultHTML;ansDiv.style.display='block';}

How to Use the Board Foot Calculator

The board foot calculator is an essential tool for woodworkers, carpenters, and DIY enthusiasts to estimate the volume of lumber needed for a project. Unlike square footage or linear footage, board feet measure volume, which is critical when buying rough-sawn lumber or hardwoods.

To use this calculator, follow these simple steps:

Thickness (Inches)
Enter the nominal or actual thickness of the wood in inches. In hardwoods, this is often expressed in quarters (e.g., 4/4 is 1 inch, 8/4 is 2 inches).
Width (Inches)
Enter the width of the board in inches.
Length (Feet)
Enter the length of the board in feet. This is the standard measurement unit for lumber length in North America.
Quantity
If you are buying multiple boards of the same size, enter the total number of pieces.

Board Foot Formula

A board foot is defined as a volume equal to a board that is 12 inches wide, 12 inches long, and 1 inch thick. This equals 144 cubic inches. When calculating board feet, we use the following standard formula:

Board Feet (BF) = (Thickness" × Width" × Length') / 12

If all your measurements are in inches, you can use this alternative formula:

Board Feet (BF) = (Thickness" × Width" × Length") / 144

Lumber Calculation Example

Scenario: You are building a tabletop and need 5 boards of Walnut. Each board is 2 inches thick, 8 inches wide, and 10 feet long. The price for Walnut is $9.50 per board foot.

Step-by-step solution:

  1. Thickness = 2″
  2. Width = 8″
  3. Length = 10′
  4. Quantity = 5
  5. Calculate single board: (2 × 8 × 10) / 12 = 13.33 BF
  6. Total volume: 13.33 × 5 = 66.65 BF
  7. Total cost: 66.65 × $9.50 = $633.18

Common Questions

What is the difference between nominal and actual size?

Nominal size is the name given to the lumber before it is surfaced (planed smooth). For example, a "2×4″ is the nominal size, but the actual size is usually 1.5″ x 3.5". When using a board foot calculator for rough lumber, use the nominal dimensions. For finished projects, use the actual dimensions to ensure you have enough volume.

Why is board footage used instead of linear feet?

Linear footage only measures length, ignoring width and thickness. Since hardwood logs come in various widths and thicknesses, sellers use board feet to charge for the actual volume of wood material you are receiving, ensuring fair pricing regardless of board shape.

How do I calculate waste?

It is industry standard to add 15% to 20% to your total board foot calculation to account for knots, cracks, and sawdust waste. To do this, multiply your final board foot result by 1.20.

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