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Square Foot to Board Foot Calculator - Surface Area to BDFT Converter
Convert square feet to board feet (BDFT) with thickness consideration. Free bidirectional calculator for flooring, decking, and surface area lumber projects. Instant BDFT calculations.
Last updated: 1/26/2025
Conversion Direction
Square Feet (Surface Area)
Lumber Thickness
Waste Factor (Optional)
Conversion Results
Formula:
Board Feet = Square Feet × Thickness ÷ 12Example Projects:
- • 200 sq ft of 3/4" flooring = 12.5 BF
- • 300 sq ft of 1" deck boards = 25.0 BF
- • 150 sq ft of 5/8" subflooring = 7.8 BF
How to Convert Square Feet to Board Feet
Converting surface area to lumber volume is crucial for flooring, decking, and siding projects. Our calculator handles the thickness factor to give you accurate material requirements.
Measure the Area
Calculate the total square footage of the area you need to cover. For irregular shapes, break them into rectangles and add the areas together.
Know Your Thickness
Determine the thickness of the lumber you'll use. Common thicknesses include 3/4" for flooring, 1" for deck boards, and 5/8" for subflooring.
Add Waste Factor
Include 5-15% waste to account for cuts, mistakes, and odd pieces. Complex layouts or inexperienced installers should use higher percentages.
The Conversion Formula
Board Feet = Square Feet × Thickness (inches) ÷ 12
Total Board Feet = Board Feet × (1 + Waste %)
This formula converts surface area to lumber volume by factoring in the thickness dimension that square feet measurements don't include.
Common Applications
Hardwood Flooring
Calculate board feet needed for hardwood floor installation. Typically uses 3/4" thick planks with 5-10% waste factor.
Deck Construction
Determine lumber volume for deck boards and subflooring. Common thicknesses are 1" to 1.5" with 10-15% waste.
Siding Projects
Calculate board feet for exterior siding installation. Thickness varies by siding type, typically 0.5" to 1".
Subflooring
Estimate plywood or OSB subflooring needs. Common thicknesses include 5/8" and 3/4" depending on joist spacing.
Paneling & Wainscoting
Calculate material for wall paneling projects. Thickness typically ranges from 1/4" to 3/4" depending on style.
Tabletops & Counters
Determine lumber needs for large flat surfaces. Consider glue-up waste and final thickness after planing.
Frequently Asked Questions
How do you convert square feet to board feet?
To convert square feet to board feet, multiply the square feet by the thickness in inches, then divide by 12. Formula: BDFT = Square Feet × Thickness ÷ 12. For example, 100 sq ft of 1-inch thick lumber = 100 × 1 ÷ 12 = 8.33 board feet.
What's the difference between square feet and board feet?
Square feet measures surface area (length × width), while board feet measures volume (length × width × thickness). Square feet is used for area coverage, while board feet determines lumber volume for pricing and material calculations.
Can I convert board feet back to square feet?
Yes! Our calculator works both ways. To convert board feet to square feet, multiply board feet by 12, then divide by thickness: Square Feet = (Board Feet × 12) ÷ Thickness. This helps determine coverage area from known lumber volume.
When do I need to convert square feet to board feet?
This conversion is essential for flooring, decking, siding, and any project where you know the area to cover but need to calculate lumber volume for purchasing. It's particularly useful for estimating costs since lumber is sold by board feet.
What thickness should I use for common lumber applications?
Common thicknesses include: hardwood flooring (0.75"), deck boards (1" or 1.5"), plywood subflooring (0.75"), and siding (0.75" to 1"). Use actual finished thickness for accurate board foot calculations.
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