Square Feet to Board Feet Calculator
Enter the area you need to cover (in square feet).
Thickness is in inches. “4/4” is often treated as 1" for quick estimates.
Result
100.00
BF
With 15% waste: 115.00 BF
Formula: 100.00 = 100.00 × 1.00
Convert square feet to board feet based on board thickness. Choose a common thickness (4/4, 6/4, 8/4) or enter a custom value.
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Quick Conversion Table
Common areas at popular thicknesses. Tap a row or column to highlight.
| Square Feet | 1" (4/4) | 1.5" (6/4) | 2" (8/4) |
|---|---|---|---|
| 10 sq ft | 10.00BF | 15.00BF | 20.00BF |
| 25 sq ft | 25.00BF | 37.50BF | 50.00BF |
| 50 sq ft | 50.00BF | 75.00BF | 100.00BF |
| 100 sq ft | 100.00BF | 150.00BF | 200.00BF |
| 200 sq ft | 200.00BF | 300.00BF | 400.00BF |
| 500 sq ft | 500.00BF | 750.00BF | 1000.00BF |
Tip: Thicker boards need more BF to cover the same area.
How to Convert Square Feet to Board Feet
Multiply area by thickness (in inches).
- 1
Step 1 — Enter square feet
Input the surface area in square feet you need to cover.
- 2
Step 2 — Choose thickness
Select a common thickness like 4/4 (1"), 6/4 (1.5"), or 8/4 (2"). You can also enter a custom thickness.
- 3
Step 3 — Read the result
Board Feet = Square Feet × Thickness. Add 10–15% extra for waste if you’re buying material.
Understanding the Units
Square feet is area; board feet is volume (including thickness).
What is a board foot?
A board foot is a volume unit: 144 cubic inches (1" × 12" × 12"). Lumber is often priced by BF.
What is a square foot?
A square foot measures surface area (12" × 12"). It’s used for coverage like flooring and decking.
Why convert?
If you know the area you need to cover, converting helps you estimate how much lumber to buy.
Square Feet → Board Feet Formula
Thickness is the only extra input because board feet includes volume.
| Symbol | Meaning | Unit |
|---|---|---|
| BF | Board feet | BF |
| Square Feet | Area to cover | sq ft |
| Thickness | Board thickness | in |
Example: 100 sq ft × 1" = 100 BF.
Real-World Examples
Two quick conversions with common thicknesses.
| Input | Output | Notes |
|---|---|---|
| 100 sq ft at 3/4" (0.75") | 75 BF | 100 × 0.75 = 75 |
| 250 sq ft at 1.5" (6/4) | 375 BF | 250 × 1.5 = 375 |
Common Mistakes to Avoid
Quick fixes that keep your estimate realistic.
Forgetting waste
Add 10–15% extra for waste, especially for flooring layouts, knots, and trimming.
Using the wrong thickness
Hardwood “quarters” are naming conventions. If your supplier lists actual thickness, use that value instead of the nominal quarter value.
Mixing area and volume units
Square feet is area. Board feet is volume. Thickness is what links them—if thickness changes, BF changes even if area stays the same.
Disclaimer
This calculator provides an estimate for planning. Calculations are estimates. Add 10–15% for waste. Always confirm quantities and actual thickness with your lumber supplier.
Sources
- Board foot definition: 12" × 12" × 1" = 144 cubic inches.
- Hardwood thickness naming: quarters (4/4, 5/4, 6/4, 8/4) are common lumber yard conventions.
- Woodworking education resources and extension guides for lumber measurement.
Frequently Asked Questions
Use: Board Feet = Square Feet × Thickness (inches). Thickness is the only extra input because board feet includes thickness.
Pro tip
When buying lumber, add 10–15% extra for waste (cuts, defects, and mistakes) so you don’t run short.