About this Decking Boards
Building a deck is a major project. Ordering the right amount of lumber saves money and frustration. This tool converts your deck's square footage into linear feet of decking boards, accounting for the width of the board and the gap between them.
Who this calculator is for
- Homeowners estimating deck-board quantities before ordering materials.
- Carpenters comparing board lengths for a new deck or resurfacing project.
- Builders planning linear footage for wood or composite decking layouts.
When to use it
- Convert deck square footage into total board linear feet.
- Estimate how many 12-foot or 16-foot boards to buy.
- Compare how different board widths or gap spacing affect material totals.
How to use this calculator
- Enter the Deck Area (Length x Width).
- Enter the Board Width (e.g., 5.5 inches for a standard 6-inch nominal board).
- Enter the Gap Size (usually 1/8 inch).
- The result is the total Linear Feet needed.
Key assumptions
- Deck area is already measured in square feet and represents the finished surface.
- Board width must be positive, and gap size can be zero or greater in inches.
- The estimate includes a built-in 10% waste allowance for cuts and defects.
Accuracy and testing
Review formula sources, default test cases, assumptions, unit handling, rounding rules, and changelog for this calculator.
How this calculator works
1. Effective Width = Board Width + Gap Size.
2. Linear Feet = (Deck Area × 12) / Effective Width.
3. Adds a 10% waste factor for cuts and defects.
Inputs explained
Board Width
The actual width, not nominal. A '6 inch' deck board is usually 5.5 inches wide.
Gap Size
The spacing between boards for drainage and expansion. 1/8 to 1/4 inch is standard.
Understanding your results
The Linear Feet tells you the total length of material. To find how many 12ft boards to buy, divide the Linear Feet by 12.
Example scenarios
10x10 Deck
100 sq ft. 5.5" boards. 1/8" gap. Needs ~235 linear feet (or ~20 boards of 12ft length).
Key Features
- Gap Spacing Logic
- Actual vs Nominal Awareness
- Waste Factor Inclusion
Tips & Best Practices
- Always use 'Actual' dimensions. Nominal 2x6 is actually 1.5" x 5.5".
- Composite decking expands and contracts. Follow manufacturer gap guidelines strictly.
- Add 10-15% waste for diagonal patterns as they require more cuts.
Glossary of Terms
- Linear Foot
- A measure of length (12 inches) regardless of width or thickness.
- Nominal Size
- The name of the lumber size (e.g. 2x6) before drying and planing.
- Hidden Fasteners
- Clips installed between boards that create a consistent gap automatically.