Deck Board Calculator — Free Online Tool

How to use the Deck Board Calculator

Calculate the number of deck boards required for straight, full-length board courses with customizable actual board width, installation gap, stock length and waste.

1. Measure across the board courses and along the direction boards will run.
2. Enter the actual finished face width, not the nominal labeled board dimension.
3. Set your board spacing and stock board length.
4. Add cutting waste and inspect the resulting course count and stock-board quantity.

Accuracy note: Single-board-per-course planning only. Use local building requirements for structural design.

Deck Board Calculator formula and method

Board courses = ceil((deck width + gap) ÷ (actual board face width + gap)). Stock boards required = ceil(courses × (1 + waste percentage)) for a layout using one stock board per course.

All numeric results depend on entered measurements, dimensions and settings. Intermediate calculations retain decimal precision; displayed results may be rounded. Verify material specifications, relevant laws and seller fee conditions where applicable.

Worked example

With a 12-foot deck width, 5.5-inch actual board face width and 1/8-inch gap, roughly 26 parallel board courses are required. A 16-foot deck length requires 16-foot stock boards when each course is one piece.

Adjust the values in the interactive tool above to reproduce this example or model your own situation.

Frequently asked questions