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Deck Board Calculator

Find how many deck boards you need for a given deck area.

Inputs

Saved Scenarios

— select 2+ to compare

Boards Needed

41

Spark says

How it's calculated

Formula

Boards=⌈Deck AreaBoard Widthft×Board Length×(1+Waste%)⌉Boards = \lceil \dfrac{Deck\ Area}{Board\ Width_{ft} \times Board\ Length} \times (1 + Waste\%) \rceil
Board\ Width_{ft}
— Board width converted from inches to feet

What is the Deck Board Calculator?

This calculator divides deck area by the coverage of one board (width × length), then adds a waste allowance for angled cuts, staggered seams, and mistakes.

How to use it

  1. 1 Enter the total deck area.
  2. 2 Enter the board's width and length.
  3. 3 Enter a waste allowance percentage.

Worked examples

200 sq ft deck, 5.5"×12ft boards, 10% waste

About 41 boards needed.

Try it

Limitations

  • •Doesn't account for gapping between boards (typically 1/8-1/4 inch for drainage) — this slightly reduces actual coverage per board versus its nominal width.

Frequently asked questions

Why leave gaps between deck boards?

Gaps allow water drainage and accommodate wood's natural expansion and contraction with humidity — skipping them can cause boards to buckle.