Deck surface board quantity

What this calculation does

A deck surface estimate counts straight rows across a measured rectangle after the board face width and chosen gap are specified.

Measure the dimension across rows and along each board, then enter the actual board face width and the gap chosen for the product.

Enter the measurements

1. Deck depth across the board rows: Measure the deck dimension across board rows.
2. Deck run along each board: Measure the length of one full row.
3. Measured board face width: Use the installed face width, not a nominal label.
4. Chosen gap between boards: Enter the gap selected for the specific decking.

Formula and variables

Rows = ceil((deck depth + chosen gap) ÷ (board face width + chosen gap)). Final-row width = deck depth − (rows − 1) × (board face width + chosen gap). Linear feet = rows × deck run.

The row count rounds up to cover the depth. The last-row width is the remaining depth after the preceding full boards and gaps.

Read the result

The surface takes 22 rows and 264 linear feet before cuts or waste; the final row is 1.875 in wide before trimming.

Worked example

Inputs: 120 in deck depth, 12 ft run, 5.5 in board faces and 0.125 in chosen gap

1. Rows = ceil((120+0.125)÷(5.5+0.125)) = 22.
2. Final row = 120−21×5.625 = 1.875 in; footage = 22×12 = 264 LF.

Expected result: 22 rows, 264 linear ft and 1.875 in final-row width