Use this deck board spacing calculator to plan the layout before fastening. Enter the clear field width, actual board width, and gap for the exact decking system, then solve an even gap or split the leftover width across both edge boards.
How the board layout is solved
Both modes close the measured field exactly, but they make different finish decisions.
Worked example
- Across 144 , 25 full 5.5 boards need 24 gaps of 0.270833 .
- If a 3/16 product gap must stay fixed, 26 work when both edge boards are ripped to 3.65625 .
Use the gap for your exact decking system
Spacing is a product and installation input, not a universal calculator constant. Confirm the exact guide before choosing between a changed even gap and fixed-gap edge rips.
Full boards or equal edge rips
Full boards preserve board width and solve the spaces. Equal edge rips preserve every entered gap and split the remaining board width evenly at the two edges. The result and warning make that tradeoff explicit before the first board is fastened.