Estimate decking board count, a spacing-based joist count, and deck area. Beam, post, fastener, railing, and baluster quantities require a separate project takeoff.
Inputs and method
Enter deck dimensions, select a board size with its labeled actual face width, and enter joist spacing and waste. Board count spans the deck width and applies waste before a whole-board ceiling; joist count is a spacing-based geometric count.
Calculations retain full floating-point precision until the labeled display step. Counts and packages use an explicit upward ceiling only where a whole purchase unit is required.
Interpreting the estimate
Use the result as a planning value and keep input precision consistent with the measurements or source data you have. Small displayed differences can come from final-place rounding; intermediate values are not rounded.
Assumptions and limits
This tool does not select spans, beams, posts, fasteners, guards, or structural details and does not determine code compliance. Confirm layout and product requirements separately. For deck stair stringers, use the stair calculator; for on-center joist layout, see the stud spacing calculator; and for the footing piers the deck bears on, use the concrete calculator.
Rejecting empty, invalid numeric, prohibited negative, zero-denominator, impossible, or unsupported inputs prevents the page from presenting a misleading numeric result.
Keep board direction with the estimate
Record the deck dimensions and intended board orientation before using the count. The current estimate relates deck width to board width and deck length to joist spacing; it is not a cut list. Compare waste allowances after fixing that layout, and verify available board lengths separately before ordering.