A how many boards do i need calculator works from one figure a sheet calculator never needs: the coverage width, the width of one board plus the gap or overlap beside it, because boards are laid side by side and the gap is part of the pattern. The count is the run to be covered divided by that coverage width, rounded up, and the pieces are that count at the length the boards come in, with the joints where a run is longer than a board. This page works a deck, a fence and a wall of siding boards, says where the coverage width comes from for each, and prices the result on the lumber cost calculator arithmetic the board foot page on this site describes. The construction cost estimator prices the order at the yard's rate.
The deck: run over the coverage width, and the joists it needs
A 16 by 12 deck with boards running the 16 foot way covers 12 feet of run. A deck board's coverage width is its actual face width plus the gap the boards are laid with, and 12 feet, 144 inches, divided by that coverage width, rounded up, is the board count across the deck; each board is a 16 foot piece, or two 8 foot pieces with the joint on a joist. The waste is the last board ripped to fit and the cut-offs at the ends. The wood handbook linked below gives the actual dimensions of nominal lumber, which is why the coverage width is worked from the actual face and not the nominal size on the bin.
The fence: pickets by the coverage width, rails by the run
A fence run of 60 feet with pickets set with a gap has a picket count of 720 inches over the picket's coverage width, face plus gap, rounded up. Board-on-board or overlapping styles have a smaller coverage width per board because each board hides part of the next, and the count rises accordingly. The rails are by the run, two or three per section between posts, and the posts by the spacing. A fence calculator that counts pickets and forgets the rails and posts is half a list; this one carries the three lines separately, each at its own length.
The wall: siding boards by the exposure
Lap siding covers a wall by its exposure, the part of each board left visible below the board above, so the coverage width is the exposure, not the board's width, and the count is the wall's height over the exposure, rounded up, times the runs across the wall's length at the board's length with the joints staggered. On the worked house's 140 feet of exterior wall at 8 feet, the height over the exposure gives the courses, and each course is 140 feet of board at the yard's lengths. The residential code's wall covering chapter, linked below, is where the exposure and fastening rules the manufacturer's instructions sit under live.
The lumber cost calculator: pieces to board feet to the line
Each line is pieces at a length, and the yard prices by the piece or by the board foot. The board foot calculator on this site converts: thickness times width times length in inches over 144 per piece, times the count. The deck's boards, the fence's pickets, rails and posts, and the siding's courses each become a board-foot figure and a price at the yard's rate, and the construction cost estimator on this site prints them as lines. NIST Handbook 44, linked below, is the reason the board foot on the invoice is a defined quantity. DrawScheduleWorks Pro keeps the order against the job so the delivery can be checked against the count.
Questions people ask about how many boards do i need calculator
How do I calculate how many boards I need?
Divide the run to be covered by the board's coverage width, its actual face plus the gap or less the overlap, and round up; each board is a piece at the length the run needs, with joints where a run is longer than a board.
What is coverage width?
The width one board covers in the pattern: face plus gap on a deck or a spaced fence, face less overlap on board-on-board, the exposure on lap siding. It is worked from the actual dimension, not the nominal size.
How are the boards priced?
Pieces at a length become board feet by thickness times width times length in inches over 144, and board feet times the yard's rate is the line. The construction cost estimator on this site prints it.