How this works
boards = ceil( board feet × (1 + waste%) ÷ BF per board )
Each board's volume is thickness × width × length ÷ 144. Divide what the project needs — plus waste — by that, and round up, because the yard doesn't sell 5.3 boards.
Real boards come in random widths, so treat this as a buying estimate: pick the width your yard actually stocks in quantity. For part-by-part planning with species pricing, use the planner.