Methodology

Formula, units, and scope

Convert each input to metres (1 ft = 0.3048 m). For length L and maximum spacing S, segments = max(1, ceil(L ÷ S)); posts = segments + 1; equal actual spacing = L ÷ segments. Both end posts are included. For 50 m and 3 m, 17 segments need 18 posts and the spacing is about 2.94 m. The on-page diagram is schematic, not to scale.