Shade Structure Calculator

A shade structure is mounted at a fixed point, but the sun's position moves across the day and the seasons, so the ground shadow it casts shifts around under it. To reliably keep the Target shade area (sq ft) covered through that shift, the physical canopy has to extend beyond the target footprint by a shadow-offset margin -- which is why Required canopy area (sq ft) always comes out larger than the raw target you entered.

This calculator estimates summer-solstice solar altitude from latitude (roughly 90 minus latitude plus 23.5 degrees), and a lower solar altitude casts a longer shadow for the same Mounting height (ft). Higher-latitude sites (Seattle at 47 degrees, for example) have a lower summer sun angle than lower-latitude sites (Miami at 26 degrees), so the same structure needs more overhang -- and therefore more canopy area -- the farther north or south of the equator the site sits.

Yes -- a taller structure casts a longer shadow at any given sun angle (shadow offset scales directly with mounting height divided by the tangent of the solar altitude), so Required canopy area (sq ft) increases as Mounting height (ft) increases, holding Site latitude and everything else fixed. A structure mounted at the maximum 20 ft needs noticeably more overhang than one at the minimum 8 ft.

Structure type only changes which cost-per-square-foot rate and maximum single- span size apply when converting canopy area into Structures needed, Support posts, and Estimated cost ($) -- it does not feed into the geometry that determines how much area needs shading in the first place. Target shade area (sq ft) and Required canopy area (sq ft) are set entirely by Play area (sq ft), Shade coverage target (%), Mounting height (ft), and Site latitude.