Shade Coverage Calculator

Shadow Length is calculated as tree height divided by the tangent of the Sun Angle, and the tangent of a small angle is itself small — so dividing by it produces a large result. This is the same reason your own shadow stretches out long near sunrise and sunset (when the sun sits low on the horizon) and shrinks to almost nothing near solar noon (when the sun is high overhead).

This calculator applies a modest overlap discount (15%) whenever more than one tree is providing shade, on the assumption that trees planted for combined shade coverage are close enough together that their shadows partially overlap rather than falling on entirely separate ground. A single isolated tree gets its full calculated shadow area with no discount; grouped trees get slightly less than the simple sum to avoid overstating the total shaded footprint.

An earlier version of this calculator collected a Latitude value but never actually used it in any calculation — Sun Angle already captures exactly what latitude and time of year would otherwise be used to estimate, so the unused field was removed rather than left as a misleading input. Enter the Sun Angle you want to model directly (lower for morning/evening/winter, higher for midday/summer) instead.

This output is a coarse energy-savings ballpark, not a guaranteed utility-bill reduction: it applies this calculator's own simplified rate (roughly $2 per 100 square feet of shade per summer month), which we could not verify against one specific authoritative source, so treat the exact dollar figure as illustrative rather than a sourced statistic. It also doesn't account for which side of your home the shade falls on, your local climate and cooling-degree-days, your home's insulation and window efficiency, or how much of the day that shade actually covers windows and walls versus open yard.

UV Reduction is reported as a single fixed estimate (roughly what's commonly described for a mature, healthy, full canopy) rather than scaling with Tree Height, Canopy Spread, Sun Angle, or Number of Trees, because real UV blocking depends primarily on canopy density — how full and leafy the tree actually is — not on how wide or tall it is. This calculator has no input that measures density, so rather than derive a false sense of precision from an input that doesn't actually drive real-world UV blocking, it reports one honestly-hedged illustrative figure. It is not complete protection either way: scattered and reflected UV still reaches shaded ground, canopy density varies by species and season, and this output is meant to inform landscaping and energy decisions, not to replace sunscreen or other sun-safety precautions.