Pervious Concrete Calculator

Infiltration Rate (in/hr) depends only on Void Ratio (%) -- it is a simplified linear model, infiltration equals void ratio times 14.4 -- so Pavement Area, Thickness, and Design Rainfall never move this number at all. Estimated Cost follows the same one-input pattern from the opposite side: it is simply Pavement Area times a flat $11/sq ft installed rate, unaffected by thickness, void ratio, or rainfall design. Within this calculator's declared ranges (15-35% void ratio, 0.1-10 in/hr design rainfall), Infiltration Rate always works out to at least 216 in/hr, far above any design rainfall intensity the tool accepts, so Handles Design Storm reads Yes for every combination of inputs you can enter -- a No would require rainfall intensities far beyond typical design-storm values.

Storage Capacity (cu ft) and the gallon figures scale with both Pavement Area and Thickness together, since they measure the volume of void space available in the slab -- doubling either one doubles storage. Runoff Reduction (%) responds most strongly to Design Rainfall: at low rainfall intensities the pavement's fixed storage capacity absorbs nearly all of it (100% reduction), but as rainfall intensity climbs toward the top of the design range, that same fixed storage handles a shrinking share of total runoff. This tool does not model clogging over time, which reduces real-world infiltration rates significantly.