Spray Equipment Calculator

Flow rate through an orifice scales with the orifice's cross-sectional area (proportional to tip size squared) but only with the SQUARE ROOT of pressure, so a given percentage increase in tip size moves flow rate far more than the same percentage increase in pressure does. That's why sprayer manufacturers publish flow-rate-by-tip-size charts as the primary sizing reference, with pressure adjusted within a narrower range mainly to dial in atomization quality rather than to control total output.

Coverage rate (square feet per gallon) is a manufacturer-rated efficiency figure -- a higher number means one gallon spreads over more area, so covering the same total job area requires proportionally fewer gallons. A coating with a lower coverage rate (thicker application, more porous substrate, or a less efficient formulation) needs correspondingly more gallons to cover the identical square footage.

Treat it as a planning estimate, not a precise prediction -- overspray in real spraying depends on gun technique, distance from the surface, ambient wind, tip wear, and the specific coating's atomization behavior, none of which this calculator can observe. It's useful for ballpark material ordering and comparing scenarios, but a professional estimate or your own historical waste rate on similar jobs will be more accurate for a specific project.

Check the manufacturer's thinning chart for that specific product whenever one is available -- viscosity-based thinning guidance like this calculator's is a reasonable starting estimate, but different coating chemistries (latex, oil-based, specialty industrial coatings) thin differently, and over-thinning can cause sagging, reduced film build, or adhesion problems that a generic Krebs-unit rule of thumb can't account for.