Stain & Sealer Coverage Calculator

Stain and sealer coverage varies more than paint coverage because these products soak into the substrate rather than sitting on top of it, so this calculator adjusts your product's rated coverage (sq ft/gallon on smooth surfaces) downward using two multipliers before computing gallons needed. The surface-type multiplier reflects how much a substrate absorbs: smooth wood is the baseline (1.0×), rough-sawn wood absorbs 30% more product (1.3×), and concrete or masonry absorbs 50% more (1.5×). The porosity multiplier layers on top, adding 15% more consumption per porosity level above the lowest setting — so a highly porous surface like raw cedar or open-pore concrete can combine both multipliers to consume nearly double the base coverage rate — up to 1.95× at the calculator's maximum surface-type and porosity settings.

Effective coverage is the rated coverage divided by the product of both multipliers, gallons per coat is area divided by that effective coverage, and total gallons needed rounds up from gallons-per-coat times the number of coats specified. Application time uses a separate fixed rate by surface type (200/150/100 sq ft/hr for smooth wood, rough wood, and concrete respectively) multiplied by the number of coats, while total project time adds fixed dry-time gaps between coats (2/4/6 hours depending on surface type) since each coat must cure before the next goes on. A common mixup: the "base coverage" input should come from the product's smooth-surface rating on the label, not an already-adjusted estimate — this calculator applies its own absorption penalty, so entering a pre-adjusted number will double-count the effect and overestimate how much product you need.