Varnish Coverage Calculator

Varnish volume scales with painting area, number of coats, and how efficiently your chosen product and application method transfer onto canvas — this calculator combines all three using a lookup table of coverage rates (square feet of coated surface per fluid ounce) that differ by both varnish type and method: spray application uses more product per square foot than brushing on every combination, because overspray is lost to the air, while among the three products acrylic covers most efficiently per ounce, damar (the traditional resin) sits in the middle, and Gamvar covers least efficiently. It multiplies your painting's area by the number of coats and the number of paintings to get total area to cover, divides by the coverage rate to get raw ounces needed, then adds a 10% allowance for edge bleed and waste. That figure converts to milliliters and gets matched against standard bottle sizes (4, 8, 16, or 32 fl oz) to recommend the smallest bottle that covers your job without running short mid-coat.

Estimated cost applies a rough per-ounce price by varnish type, and total dry time between coats multiplies the number of gaps between coats by a fixed recoat window for your varnish (damar and Gamvar need roughly a full day between coats; acrylic varnish is ready again in about two hours). Keep in mind these are typical figures — actual coverage varies with brush technique, canvas texture and absorbency, and ambient humidity, so treat the bottle recommendation as a floor and keep a little extra on hand for a large or heavily textured piece.