Paint Cost Calculator: Gallons and Material Budget
Estimate paint quantity and an approximate material budget using your wall area, number of coats, product coverage, allowance and current price per gallon.
Formula
Gallons = ((paintable area × coats) ÷ coverage per gallon) × (1 + allowance %). The budget shown multiplies the rounded gallon count by your entered price.
Use the coverage on the actual paint
Coverage changes with surface porosity, texture, application method and color change. Replace the default with the coverage printed by the manufacturer for the product you plan to use.
Worked example
For 800 sq ft, two coats, 400 sq ft per gallon and 10% allowance, the calculated quantity is 4.4 gallons. Planning with whole 1-gallon units gives 5 gallons. At $45 per gallon, the approximate paint-only budget is $225.
Costs not included
Primer, patching materials, tape, rollers, brushes, trays, tax and labor are not included. If your retailer sells 5-gallon pails or other package sizes, compare package combinations rather than relying only on the rounded gallon count.
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Planning estimate only. Use current product coverage, package sizes and prices before purchase. Editorial review: October 2026.