Paint quantity equals coated area times coat count divided by the selected product's practical coverage per gallon. Measure each surface, deduct only meaningful exclusions, and use the product data rather than assuming every coating covers the same area.
Multiply net paintable area by coat count, divide by the selected coating's practical square-foot coverage per gallon, and round to available container sizes.
Published: September 20, 2026
Last reviewed: September 20, 2026
Published by BuildYard. The guide reflects BuildYard's calculation methodology and editorial standards and does not replace project-specific professional advice.
For walls, combine wall length times height and treat ceilings separately when products differ.
Subtract large doors or openings only when doing so improves the takeoff rather than creating false precision.
Two coats require twice the one-coat theoretical area before coverage conversion.
Primer is a separate product and should be estimated separately when required.
Coverage varies by coating, application method, texture, color change, and surface condition.
Use the exact product specification or manufacturer guidance for final purchasing.
Roller loading, brush work, spray loss, porous surfaces, and touch-up can affect consumption.
Keep reserve separate from coat count and net area.
Convert calculated gallons into available gallon and five-gallon containers.
Verify substrate preparation, temperature, recoat time, sheen, and compatibility separately.
BuildYard example using 350 sq ft/gal, the lower end of Sherwin-Williams' typical 350–400 sq ft/gal guidance.
| Step | Result |
|---|---|
| Wall area | 1,200 sq ft |
| Two-coat area | 2,400 sq ft |
| Coverage | 350 sq ft/gal |
| Calculated quantity | 6.86 gal before container rounding |
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Estimate primer gallons from net surface area, number of coats, product coverage, substrate condition, and package rounding.
Read guide →PaintEstimate paint gallons from net surface area, number of coats, product coverage, openings, substrate condition, and purchase rounding.
Read guide →Current manufacturer data, supplier specifications, drawings, field measurements, applicable codes, permit requirements, and qualified professional guidance can take priority over a general-purpose planning estimate.