Calculator 05 / Paint

Paint Calculator

Estimate gallons of paint needed for a room's walls, based on coverage rate and number of coats.

How this calculator works

Wall area (ft²) = Perimeter (2 × (L + W)) × Wall height − Openings Ceiling area (ft²) = Length × Width (only if included) Paintable area = Wall area + Ceiling area Gallons needed = ceil( (Paintable area × Coats) ÷ Coverage rate )

Do I need less paint for a second coat?

Usually not — a second coat covers the same area, so this calculator multiplies total area by the number of coats rather than reducing coverage for later coats.

What if I need less than a full gallon?

If your total comes in under a gallon, most stores sell quarts (¼ gallon) — round up to the nearest quart instead of buying a full gallon.

Estimates only. Coverage rates vary by paint brand, surface texture, and application method — check the product label for the exact rate.