Paint Calculator

This Paint Calculator precisely estimates the gallons of paint required to refresh any room, factoring in common architectural elements like doors and windows, and your desired number of coats. In 2026, with premium interior latex paint averaging $45-$60 per gallon and labor costs escalating, accurate estimation is crucial to avoid costly over-purchasing or frustrating mid-project supply runs.

The calculator determines total wall surface area by summing (Room Length * Room Height * 2) + (Room Width * Room Height * 2). It then subtracts the area of all doors (Door Width * Door Height) and windows (Window Width * Window Height) to yield the net paintable area. This net area is then multiplied by the number of desired coats and divided by the paint's coverage rate (typically 350-400 sq ft per gallon for a single coat).

Always round up to the nearest whole gallon to ensure sufficient supply, as paint sheen and surface texture can affect actual coverage. Don't forget to account for primer if painting over a dark color or unfinished drywall; this often requires a separate calculation or an additional coat. Neglecting to measure accurately is the most common mistake, leading to significant waste or delays.