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. Getting the count right avoids both leftover cans and a mid-project supply run.

The calculator determines total wall surface area by summing (Room Length * Room Height * 2) + (Room Width * Room Height * 2). It then subtracts a standard 21 sq ft for each door and 15 sq ft for each window 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 (350 sq ft per gallon by default; use the figure on the can). The cost line prices the rounded-up gallons at a fixed $35 a gallon.

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.