How to Calculate Paint Coverage Like a Pro
Nothing stalls a home renovation project faster than running out of paint mid-wall. Conversely, buying three extra gallons of a custom-mixed color is a waste of money and shelf space. This paint coverage calculator is designed to take the guesswork out of your next project. By factoring in the length, width, and height of your room, and accounting for non-paintable areas like doors and windows, we provide a precise estimation of the volume of liquid paint needed to complete your job.
Factors That Affect Your Paint Needs
- Surface Texture: Smooth, primed drywall will use much less paint than textured plaster, brick, or unprimed wood. Porous surfaces "drink" the liquid, requiring more volume.
- Color Change: If you are painting a light color over a dark one, you will almost certainly need two or more coats for proper opacity.
- The "Number of Coats" Rule: While many modern paints claim "one-coat coverage," professionals almost always apply two. The first coat seals the surface, while the second provides the final depth of color and uniform sheen.
Measuring Non-Paintable Areas
A standard interior door is approximately 20 square feet, and a standard window is roughly 15 square feet. In a typical room with two windows and one door, you are removing 50 square feet of area. That is nearly 15% of a standard gallon's coverage! Our calculator automates these subtractions to ensure your estimate is as lean and accurate as possible.
Frequently Asked Questions
How much does one gallon of paint cover?
As a general industry standard, one gallon of quality interior paint covers approximately 350 to 400 square feet with a single coat. For a typical bedroom requiring two coats, you should plan for two gallons.
Should I buy an extra quart just in case?
It is always wise to have a small amount of leftover paint for future touch-ups. If our calculator estimates you need 1.1 gallons, it is better to buy two gallons than to risk a color mismatch by buying a quart later from a different batch.