Construction

Paint Calculator

Calculate paint gallons, square footage coverage, and primer coats for rooms and exterior walls.

Reviewed & Maintained by

Aadil Malik — Software Engineer

1 min read · 27 words

What is a Paint Calculator?

A paint calculator computes total wall and ceiling surface area and determines the exact number of paint gallons or liters needed.

Frequently Asked Questions

One standard gallon (3.78 liters) of paint covers approximately 350 to 400 square feet with a single coat on smooth primed walls.

Two coats provide optimal color depth, uniform finish, and durable coverage.

Subtract ~20 sq ft per standard door and ~15 sq ft per standard window from total wall area.

Primer is required on bare drywall, unpainted wood, stained surfaces, or when transitioning from a dark color to a light color.

Matte/Flat hides imperfections (ceilings); Eggshell/Satin offers gentle sheen and easy cleaning (living rooms, bedrooms); Semi-Gloss resists moisture (bathrooms, kitchens, trim).

Ceiling Area = Room Length * Room Width.

Yes. Heavily textured walls (orange peel, knockdown) require 20%–30% more paint.

Latex paint typically dries to touch in 1 hour and can be recoated in 2 to 4 hours.