Utility
Paint Calculator
Calculate exactly how much paint you need for your room based on dimensions, doors, windows, and coats.
Enter room dimensions and click Calculate
How is this calculated?
Perimeter = 2 × (Length + Width)
Total Wall Area = Perimeter × Height
Paintable Area = Total - (Doors × 21 sqft) - (Windows × 15 sqft)
Paint Needed = (Paintable Area × Coats) / 350 sqft per gallonFAQ
Frequently asked questions
How much paint do I need for a room?
Calculate total wall area (perimeter × height), subtract doors (21 sq ft each) and windows (15 sq ft each), then divide by paint coverage (typically 350 sq ft per gallon). Multiply by number of coats.
How much area does one gallon of paint cover?
One gallon of standard interior paint covers approximately 350-400 square feet per coat on smooth surfaces. Textured walls or porous surfaces may require more paint (250-300 sq ft/gallon).
How many coats of paint do I need?
Two coats is standard for most projects. Use one coat with paint-and-primer-in-one over similar colors. Three coats may be needed when covering dark colors with light ones.
Should I subtract doors and windows?
Yes, subtract standard door area (about 21 sq ft each) and window area (about 15 sq ft each) from total wall area. This gives a more accurate paint estimate and saves money.
How do I calculate paint for a ceiling?
Ceiling area is simply length × width of the room. Use the same coverage rate (350 sq ft/gallon) and plan for 2 coats. Ceiling paint is typically thicker to reduce dripping.
Is this paint calculator free?
Yes, completely free with no sign-up. All calculations happen in your browser — your data is never sent to any server.