Multiple Rooms Paint Calculator
Free multiple rooms paint calculator — estimate paint for a whole home from room count and average size.
Runs entirely in your browser — room sizes and coverage figures never leave this pageTry: Number of rooms=3, Average room length=12, Average room width=12, Wall height=8, Doors per room=1, Windows per room=1, Coverage per gallon=350, Number of coats=2, Waste factor=15 → 3, 348 sq ft, 1044 sq ft, 2, 6.86 gal, 7 gallons
How to use
Enter how many rooms you are painting and their average dimensions. The calculator totals the wall area across rooms, applies coats and waste, and tells you how many gallons to buy.
FAQ
How do I calculate how much paint I need for a room?
Add the length and width, multiply by 2 for the perimeter, then multiply by wall height for gross wall area. Subtract doors (21 sq ft each) and windows (15 sq ft each), then divide by your paint's coverage per gallon and multiply by coats.
Do I need primer before painting?
Primer is recommended on new drywall, bare wood, stained or glossy surfaces, and for dramatic color changes. On previously painted smooth walls, two top coats usually work without primer.
How many coats of paint do I need?
Two coats are standard for even coverage. Dark-to-light or light-to-dark color changes often need a third coat or a quality primer first.
What is the difference between latex and oil-based paint?
Latex (water-based) dries fast, cleans up with soap and water, and is the standard for walls and ceilings. Oil-based (alkyd) is tougher and better for trim, but needs mineral spirits to clean up and has stronger fumes.
Why should I buy extra paint?
Buying about 10% extra covers touch-ups, mistakes, and coverage variations between brands. Running out mid-project means color-matching problems.