Painters
Paint Calculator
Calculate how many gallons of paint you need for any room, accounting for doors, windows, and coats.
Wall area: 486 sq ft gross − 70 sq ft (doors/windows) = 416 sq ft net. 2 coats at 350 sq ft/gallon = 3 gallons for walls, 2 gallons for ceiling. Round up to whole gallons when buying.
How much paint do I need for a room?
The standard rule is one gallon of paint covers about 350 to 400 square feet with one coat. For a typical 12x12 room with 8 foot ceilings, the wall area is about 384 square feet. Subtract for windows and doors and you are looking at roughly 330 square feet of paintable surface. So one gallon gets you one coat. For two coats, which is what most jobs need, figure two gallons.
How to calculate wall area for painting
Add up the length of all the walls and multiply by the ceiling height. That gives you the total wall area. Then subtract about 20 square feet for each standard door and 15 square feet for each window. What is left is your paintable area. This calculator does all of that math for you and accounts for multiple coats.
Interior paint coverage tips
Dark colors over light walls might need three coats instead of two. Going from a dark color to a light color usually needs a coat of primer first plus two coats of paint. Textured walls use more paint because the bumps add surface area. Flat paint covers slightly better than satin or semi gloss. Always buy a little extra for touch ups later.
Primer and when you need it
You need primer when you are painting over new drywall, going from dark to light colors, covering stains or water marks, or painting over bare wood. A good primer blocks stains from bleeding through, helps the paint stick, and gives you better coverage with fewer coats. For most repaint jobs where you are going with a similar or darker color, a paint and primer combo works fine.
Common Questions
How long does it take to paint a room?
A single bedroom takes most people 3 to 5 hours including prep, two coats, and cleanup. A bigger room or one with lots of trim can take a full day.
Flat vs satin vs semi gloss paint which should I use?
Flat hides wall imperfections but scuffs easy. Satin is the workhorse for living rooms and bedrooms. Semi gloss is best for kitchens, bathrooms, and trim because you can wipe it clean.
Can I paint over wallpaper?
You can, but it is not ideal. The seams and texture usually show through. If you do it, prime with an oil based primer first to keep the wallpaper glue from bubbling. Removing the wallpaper first gives a much better result.
How long should I wait between coats of paint?
Wait 2 to 4 hours between coats for latex paint. Oil based paint needs 24 hours. If the first coat is tacky to the touch, it is not ready for the second coat yet.
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