How much paint do I need?


We all know that paint is one of the most inexpensive ways to really change the look of a room. Knowing how much paint to buy is important. Buy too much, and you've spent money you didn't need to spend. Buy too little and you have to make a frantic run to the store for more paint. (Not that I've ever had to do that myself, mind you!)

Now, you can always use an online calculator to figure how much paint you need, but I think everyone should know how to do the math, as well. So in case you didn't know, here is a handy guide.


How to calculate wall area


1. Find the perimeter of the room by adding wall lengthsExample: Our example room is 10x12. 10 + 10 + 12 + 12 = 44 ft. 


2.  Multiply the perimeter by the wall height. A somewhat typical wall height is 8 feet, but measure to be certain. Example: Our example room is pretty standard and has 8 foot ceilings. 44 x 8 = 352 sq. feet


3. Subtract area of doors and windows.  If they're an odd size, you can figure the area by multiplying the height x width. Standard doors you can figure on being 20 sq. ft. and standard windows you can figure on being 15 sq. ft. Example: Our example room has 2 doors and 1 window. 20 x 2 = 40 + 15 = 55 sq. ft. Subract from the wall area- 352 - 55 = 297 sq. ft. 


more paint

So, how much paint do I need?


Most paint manufacturers claim one gallon of paint will cover 400 square feet, but I generally figure on about 300 square feet to one gallon of paint.  If you're not changing colors radically from dark to light or from light to dark and are using a good quality paint, you can probably get by with one coat of paint. If you are changing colors radically or are painting your room red (I've always struggled with red!), plan on a *minimum* of two coats, possibly more. So, with our example room we'd need to buy one can of paint if we're not changing the color radically, or at least 2 if we were changing the color quite a bit. 


Just remember: if you're in doubt, round up, not down!  


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BETTY on Jan 24, 2015:

700 sq,ft apartment.

Living room has 2 door and  1 double window.

Kitchen has 1 door and 1 regular window.

Bathroom 1 tiny window  and 1 door

Bedroom 1 window and 1 door and 1 closet door

2ND Bedroom 1 door 1 window and 1 closet door.

Hallway 1 door

DLinder on Nov 29, 2013:

I'm doing 1 wall of a 9X10 room, no windows. We are doing a  chalkboard paint. So do I then divide the amount by 4 then and only need 76 sq. ft of paint? Please help! If I'm not correct, Please let me know much I really need. Thank you.

Dianna on Apr 04, 2012:

Help!! I'm painting a room that is 13'0" by 12'0" with a  bay window that measures 7'6" by 5'0"  with each window measuring 2'6" by 1'8" and a door that is 3'6" by 6'6" high also a widow that is 5'0" by 3'6" how do i figure how much paint i need


been there on Jul 07, 2011:

Also, newer homes with builder grade paint on drywall will SOAK up alot of the first coat and will need two coats to get a consistent color!

Joey Boy on Jun 22, 2011:

this is awesome.. i'm painting my exterior in a week from now.. what's the good for it.. matte or glossy?

Moony on Jan 17, 2010:

Very useful , I am painting my daughters room for the first time and had no idea about paint needed.

roadvermin on Feb 16, 2007:

Funny, we are about to go through the 'painting' thing soon too. I can't stress how useful simple white paint is to have around (for colour blocking or fixing up) as well as a non matte black for defining.

badbadivy on Feb 16, 2007:

Very good point, Manzabar, and it's something I definitely should have mentioned- primer is great stuff!

Manzabar on Feb 16, 2007:

Also if you're making the transition from dark to light, I'd strongly recommend laying down a coat of primer on the wall before you start in with your paint.

Cantalyssa on Feb 16, 2007:

I can't stress how important the "good quality" paint is.  We made that mistake in the past.

KatNap on Feb 15, 2007:

Your timing is perfect!

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