How much paint do I need? It can be a tricky question.
You only want to have to buy paint once, but you don’t want to buy too much more than you need. Why waste money on paint you won’t use?
It’s fairly important (for more than convenience’s sake) to purchase all of the paint you will need at once. Colors will vary slightly from one batch to the next. Even with today’s color-matching paint technology, sometimes there is a slight tone difference between batches.
With this in mind, calculating the amount of paint you need is actually fairly simple.
Most paint manufacturers claim that one gallon of paint will cover 400 square feet of surface. But this is only an estimated figure, and a fairly generous one at that.
A gallon may cover 400 square feet under perfect conditions, and then only if you need a single coat. Fairly new drywall or plaster may soak up a fair amount of paint, especially if there are areas that have not been well primed.
You are far safer to begin your estimation with the understanding that a gallon of paint will cover approximately 300 square feet of surface, per coat.
Note: If you plan on more than one coat (and you should, unless you are painting a decorative finish on top of a base coat), double the amount of square footage you need to cover. Example: You have 600 square feet of surface to paint, times 2 coats = 1200 Sq. feet, or 4 gallons of paint.
This works out well, because you will likely have some leftover paint available for the inevitable future touch ups.
Calculating Your Square Footage
One common mistake people make when calculating square footage for paint is to take the width and length of the room, and multiplying them for square footage. This will give you the square footage of the room but not of the walls.
Works for flooring, but not for paint.
To calculate the square footage of walls, you must do each wall separately and add that square footage together.
First, take the length of each wall, and multiply it by the height. Example, a wall is 12’ long by 8’ high. The square footage of that wall is 96’.
Do this for each wall you plan to paint. When you have the square footage of each wall, add those together to get an approximate idea how many gallons of paint you will need (remember 300 square feet per gallon).
As a final example, I will give you a rectangular room that is 14x12x8. That is, the two longer walls are 14’ in length, the shorter are 12’, and the walls are 8’ high. Hence, you take 14x8=112. The two longer walls each have an area of 112 square feet. The shorter walls (12x8=96) each have an area of 96 square feet.
Now, add them together. 112+112+96+96=416 square feet.
Two coats? No problem, simply double the square footage…832 square feet. Or about 3 gallons of paint.
Fairly simple, right?