How much paint is needed for a 12×12 room?

The world economy has suffered a remarkable downtrend amid prolonged uncertainties. This downtrend has impacted most people around the globe, and so it’s important to determine how much paint you need for a specific room in order to avoid wastage. It’s often a tricky calculation with multiple variations extending from your painting approach to the composition and state of your walls. Buying too much paint will result in wastage and storage problems. On the other hand, buying too little means that you will be delayed and that you’ll have to make another trip to the store. None of the outcomes are favorable, but fortunately, with proper planning, you are very well covered.

Painting The Walls

In order to paint the walls, first of all, you’ll need to determine the surface area of the walls by multiplying the perimeter around the room by the height of the ceiling. For a 12 by 12 room, you’ll take the perimeter, which is (12 ft. + 12 ft.) x 2, and multiply by the ceiling height, 12 feet. The total is 576 square feet. The total surface area of the walls is determined by subtracting the area for doors and windows from the total wall area. Hence, the total wall surface to be painted is 540 square feet. As a standard guideline, in dry and wet conditions, one gallon of paint will most often paint 400 square feet. For this reason, the walls, which cover 540 square feet will require 1.35 gallons of paint and will be sufficient to cover one coat of paint. Coverage of the paint in many cases will be influenced by the texture and porosity of the walls. It’s recommended that two coats be used for bright colors.

Painting the Ceiling

By employing the rule of thumb, you determine the amount of paint required for the ceiling by multiplying the width by the length of the room. The surface area of the ceiling for paint coverage will be 144 square feet. Again, given that one gallon of paint covers 400 square feet, 144 square feet will require 0.36 gallons of quality paint. To avoid surface imperfections, a flat finish is preferred.

Paint doors and windows

To determine the amount of paint you need for the doors and windows, you should, first of all, calculate their surface area. Also, often calculate while factoring two paint coats as that will guarantee that you do a decent work. For a 12 x 12 room, the surface area of the door and window is estimated to be 21 and 15 square feet respectively. Therefore, two coats of paint for the door and window will be approximately 72 square feet. Subsequently, they will require 0.18 gallons of quality paint.

Total Amount of Paint Required

The total amount of paint needed for a 12 x 12 room is thus the sum of the amount of paint required for painting the walls, the ceiling, the window, and the door, which is 1.89 gallons of paint. What’s more, various factors also play a part in determining the paint coverage, like the types of paint, wet and dry conditions, and also the painting technique used.


In general, it’s always advisable to round up and buy more paint than the calculations show you’ll need. The extra paint may be of use in future reworks. If you find it challenging to do the math, find a professional in the field who will guide you accordingly. More so, call us now at 831-269-2837 if you need any paint job assistance.