How-To Guides · DIY & home

How Much Paint Do I Need? (Easy Room Math)

Standing in the paint aisle, wondering how many gallons to grab? You only need a tape measure and some easy math. Let's figure out a real room together.

1. Step 1: Measure The Walls

Step 1: Measure The Walls

Measure the length of each wall, and add them up. Our room is twelve by fourteen feet, so that's twelve, plus fourteen, plus twelve, plus fourteen. Fifty two feet all the way around.

2. Step 2: Times The Height

Step 2: Times The Height

Now multiply by the wall height. Our walls are eight feet tall. Fifty two times eight is four hundred sixteen square feet of wall.

3. Step 3: Subtract Doors And Windows

Step 3: Subtract Doors And Windows

You won't paint the doors and windows, so take them out. A simple rule is about twenty square feet for each door, and fifteen for each window. We have one door and two windows. That's fifty square feet, which leaves three hundred sixty six.

4. Step 4: Two Coats

Step 4: Two Coats

Most walls need two coats, especially if you're changing colors. So double it. Seven hundred thirty two square feet.

5. Step 5: Divide By Coverage

Step 5: Divide By Coverage

Check the label on the can. One gallon usually covers about three hundred fifty to four hundred square feet. To be safe, use the low number. Seven thirty two divided by three fifty is about two point one gallons.

6. What To Buy

What To Buy

So grab two gallons and one quart. If your walls are rough, or the color change is big, pick up a little extra. Leftover paint is handy for touch ups.

Tools that make this easier

Simple Google Sheets + Excel tools from WiscHaven. Buy once, no subscription.

Sources

Checked against the official sources above. Steps can change as apps update - tell us if something looks different: wischavenindustries@gmail.com