How to Calculate Paint Quantity for Your Room

Calculating the exact amount of paint you need prevents wastage and multiple trips to the hardware store. Here is the foolproof formula used by professionals:

Step 1: Measure the Perimeter

Add the lengths of all the walls in your room. For example, a 10x12 room has a perimeter of 44 feet.

Step 2: Calculate Wall Area

Multiply the perimeter by the ceiling height. If your ceiling is 10 feet high, 44 x 10 = 440 square feet.

Step 3: Subtract Doors and Windows

Deduct 20 sq. ft. for each door and 15 sq. ft. for each window. If you have 1 door and 2 windows, subtract 50 sq. ft. Your total paintable area is 390 sq. ft.

Step 4: The Paint Rule

Generally, 1 gallon (about 3.78 liters) covers up to 400 sq. ft. for a single coat. Always buy an extra quart for touch-ups!