How to Calculate Paint Quantity

Painting Ceilings

Calculate ceiling paint separately: Room length × Room width = Sq ft. Divide by 350.

Example: 12 ft × 10 ft = 120 sq ft ÷ 350 = 0.34 gallons (buy 1 gallon)

Dramatic Color Changes

Going from dark to light? Add 50% more paint. You'll likely need 3 coats instead of 2.

Deep Colors

Rich reds, deep blues, or dark grays often require 3 coats for true color. Add 50% to your paint estimate.

Textured Walls

Popcorn ceilings, heavily textured walls, or rough surfaces use 20-30% more paint. Use 300 sq ft per gallon instead of 350.

How much area does one gallon of paint cover?

One gallon of paint covers approximately 350-400 square feet per coat on smooth walls. Textured walls, rough surfaces, or porous materials may reduce coverage to 250-350 sq ft per gallon. Always check the paint can for manufacturer's specific coverage rate.

Do I need to subtract windows and doors when calculating paint?

Yes, subtract large openings from your square footage. A standard door is about 21 sq ft (3 ft x 7 ft), and a standard window is about 15 sq ft (3 ft x 5 ft). However, for smaller windows or if you have just a few, some painters skip this step and use the extra paint for touch-ups.

How many coats of paint do I need?

Plan for 2 coats as standard. You may need 3 coats when painting very dark colors, covering dramatic color changes (dark to light), or painting over red or orange tones. One coat rarely provides adequate coverage or durability.