How Much Paint Do I Need for a Kitchen or Bathroom?

To find out how much paint you need, multiply your room's wall area by the number of coats, subtract about 10% for doors and windows, and divide by the coverage of one gallon. For kitchens and bathrooms, we use 350 square feet per gallon, because moisture- and mildew-resistant paints tend to cover slightly less than the 400 square feet typical of standard interior paint.

The formula, step by step

1. Perimeter = 2 × (room length + room width), in feet.
2. Wall area = perimeter × ceiling height.
3. Paintable area = wall area minus roughly 10% for doors, windows, and other openings.
4. Gallons = paintable area × number of coats ÷ coverage per gallon (350 sq ft).

Example: a 12 × 10 ft kitchen with 9 ft ceilings

The perimeter is 2 × (12 + 10) = 44 feet, and the wall area is 44 × 9 = 396 square feet. Subtracting 10% leaves about 356 square feet to paint. Two coats means 712 square feet of coverage, and 712 ÷ 350 is just over 2 gallons. The calculator rounds up to the nearest half gallon, so it recommends 2.5 gallons. At $35–$65 per gallon, that is roughly $88–$163.

With a single coat, the same room would need about 1.5 gallons.

Why 350 square feet per gallon?

Many manufacturers list coverage in the range of 350–400 square feet per gallon, and actual coverage depends on the product, the surface, and how you apply it. Rough or porous surfaces, dark colors over light ones, and rolling on thick or thin coats all change the number. We use 350 for kitchens and bathrooms as a slightly conservative figure, so you are less likely to run short. Check the label on the specific paint you choose and adjust.

How many coats?

Two coats is standard for durability in kitchens and bathrooms, which see steam, splashes, and frequent cleaning, especially when you are painting over a different color. One coat may be enough when repainting the same color over a sound, clean surface. If you are going from a dark color to a light one, or painting over bare or repaired drywall, a coat of primer first will improve coverage and finish.

Choosing paint for kitchens and bathrooms

• Moisture and mildew resistance. Look for paints made for kitchens and baths, and combine them with good ventilation. A working exhaust fan makes a bigger difference to mildew than the paint alone.
• Sheen. Satin and semi-gloss finishes hold up better to scrubbing and moisture than flat paint. Satin is a popular choice for walls; semi-gloss is common for trim.
• Price. Mildew-resistant paints commonly run about $35–$85 per gallon. Our calculator's $35–$65 range covers most mainstream products.

What this doesn't include

The calculation covers walls only. Ceilings, trim, doors, cabinets, and primer are separate. To add a ceiling, multiply its length by its width, then divide by the paint coverage per gallon and add that to the wall total. Also buy a little extra for touch-ups, and keep the leftover can labeled with the color and room.