Paint Calculator
Calculate how many gallons of paint you need for walls and rooms. Enter dimensions to estimate coverage with adjustments for doors, windows, and multiple coats.
Recommended Tools & Supplies
FrogTape ProGrade Blue Painters Tape, 1.5 Inch, 6 Rolls
Professional painter's tape with PaintBlock technology for crisp, clean lines.
View on Amazon
INCLY Full Face Dust Mask - Reusable Respirator
Safety mask for protection against dust, paint, chemical fumes, and vapors.
View on AmazonAs an Amazon Associate, I earn from qualifying purchases. This helps keep our calculators free!
How to Use This Calculator
Calculate exactly how much paint you need to avoid multiple store trips or wasteful over-buying:
- Measure the height and width of each wall you plan to paint.
- Enter the room dimensions or total wall area in square feet.
- Subtract areas for windows and doors (or use our default estimates).
- Select whether you need one or two coats (two is recommended for most color changes).
- Click 'Calculate' to see gallons needed based on standard coverage of 350-400 sq ft per gallon.
Why This Matters
Paint is sold by the gallon, and getting the quantity wrong is frustrating either way. Too little means a mid-project trip to the store and potential color matching issues with different batches. Too much means wasted money on paint that will eventually dry out. Proper calculation also helps you budget accurately - quality paint runs $30-70 per gallon, so errors add up quickly on larger projects.
- Avoid mid-project store runs and color batch variations
- Save money by not over-buying paint that will go to waste
- Budget accurately before starting your painting project
- Account for multiple coats needed for dramatic color changes
- Plan primer needs separately from finish coat requirements
Worked Examples
Standard Bedroom
12' x 14' room with 8' ceilings, one door, two windows. Two coats of new color.
Living Room
18' x 20' great room with 10' ceilings, multiple windows. One coat refresh.
Accent Wall
Single 14' wide × 9' tall accent wall, dark color over light.
Common Mistakes to Avoid
- Forgetting that two coats are usually needed - especially for color changes or covering dark colors.
- Not accounting for textured walls - they can require 20-30% more paint than smooth surfaces.
- Using ceiling paint coverage rates for walls - ceiling paint is thinner and covers more area.
- Forgetting primer when needed - dramatic color changes or new drywall need separate primer.
- Not keeping some extra paint for touch-ups - buy a quart extra for future repairs.