Paint gallons guide
How Many Gallons of Paint Do I Need for One Room?
Most average bedrooms need 1 to 2 gallons of wall paint, but the right number depends on room size, wall height, number of coats, paint coverage, doors, windows, ceiling, and waste.
For one average room with 8-foot walls, plan around 1 gallon for one coat or 2 gallons for two coats. Add more if the room is large, has tall walls, includes the ceiling, has textured walls, or needs primer.
Use the paint calculatorPaint gallons formula for one room
Use this formula to estimate paint before you shop:
| Step | Formula | Example |
|---|---|---|
| Wall area | (Length + width) x 2 x wall height | (12 + 10) x 2 x 8 = 352 sq ft |
| Subtract openings | Subtract doors and windows | 352 - 20 - 30 = 302 sq ft |
| Adjust for coats | Paintable area x coats | 302 x 2 = 604 sq ft |
| Add waste | Add 10% for touch-ups and measuring error | 604 x 1.10 = 664 sq ft |
| Convert to gallons | Adjusted area / coverage per gallon | 664 / 350 = 1.9 gallons |
Common room examples
The table below assumes 8-foot walls, one door, two windows, two coats, 10% waste, and 350 square feet of coverage per gallon.
| Room size | Approximate paintable wall area | Paint to buy |
|---|---|---|
| 10x10 room | 270 sq ft | About 1.75 gallons |
| 10x12 room | 302 sq ft | About 2 gallons |
| 12x12 room | 334 sq ft | About 2.25 gallons |
| 12x15 room | 382 sq ft | About 2.5 gallons |
| 15x15 room | 430 sq ft | About 2.75 gallons |
Should you round paint gallons up?
Yes. Paint is usually sold by quart, gallon, or five-gallon bucket. Round up enough to finish the project and save a small amount for touch-ups. If the estimate is 1.9 gallons, buying 2 gallons is usually practical. If the estimate is 2.1 gallons, compare the cost of adding a quart versus buying another gallon.
How ceiling paint changes the estimate
A ceiling adds length x width square footage before coats and waste. A 12x12 ceiling adds 144 square feet. If you are painting one ceiling coat with the same coverage assumption, that can add about half a gallon before rounding.
When one gallon is enough
One gallon can be enough for a small room, a single accent wall, a powder room, a closet, or one coat over a similar color. It is less likely to be enough for two full coats in a standard bedroom.
When you need primer
Primer is separate from finish paint. Add primer when painting new drywall, covering stains, changing from dark to light, painting patched walls, or painting glossy surfaces. In the CoatWise calculator, turn on primer to estimate primer gallons separately from paint gallons.
Estimate your room more accurately
Measure room length, width, wall height, doors, and windows. Then use the interior painting cost calculator to adjust coats, coverage per gallon, waste, ceiling, primer, paint price, supplies, and labor.
Planning note
Paint labels commonly give coverage in square feet per gallon, but the final amount depends on surface texture, application method, color change, and product quality. Check the label on the paint you plan to buy before purchasing.