How much paint do I need for a room?
Paint quantity depends on the wall area you actually plan to paint, the number of coats and the coverage of the product. Measure first, then add a small practical allowance if the project needs it.
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- Wall area matters more than floor area for interior paint.
- Two coats roughly double the paintable coverage required.
- Doors and windows can be subtracted when the calculator supports them.
- Always compare the result with the coverage printed on the actual product.
Measure the paintable surfaces
For a rectangular room, wall area comes from the perimeter multiplied by wall height, then adjusted for openings. Ceilings or accent walls should be handled separately when they are not part of the same paint job.
Coverage varies by paint, surface texture, color change and application method, so use the product label rather than assuming every gallon covers the same area.
Round for the way paint is sold
The geometric result may not match a whole can size. When buying material, round based on the package sizes actually available and keep enough for touch-ups if that matters for the project.
Quick questions.
Should I subtract doors and windows?
Usually yes for a closer estimate, especially when openings make up a meaningful part of the wall area.
Does one coat use half as much as two coats?
In the simple coverage model, yes. Real surfaces can absorb paint differently.
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