Paint calculator
How many gallons for the room — walls, optional ceiling, chosen coat count. Coverage assumptions shown below the result.
| Paintable area | |
|---|---|
| Paint, gallons | |
| Primer, gallons |
Openings subtracted (door 21 sq ft, window 15 sq ft). Buy the next size up if the result lands just over a whole gallon — leftover beats a second store run mid-wall.
FAQ
How much does a gallon of paint cover?
Plan on 350 sq ft per gallon per coat on smooth, previously painted walls. Textured or porous surfaces drop to 250–300.
Do I always need two coats?
Two coats is the safe default. Going light-over-light with premium paint can work in one; any color change or new drywall means two, plus primer for the latter.
When do I need primer?
New drywall, patched areas, stains, glossy surfaces, or drastic color changes (especially covering dark colors). Tinted primer saves a finish coat on big changes.
Hiring it out instead? Painter cost pages by city are coming — the methodology already covers how we build them.