Paint Calculator
Enter your room dimensions or total square footage to find exactly how many gallons of paint you need.
Calculation method
Each subtracts ~20 sq ft
Each subtracts ~15 sq ft
Paintable surface area
Results
Gallons
—
gallons needed
Quarts
—
if buying quarts
Sq Ft to Paint
—
sq ft (all coats)
How to Calculate Paint Coverage
Standard interior paint covers approximately 350 square feet per gallon on smooth surfaces. For a room, calculate total wall area (perimeter × height), subtract doors and windows, then multiply by coats.
Coverage by Paint Type
| Paint Type | Coverage per Gallon |
|---|---|
| Interior flat / matte | 350–400 sq ft |
| Interior eggshell / satin | 350–400 sq ft |
| Interior semi-gloss | 300–350 sq ft |
| Exterior paint | 250–350 sq ft |
| Primer | 200–300 sq ft |
Frequently Asked Questions
- How many coats of paint do I need?
- Two coats is standard for most interior projects. Going from dark to light or painting new drywall typically requires a primer coat plus two finish coats.
- Should I buy extra paint?
- Yes — buy at least 10% more than calculated and keep a small amount sealed for future touch-ups. Paint batches vary slightly in color, so matching later can be difficult.
- Is it better to buy gallons or quarts?
- Gallons are significantly cheaper per square foot. Only buy quarts if you need less than half a gallon or for small accent areas.