Paint Quantity Calculator
Calculates gallons of paint needed based on wall area, number of coats, and coverage rate
Length of the room in feet
Width of the room in feet
Height of the walls in feet
Each door subtracts 20 sq ft from paintable area
Each window subtracts 15 sq ft from paintable area
Number of paint coats to apply
Total area of all walls combined
Wall area minus doors and windows
Based on 350 sq ft coverage per gallon
Frequently Asked Questions
How much area does a gallon of paint cover?
One gallon of interior paint covers approximately 350-400 square feet on smooth surfaces. Rough or textured walls absorb more paint and reduce coverage to around 250-300 square feet per gallon. Always check the label for the specific product.
Do I need one coat or two coats of paint?
Two coats are recommended for most projects, especially when changing colors or painting over a darker shade. One coat may be sufficient with high-quality paint-and-primer-in-one products when painting a similar color over a well-prepared surface.
How do I account for doors and windows when calculating paint?
Subtract about 20 square feet per standard door and 15 square feet per average window from your total wall area. This prevents you from overbuying, though a small surplus is always good to have for touch-ups.
How much paint do I need for a ceiling?
Calculate ceiling area separately (length times width of the room). Ceiling paint is thicker and covers about 350 square feet per gallon. Most ceilings need only one coat unless you are covering a dark color or stains.
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