Paint coverage varies enough by surface and color change that eyeballing gallons either leaves you short mid-job or sitting on unopened cans. This calculator works from room dimensions, deducts doors and windows, applies your coverage rate and coat count, and rolls in a labor cost so you can quote a paint job from measurements alone.
Master 16×14×9, Bed 2 12×11×9, Bed 3 12×10×9. Each with 1 door, 2 windows, 2 coats. Paint $42/gal, labor $1.50/sq ft.
20×18×10 ft room with ceilings, 2 doors, 3 windows, 2 coats.
5 offices averaging 14×12×9, 1 door + 1 window each, 1 coat, labor $1.25/sq ft.
Most interior paints cover 350–400 sq ft per gallon on smooth surfaces with one coat. Rough or porous surfaces (bare drywall, masonry, heavy texture) absorb more and may only get 200–300 sq ft per gallon. Premium paints and primers have higher coverage rates. Use 350 sq ft/gal as a safe default for interior latex.
Two coats are standard for most repaint jobs. Going from dark to light (or light to dark), painting a new color over a different color, or painting new drywall requires 2–3 coats. Painting the same color for touch-up may only need 1 coat. Always include a primer coat when painting bare surfaces — enter it as a separate room if needed.
Yes, for an accurate estimate. Standard doors are ~20 sq ft, standard windows are ~15 sq ft. Subtracting these from wall area gives a more precise gallon count and avoids over-ordering on larger rooms with many openings. This calculator handles the deduction automatically.
Ceilings are often a separate color (flat white) and require separate pricing. Toggle the "include ceilings" option on when the ceiling is the same color or you're quoting a full room package. Turn it off when quoting walls-only work.
Professional interior painting typically runs $2–$6 per sq ft of paintable surface, depending on prep work, number of coats, trim detail, and region. Labor accounts for 70–80% of most paint jobs. Use this calculator to price by room and build a full labor + material estimate.