How does the paint calculator work?

It multiplies the wall perimeter by ceiling height, subtracts the area of doors and windows, multiplies by the number of coats, and divides by the manufacturer-rated coverage per gallon.

What coverage should I use?

Most interior latex paints cover 350–400 sqft per gallon on smooth, primed surfaces. Drop to ~250 for unprimed or textured walls.

Yes. Houex rounds up to the nearest quarter gallon, but for large jobs add a 10% buffer for touch-ups and color matching later.

Home intelligence

Paint Calculator

Tell us the room. We'll tell you the gallons. Your numbers stay in the URL — copy the link to share or save it for later.

Frequently asked

FAQ

How does the paint calculator work?: It multiplies the wall perimeter by ceiling height, subtracts the area of doors and windows, multiplies by the number of coats, and divides by the manufacturer-rated coverage per gallon.
What coverage should I use?: Most interior latex paints cover 350–400 sqft per gallon on smooth, primed surfaces. Drop to ~250 for unprimed or textured walls.
Should I buy extra?: Yes. Houex rounds up to the nearest quarter gallon, but for large jobs add a 10% buffer for touch-ups and color matching later.

Rooms you can plan with this tool

Real-room inspiration that uses this tool's outputs.

bathroom

Coastal bathroom — board-and-batten, white tile, brushed brass done right

coastal, traditional

dining

Traditional dining room — chair-rail wainscot, brass chandelier, walnut pedestal

traditional

bathroom

Japandi bathroom — river stone, white oak, matte black done correctly

japandi, minimalist