Paint Calculator
How much paint do I need?
Estimate how many gallons of paint you need for walls, ceilings, trim, doors, windows, and extra coats.
Calculate your paint
What this calculator includes
This estimate uses room length, width, ceiling height, doors, windows, wall coats, and paint coverage. You can also include ceiling paint, trim, primer, and a small buffer for touch-ups.
Common painting supplies
- Interior wall paint
- Primer, if needed
- Painter’s tape
- Rollers, brushes, and paint trays
- Drop cloths or plastic sheeting
- Spackle, sandpaper, and caulk for prep work
Paint buying note
Paint coverage varies by brand, color, wall texture, surface condition, and application method. When in doubt, buy a little extra for touch-ups.
Paint calculator FAQ
How many square feet does a gallon of paint cover?
Many interior paints cover about 300 to 400 square feet per gallon, but coverage depends on the brand, wall texture, color change, and surface condition.
Do I need two coats of paint?
Two coats are common for most interior painting projects, especially when changing colors or painting over darker walls.
Should I subtract doors and windows?
Yes. This calculator subtracts a basic estimate for doors and windows so you do not overestimate the wall area as much.
Should I buy extra paint?
A small buffer is helpful for touch-ups, roller waste, textured walls, and future repairs.
Does this calculator guarantee the exact amount?
No. This is a practical estimate. Always check your paint label and consider your wall condition, texture, color change, and painting method.