Bag & BucketPaint Calculator: How Many Gallons?
Enter the floor size of the room and its wall height. The calculator works out the wall area, takes off doors and windows, multiplies by the number of coats and tells you how many gallons and quarts to buy.
Frequently asked questions
How much does a gallon of paint cover?
Most interior paints cover 250–400 square feet per gallon per coat. We use 350, a middle figure for smooth, previously painted walls.
Do I need two coats?
Usually yes: two coats give even color and hide the old paint. One coat can be enough for the same color over a clean wall.
Should I use primer?
Prime new drywall, bare wood, stains, or a big color change (dark to light). Primer covers about the same area per gallon as paint.
Developers: GET /api/paint-calculator returns JSON.