Interior Finishes calculators
Drywall, paint, tile, flooring and trim — the indoor jobs.
- Drywall CalculatorSheets, screws, mud and tape for any room
- Paint CalculatorGallons for walls, ceilings and trim
- Tile CalculatorTiles and boxes, plus adhesive and grout
- Backsplash CalculatorTile, sheets, mastic, grout and edge trim
- Shower Tile CalculatorTile, backer board, membrane, thinset and grout
- Flooring CalculatorBoxes, underlayment and cost
- Baseboard CalculatorLengths to buy, with corners counted
- Crown Molding CalculatorLengths to buy, plus the saw settings
- Wallpaper CalculatorRolls, allowing for pattern repeat
- Carpet CalculatorSquare yards, and whether it seams
- Shiplap CalculatorBoards of shiplap or panelling
What is in this category
Everything that goes on the inside faces of a room: the board on the walls, the paint or paper over it, the floor underneath, and the trim that covers the joints where those three meet. Ten calculators, covering the jobs that make up most home renovations.
They divide into three groups by what you are actually measuring:
- Wall area — perimeter times ceiling height. That is what drywall, paint and wallpaper need.
- Floor area — length times width. That is what flooring, tile and carpet need.
- Perimeter — the distance around the edge, in linear feet. That is what baseboard and crown molding need.
Three completely different numbers from the same room, which is why it pays to write all three down while the tape measure is still in your hand. Our guide on measuring a room covers the whole checklist.
The two rooms that do not follow the rules
Kitchens and bathrooms have their own calculators here for good reason. A backsplash is a band measured in linear feet along the counter, not a rectangle — and the wall behind the range is usually taller than the rest. A shower is five surfaces at once, with a curb and a niche and a waterproofing layer that costs as much as the tile.
Running either of those through a general floor tile calculator gets you the wrong number, which is why they are separate.
What catches people out indoors
Openings. A door is a hole in the wall, but cutting around it wastes material, so subtracting the full opening leaves you short. The working rule is to ignore anything under about 20 sq ft, deduct half between 20 and 50, and deduct the whole thing above that.
Texture. A textured wall has more actual surface than its measured area — that is what texture means. Heavy knockdown can cut paint coverage by 30%.
Ceiling height. "Eight foot ceilings" is a habit, not a fact. A lot of houses built since 1990 have nine feet downstairs, and on a 52 ft perimeter that is 52 extra square feet of wall.
Order of work. Paint before the floor goes down, trim after. Getting that backwards is the most common sequencing mistake in a room — our guide on the order of operations walks through the whole sequence and what you can order at each stage.