Walls
Calculators for wall projects: how much paint, primer, drywall, and wallpaper to buy, with doors and windows handled for each material and real package sizes.
- Paint Calculator Gallons of wall, ceiling, and trim paint for one room or a whole house, with primer and cost.
- Drywall Calculator Sheets of drywall for walls and ceilings in 4 × 8, 4 × 10, or 4 × 12, with joint compound, tape, screws, and cost.
- Wallpaper Calculator Rolls of wallpaper for a room or an accent wall, counted by strips with pattern repeat and half-drop match.
Measuring walls once for every project
Every wall calculator here starts from the same three measurements: the room’s length, its width, and the wall height. Measure along the floor from corner to corner, and measure height from the floor to the ceiling, not to the top of the baseboard. Write the numbers down in feet and inches. You’ll reuse them for paint, primer, and any patching or new drywall.
Doors and windows are handled the way each material needs. The paint calculator subtracts 20 square feet for a standard door and 15 for a typical window, and you can change both. The drywall calculator subtracts only doors by default, because the piece cut out of a window opening is usually scrap. You can switch it to subtract windows too, or nothing at all. The wallpaper calculator subtracts neither, since the short pieces around a door or window still come from full-length strips. Only wide openings, such as a sliding door, are left out there. Leave small openings in everywhere, such as outlets and switch plates. They’re too small to matter, and the extra covers cutting in around them.
Which order to do things in
If a wall needs repair, do it before you buy paint. Hang and finish drywall first, let the joint compound dry, sand, then prime. Primer seals fresh compound and bare paper so the finish coats look even. After that, paint the ceiling first, then the walls, then the trim, so drips land on surfaces you haven’t painted yet.
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