Planning an interior room
Most interior projects start with wall area: the same measurement drives paint, wallpaper, and drywall. From there, add the finishing details — baseboard and crown molding run along the room's perimeter, while a drop ceiling is figured by tile and grid. If you're opening up walls, it's also the right time to size insulation and check the room's heating and cooling load.
Which calculator do I need?
- Paint and wallpaper — wall coverings, from wall area, coats, and openings.
- Drywall and joint compound — sheets, screws, and the mud to tape and finish them.
- Baseboard and crown molding — trim along the room's perimeter.
- Drop ceiling and countertop — suspended-ceiling tiles and grid, or counter material.
- Insulation and BTU — comfort: R-value coverage and heating/cooling load.
One measurement drives most of it
The handy thing about interior work is that a single number — your wall area (perimeter × height) — feeds paint, wallpaper, and drywall at once, while the perimeter alone sizes baseboard and crown. Measure once and you can plan the whole room. Don't forget the supporting materials: drywall needs joint compound and tape, paint often needs primer, and trim has its own caulk and fasteners. Buy from one batch and keep a little extra for touch-ups and repairs.