How to use this calculator
- Measure each wall. Length and ceiling height in feet. Add up the perimeter of all walls in the room, or enter the total square footage if you already have it.
- Include the ceiling. Most rooms have a sheetrocked ceiling — toggle it on if so. Ceiling area = room length × width.
- Subtract openings. Doors and windows can be subtracted, but most pros do not — the cuts produce smaller usable scraps but the dollar savings are small.
- Read your result. The calculator returns 4×8 sheet count, the screw count for studs on 16-in centers, and the gallons of joint compound for taping and finishing.
Formula
Sheets = Total wall ft² ÷ 32 (for 4×8 panels)
Worked example
A 12 ft × 14 ft room with 8 ft ceilings has 416 ft² of wall (52 ft × 8 ft) plus 168 ft² of ceiling = 584 ft². Sheets needed: 584 ÷ 32 = 19 sheets (round up to 20). Screws: ~700. Joint compound: 4–5 gallons.
Tips for accurate results
- Buy 10% more than you think — broken corners and miscuts add up.
- Use ⅝-inch sheetrock on ceilings and where code requires fire-rated assemblies (party walls, garages).
- Screws every 12 inches on ceilings, every 16 inches on walls. For ½ in sheetrock use 1¼ in screws; for ⅝ in use 1⅝ in.
- A 5-gallon bucket of all-purpose mud covers about 200–250 ft² of wall through three coats.