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Drywall Calculator

How to use it

1. Measure the room: length, width and ceiling height in feet.
2. Pick a sheet size — 4×8 is easiest to handle; 4×12 means fewer seams on long walls if you have the help and the access.
3. Say whether the ceiling is included, and how many doors and windows to deduct.
4. You get sheets, screws (count and pounds), compound buckets and tape rolls — hanging and finishing in one list.

How the drywall math works

Walls are perimeter × height: a 12 × 14 ft room with 8 ft ceilings has 52 ft of wall × 8 ft = 416 sq ft of wall. Doors (about 21 sq ft each) and windows (about 15 sq ft) come off, the ceiling (length × width) goes on if you are doing it. Divide the net area by the sheet size — 32 sq ft for a 4×8 — and round up. Pros order one extra sheet per room: the one you mis-cut is the one you needed.

Finishing supplies follow the area. Screws run about 1.25 per sq ft (a 4×8 sheet takes roughly 40 between field and edges). Ready-mix compound covers about 380 sq ft per 4.5 gallon bucket across three coats, and paper tape runs about 28 ft per sheet once seams and corners are counted. None of these forgive under-buying — dried compound and half-taped seams do not wait for a store run.

What each number means at the store

Drywall mistakes that cost money

• Sheet count from floor area. Walls are perimeter × height — a small room with tall ceilings needs far more board than its floor suggests.
• Forgetting the ceiling in the order, then mixing sheet batches mid-job.
• One bucket of compound for a whole room. Three coats over 500+ sq ft drinks two buckets; running out mid-coat leaves ridges.
• No deduction thinking in reverse: ordering for openings you then have to cut out is fine (waste), but deducting a window you planned to board over is not — measure the actual job.

Drywall Calculator — common questions

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