Drywall Calculator
How many sheets to rock a 12×12 room? Enter the dimensions, knock out the doors and windows, and get the sheet count plus the mud, tape, and screws to finish them — handy for comparing against a drywaller's materials line.
−21 sq ft each
−15 sq ft each
Sheet size
Sheets
17
4×8, incl. 10% waste
Board area
492
sq ft (348 walls + 144 ceiling)
Openings deducted
−36
sq ft
Joint compound
26 lb
1 × 4.5-gal bucket
Joint tape
185 ft
1 × 250-ft roll
Screws
544
3 × 1-lb box (~200)
Estimates: 10% cutting waste, 21 sq ft deducted per door and 15 per window, ~32 screws per sheet on 16" OC framing, and joint compound at one 61.7-lb (4.5-gal) bucket per ~1,000 sq ft of board — taping coats only; texture or skim coats need considerably more.
How Drywall Math Works
Wall area is the room perimeter times ceiling height: a 12×12 room with 8-ft ceilings has 2 × (12 + 12) × 8 = 384 sq ft of wall. The estimate deducts 21 sq ft per door and 15 per window (384 − 36 = 348), adds the 144 sq ft ceiling for 492 sq ft of board, then pads 10% for cuts before dividing by sheet area — 492 × 1.10 ÷ 32 = 16.9, so 17 4×8 sheets. Finishing supplies are estimated at 0.053 lb of joint compound per square foot of board (one 61.7-lb, 4.5-gal bucket per roughly 1,000 sq ft — taping coats only, texture and skim coats need more), 12 ft of tape per 32 sq ft of board, and about 32 screws per sheet on 16" on-center framing.
Worked example — 12 × 12 ft room, 8-ft ceiling
Walls = 2 × (12 + 12) × 8 = 384 sq ft Openings = 1 door (21) + 1 window (15) = −36 Ceiling = 12 × 12 = +144 Total = 492 sq ft Sheets = ceil(492 × 1.10 ÷ 32) = 17 (4×8) Compound ≈ 492 × 0.053 lb ≈ 26 lb (1 bucket) Tape = ceil(492 ÷ 32 × 12) = 185 ft (1 roll) Screws = 17 × 32 = 544 (3 boxes)
Frequently Asked Questions
How many sheets of drywall do I need for a 12×12 room?
With 8-ft ceilings the walls are 2 × (12 + 12) × 8 = 384 sq ft; subtract about 21 sq ft per door and 15 per window (down to 348 with one of each), then add the 144 sq ft ceiling for 492 sq ft of board. With 10% cutting waste that's 492 × 1.10 ÷ 32 = 16.9, so 17 4×8 sheets.
Should I use 4×8 or 4×12 sheets of drywall?
Bigger sheets mean fewer joints to tape: hung horizontally, a 4×12 spans a 12-ft wall with a single seam. The tradeoff is weight and handling — half-inch drywall runs about 1.6 lb per sq ft, so a 4×8 is roughly 51 lb while a 4×12 is 77 lb. Use 4×8 when working alone or up stairwells, and 4×12 with a helper on long open walls.
How much joint compound do I need per sheet of drywall?
Budget about 0.053 lb of compound per square foot of board for the taping coats — one 61.7-lb (4.5-gal) bucket per roughly 1,000 sq ft, or about 1.7 lb per 4×8 sheet. That covers tape coat plus two finish passes over joints and screws; skim coats or heavy texture can double or triple the figure.
How many screws go into a sheet of drywall?
About 32 per 4×8 sheet on 16"-on-center framing — a screw every 12" in the field and closer along edges works out to roughly one per square foot. A 1-lb box of coarse-thread 1-1/4" screws holds about 200, enough to hang six sheets; use coarse thread for wood studs and fine thread for steel.