Estimate drywall sheets, joint compound, tape, screws and corner bead from your wall and ceiling area, with a waste factor and a regional material-cost estimate. Compare 4x8 and 4x12 sheets side by side.
sheets = (wall + ceiling − openings) ÷ sheet area × (1 + waste)
4×8 = 32 ft² · 4×12 = 48 ft²
A 4×8 sheet covers 32 ft²; a 4×12 covers 48 ft² and gives cleaner ceiling joints with fewer butt seams to hide. Switch the sheet-size tab to compare the count and material cost both ways — larger sheets usually cut your total, but need a drywall lift and a clear path through doorways.
Use 10% waste for simple rectangular rooms and 15% where there are many openings or corners. Plan about 0.05 lb of joint compound per square foot per coat (roughly 0.15 lb/ft² over a three-coat Level 4 finish), about one linear foot of tape per square foot of board, and screws weighted toward the ceiling, where 12-inch spacing uses more than the 16-inch spacing on walls.
Walls: perimeter is 2 x (14 + 16) = 60 ft, times 9 ft high = 540 square feet of wall. Ceiling: 14 x 16 = 224 square feet. Subtract a door (about 21 sq ft) and two windows (about 30 sq ft) for 51 square feet of openings. Net surface: 540 + 224 − 51 = 713 square feet.
Using 4 x 8 sheets (32 sq ft each): 713 ÷ 32 = 22.3 sheets, and at 10% waste that's about 25 sheets. Switch to 4 x 12 sheets (48 sq ft) and the same room takes about 17 sheets with fewer butt joints to finish. For consumables, plan roughly 0.05 lb of joint compound per square foot per coat — about 113 lb over three coats, or two 4.5-gallon buckets — plus about 780 linear feet of tape (4 rolls), and screws weighted for tighter ceiling spacing (around 860). At national-average prices that's roughly $470 in materials before tax; in a high-cost metro like New York it runs closer to $670.
Cutouts at doors, windows, and outlets generally can't be reused, so the opening area does not reduce your sheet count by its full amount — the waste factor covers this.
About 17 sheets of 4×8 including 10% waste, for roughly 478 ft² of wall and ceiling. The same room takes about 12 sheets of 4×12.
Plan about 0.15 lb of compound per square foot of board over a three-coat finish — roughly one 4.5-gallon bucket per 400 ft² — and about one linear foot of tape per square foot, so a 250-foot roll covers around 250 ft² of board.
About 32 per 4×8 sheet on walls at 16-inch spacing, and closer to 40 on ceilings, where 12-inch spacing prevents sag. The calculator weights ceiling area at the higher rate automatically.
Subtract large openings only. The offcuts around small windows, outlets and switches usually can't be reused, so deducting them under-estimates — the waste factor is there to cover it.