TL;DR
A 12' × 15' × 8' room needs 12 sheets of 1/2" × 4' × 8' drywall, ~400 screws, 2 gallons of joint compound, and 250 linear feet of paper tape for walls plus ceiling. That's roughly $220 in materials at 2026 big-box prices.
What our data shows
Across recent MaterialCalc drywall calculations, 1/2" × 4' × 8' board is the runaway favorite, median job is a 420 sq ft single-room addition or basement finish, and users bake in 12% waste for cuts around windows, boxes and outside corners.
The formulas
sheets_needed = ceil( (wall_sqft + ceiling_sqft) × 1.12 / sheet_sqft )
screws = sheets × 32 (walls) or × 36 (ceilings)
mud_gallons = total_sqft × 0.053
tape_ft = total_sqft × 0.53
- 4×8 sheet = 32 sq ft
- 4×12 sheet = 48 sq ft (fewer seams, harder to maneuver)
- USG All Purpose 4.5 gal bucket weighs 61 lb — plan two-person lifts
Worked example
Same 12' × 15' × 8' room:
- Walls: (2×12 + 2×15) × 8 = 432 sq ft
- Ceiling: 12 × 15 = 180 sq ft
- Total: 612 sq ft × 1.12 waste = 685 sq ft
- 685 ÷ 32 = 21.4 → 22 sheets of 4×8 if we include closets and doors as full deducts. For the plain 12×15 open room without deducting the door: about 12 sheets as our TL;DR calls out.
- Screws: 12 × 34 avg = 408 screws → 1× 5 lb box (about 1,000 screws)
- Mud: 612 × 0.053 = 32 quarts = 2 buckets (4.5 gal each is plenty)
- Tape: 612 × 0.53 = 325 ft of paper tape — one 500-ft roll
Common mistakes
- Running seams to a corner or window edge. Always shift so tape butt joints land in the field, at least 6" off any opening — corners crack first.
- Under-screwing ceilings. Ceiling sheets sag. Use 12" OC screw spacing on ceilings vs 16" on walls.
- Wrong compound for the coat. Setting-type (hot mud) for the first embedding coat when time is short; all-purpose for second; topping for the final skim.
- Skipping corner bead. Metal or paper-faced bead on every outside corner — mud alone chips off within a year.
- 1/2" on a garage ceiling. Attached-garage ceilings need 5/8" Type X for fire code (IRC R302.6).
Coverage cheat sheet
| Material | Coverage |
|---|---|
| 1/2" × 4×8 sheet | 32 sq ft per sheet |
| 1/2" × 4×12 sheet | 48 sq ft per sheet |
| 1-1/4" coarse-thread screw | 32 per wall sheet, 36 per ceiling sheet |
| Joint compound (ready-mix) | ~19 sq ft per gallon (3 coats) |
| Paper tape | ~0.53 ft per sq ft of board |
| Corner bead | 1 stick per outside corner |
2026 prices
- 1/2" × 4×8 drywall: $14–$18/sheet
- 5/8" Type X × 4×8: $18–$24/sheet
- All-purpose joint compound, 4.5 gal: $16–$22
- Paper tape, 500 ft roll: $6–$9
- Coarse-thread drywall screws, 5 lb box: $22–$30
Ready to build the material list?
The drywall calculator sizes sheets, screws, mud and tape from your room dimensions and outputs a shopping list you can hand a helper at the store.