Enter your room size, or the total area, to see how many sheets of drywall to buy, plus joint compound and screws.
Quick answers
A 4 × 8 sheet covers 32 sq ft, a 4 × 10 covers 40 sq ft and a 4 × 12 covers 48 sq ft. Divide your wall and ceiling area by the sheet area, add 10% for cuts, and round up.
Joint compound: about 10 gallons per 1,000 sq ft of drywall (USG Sheetrock All Purpose).
Screws go every 16 in on walls and 12 in on ceilings over wood framing (USG), roughly 28 to 36 screws per 4 × 8 sheet.
How to use the drywall calculator
Measure each room's length, width and wall height, or enter the wall and ceiling area directly.
Pick the sheet size you plan to hang. Longer sheets mean fewer joints but are heavier.
Keep at least 10% extra for cuts and mistakes. Use 15% for rooms with many corners or angled walls.
The formula
Sheets = (wall area + ceiling area) × (1 + extra%) ÷ sheet area, rounded up. Wall area is 2 × (length + width) × height and ceiling area is length × width.
Joint compound uses USG's figure of about 10 gallons per 1,000 sq ft. Screws assume framing 16 in on center, with a screw every 16 in along each stud on walls and every 12 in on ceilings, per USG's fastening guidance.
Worked example: a 12 × 12 ft room with 8 ft walls and ceiling
Walls 2 × (12 + 12) × 8 = 384 sq ft, ceiling 144 sq ft, total 528 sq ft. With 10% extra: 580.8 sq ft ÷ 32 = 18.2, so buy 19 sheets of 4 × 8. Joint compound: about 5.3 gallons.
Sheets for common rooms
8 ft walls plus ceiling, 10% extra.
Room
Total area
4 × 8 sheets
4 × 12 sheets
10 × 10 ft room
420 sq ft
15
10
12 × 12 ft room
528 sq ft
19
13
12 × 16 ft room
640 sq ft
22
15
20 × 20 ft garage
1040 sq ft
36
24
Common questions
How many sheets of drywall do I need for a 12 × 12 room?
With 8 ft walls the room has 384 sq ft of wall and 144 sq ft of ceiling, 528 sq ft in total. With 10% extra that is 581 sq ft, or 19 sheets of 4 × 8 or 13 sheets of 4 × 12. Do not subtract small windows and doors; the offcuts are rarely usable.
Should I use 4 × 8 or 4 × 12 sheets?
Longer sheets mean fewer seams to tape and finish, so 4 × 12 sheets usually give a better wall with less mud. They are heavy: USG lists its lightweight 1/2 in panels at 1.2 to 1.3 lb per sq ft, so even a lightweight 4 × 12 sheet is about 58 to 62 lb. A 4 × 8 is easier for one person or a ceiling without a lift.
How much drywall mud do I need?
USG puts all-purpose joint compound at about 10 gallons per 1,000 sq ft of panels. A 12 × 12 room with ceiling (528 sq ft) needs roughly 5.3 gallons, so one 4.5 gallon bucket plus a small one, or two buckets to be safe.
Do I subtract doors and windows?
Most pros subtract only large openings such as garage doors and big windows. The pieces cut out of a sheet for a normal door or window are usually waste anyway.