Drywall Calculator
Sheets are just the start. Get the sheet count plus the screws, tape and compound that finish the room.
How it works
- Wall area = (length + width) x 2 x wall height, minus doors and windows
- Ceiling area = length x width (if included)
- Sheets = total area (with waste) / sheet area, rounded UP
- Screws, tape and compound are estimated from the total area using standard finishing rates
Worked example
A 12 ft x 10 ft room with 8 ft walls: walls are 352 sq ft, minus a door (21) and a window (15) leaves 316 sq ft. Add the 120 sq ft ceiling for 436 sq ft. With 10% waste that is 480 sq ft, and at 32 sq ft per 4 x 8 sheet you buy 15 sheets - about $225 at $15 a sheet, plus roughly 580 screws, 5 gallons of compound and 1 roll of tape.
Assumptions to know
- Openings use standard sizes: door about 21 sq ft, window about 15 sq ft (1.9 and 1.4 sq m in metric).
- In metric mode, sheet sizes switch to common 1200 x 2400 mm class sheets - the sheet-size list shows the area used.
- Screw, tape and compound rates are finishing estimates, not exact counts.
Results are planning estimates only. Always check the coverage and instructions on the actual product you buy, and measure your own space carefully before ordering. When in doubt, a little extra material is cheaper than a second trip or a stalled job.
Frequently asked questions
How many drywall sheets do I need for a 12 x 12 room?
A 12 x 12 ft room with 8 ft walls has 384 sq ft of wall and 144 sq ft of ceiling - 528 sq ft total. At 32 sq ft per 4 x 8 sheet that is 17 sheets before waste, and about 18 to 19 with a normal waste allowance and openings subtracted.
Should I use 4 x 8 or 4 x 12 sheets?
Bigger sheets mean fewer joints to tape and finish, but they are heavy and hard to move through hallways and stairs. Most DIY rooms use 4 x 8 sheets for handling, even if it means more taping.
How much joint compound and tape do I need?
This calculator estimates both from the total area: roughly 1 gallon of compound per 100 sq ft and about 1 standard tape roll per 1,000 sq ft. Pros buy a little extra mud - running out mid-coat is no fun.
Do I subtract doors and windows?
Yes for a tighter count, and this calculator does it with standard sizes. Many people skip subtracting small openings and let that area act as their waste allowance instead - either approach works if you are consistent.