Drywall Calculator
Drywall sheets, screws, tape, and joint compound from wall area and sheet size.
Written by Golam Rabbani, Founder & Lead Engineer
How to use this drywall calculator
- Toggle imperial (ft) or metric (m) for the dimensions.
- Enter the total wall length and wall height for the rooms you are sheeting.
- Enter the number of doors and windows to subtract.
- Tick "Include ceiling" and add room length × width if you are sheeting the ceiling too.
- Pick a sheet size (4×8, 4×10, or 4×12) and a waste %, then press Calculate.
About this drywall calculator
The drywall calculator estimates how many sheets of drywall (also called sheetrock or gypsum board) you need for a room, along with the matching screws, joint tape, and joint compound. It computes net wall area after subtracting door (21 ft² / 1.95 m²) and window (15 ft² / 1.4 m²) openings, optionally adds the ceiling area, applies a waste percentage, and divides by the chosen sheet size: 4 × 8 ft = 32 ft², 4 × 10 ft = 40 ft², or 4 × 12 ft = 48 ft².
Worked example: a 12 ft × 12 ft room with 8 ft ceilings has 48 ft of wall length and 384 ft² of gross wall area. Subtract one door (21 ft²) and two windows (30 ft²) and the net is 333 ft². With the ceiling (144 ft²) included, total is 477 ft². Adding 10% waste gives 525 ft². Dividing by 32 ft² per 4×8 sheet gives 16.4, rounded up to 17 sheets. Companion materials: roughly 525 screws (1 per ft²), 735 linear feet of joint tape (1.4 ft per ft²), and 6 gallons of joint compound (1 gal per 100 ft² for taping plus three finish coats).
Larger sheets (4×10 or 4×12) cut down on joints — fewer joints means less mudding and a cleaner finish — but they are heavier and unwieldy for a single installer. Pros prefer 4×12 for long walls and ceilings; DIYers stick with 4×8 because it fits in a pickup and weighs ~55 lb instead of ~80.
FAQ
- How do I know which sheet size to use?
- 4×8 is the standard DIY pick — easy to transport and lift. 4×12 is the pro choice for long walls because it leaves fewer joints to tape and mud. 4×10 is a middle ground.
- How many screws per drywall sheet?
- About 32 screws per 4×8 sheet (1 per ft²) when fastening to studs at 16″ on-center. The calculator returns the total screw count for your job.
- How much joint compound do I need?
- About 1 US gallon (3.78 L) of pre-mixed joint compound per 100 ft² of drywall, covering taping plus three finish coats. Buy at least one full 5-gallon bucket for any job over 500 ft².
- Is 10% waste enough?
- For rectangular rooms with few openings, 10% is plenty. Bump to 15% for vaulted ceilings, stairwells, or any room where you will have lots of awkward cuts.
- Does this calculator account for corner bead or backing?
- No — it covers sheets, screws, tape, and joint compound. Order metal or paper corner bead separately, one 8-ft length per outside corner.
- Is the calculator free?
- Yes — free, no signup, runs in your browser.