Drywall Calculator
Estimate drywall for a room.
Input
Result
What is a Drywall Calculator?
The Drywall Calculator helps you estimate the number of drywall sheets needed for a room, including waste. Just enter your numbers and the tool does the rest — no manual math, no guesswork.
How to calculate Drywall manually (the formula)
The specific formula depends on what you are calculating. The calculator applies the correct equation automatically, but understanding the formula helps you verify the results and adapt them to your own needs.
Example calculation
Enter your values into the calculator and it will produce an instant result. For a step-by-step walkthrough, try different inputs and observe how each one affects the outcome.
Common mistakes
- Not adding waste — Always add 10–15% extra for cuts around doors, windows, and corners.
- Forgetting ceiling sheets — Ceilings are often calculated separately and may need thicker drywall or additional support.
- Using the wrong drywall thickness — ½-inch is standard for walls; ⅝-inch is recommended for fire-rated assemblies.
Frequently asked questions
How many drywall sheets do I need?
Calculate the total wall and ceiling area, then divide by the area of one sheet (32 ft² for a 4×8 sheet). Add 10–15% for waste.
What size drywall should I use?
4×8 ft sheets are standard. Use 4×12 ft sheets for taller walls to reduce horizontal seams.
How do I account for doors and windows?
Subtract half the area of doors and windows from the total wall area for a rough estimate.
How much mud and tape do I need?
A 5-gallon bucket of joint compound covers about 500 ft². One roll of tape covers 250–300 ft.
How many screws per sheet of drywall?
About 32 screws per 4×8 sheet (11 per stud with 4 studs per sheet). Use 1¼-inch screws for ½-inch drywall.
Should I hang drywall horizontally or vertically?
Horizontal hanging is common on walls to reduce seam length. Vertical hanging is standard on ceilings.