Drywall Calculator
Enter the total wall and ceiling area you need to cover to find how many sheets of drywall to buy. A 4×8 sheet covers 32 ft² and a 4×12 sheet covers 48 ft².
How to calculate drywall
Add up the area of every wall and ceiling you're covering (length × height), subtract large openings like doors and windows, then divide by the coverage of one sheet: 32 ft² for a 4×8 panel or 48 ft² for a 4×12. Round up and add about 10% for cuts and waste.
Sheets = Area ft² ÷ Sheet coverage (32 ft² for 4×8, 48 ft² for 4×12)
Worked example
A room with 40 linear feet of 8 ft-high walls (320 ft²).
- Area = 40 × 8 = 320 ft²
- 4×8 sheets = 320 ÷ 32 = 10 sheets
- 4×12 sheets = 320 ÷ 48 = 6.67 → 7 sheets
Result: 10 sheets of 4×8 (or 7 sheets of 4×12)
Frequently asked questions
How many sheets of drywall do I need?
Calculate the total square footage of walls and ceilings, then divide by 32 for 4×8 sheets or 48 for 4×12 sheets. Round up and add 10% for waste. 320 ft² needs about 10 sheets of 4×8.
How many square feet is a sheet of drywall?
A standard 4×8 ft sheet covers 32 square feet. A 4×12 ft sheet covers 48 square feet and creates fewer seams on tall or long walls.
Should I use 4×8 or 4×12 drywall?
4×8 sheets are easier to carry and hang solo. 4×12 sheets cover more area with fewer butt joints, which means less taping and a smoother finish, better if you have help.
How much extra drywall should I buy?
Add 10% for straight rooms and up to 15% for rooms with lots of corners, windows, and doors, to cover cutting waste and mistakes.
Do I subtract doors and windows?
For a tighter estimate, subtract openings larger than about 16 ft² (a door or large window). The built-in 10% waste factor usually absorbs smaller openings.