Drywall Calculator

Stop Guessing How Many Sheets of Drywall to Buy

Under-order drywall and you're back at the store mid-project with a half-finished wall; over-order and you're stuck with warped sheets taking up garage space. This calculator takes your room's dimensions, subtracts your doors and windows, and works out exactly how many sheets, how much joint compound, and how much tape and screws you need — with a waste allowance built in for cuts and mistakes.

How to use it

• Enter the room's length, width, and wall height in feet.
• Check "Include ceiling" if you're drywalling the ceiling too, not just the walls.
• Set how many doors and windows the room has — the calculator subtracts their standard area automatically.
• Pick your sheet size (4×8, 4×10, or 4×12) and adjust the waste percentage if you're expecting a lot of cuts around corners or fixtures.
• Add a cost per sheet to see the total material cost, if you want a rough budget.

Real-world use cases

Framing out a basement and need to know how many 4×8 sheets to have delivered before the crew shows up. Patching a single bedroom after a renovation and want to avoid a second trip to the lumberyard. Quoting a small job and need a fast, defensible material estimate to hand a client alongside labor costs.

Frequently asked questions

How much drywall do I need for a 12x12 room?

For a 12×12 room with 8-foot ceilings and one standard door, wall area alone is roughly 368 sq ft after subtracting the door. At 32 sq ft per 4×8 sheet with 10% waste, that's about 13 sheets — enter your exact numbers above for a precise count.

Should I include the ceiling in a drywall calculation?

Only if you're actually drywalling the ceiling. Check the "Include ceiling" box and the room's floor area (length × width) gets added to the total on top of the wall area.

How much joint compound do I need per sheet of drywall?

A common rule of thumb is roughly 1 gallon of joint compound per 100 sq ft of drywall for a standard three-coat finish, which is what this calculator uses. Heavily textured or level-5 finishes will use more.

What size drywall sheet should I buy?

4×8 sheets are the standard for most rooms and are easiest to handle alone. 4×12 sheets cover ceilings and tall walls with fewer seams, which means less taping, but they're heavier and harder to maneuver solo.

How many screws does one sheet of drywall need?

Roughly 1.5 screws per square foot is a standard estimate (about 48 screws for a 4×8 sheet spaced correctly along studs), which is the rate this calculator uses for the total screw count.