Drywall Calculator
Find out how many sheets of drywall to buy for a room — plus rough joint compound, tape, and screw estimates — with a cost estimate.
Length, width & wall height
Estimate only. These figures help you plan how much to buy — they are not engineering or structural advice. Actual needs vary with site conditions, waste, and installation method, so order a little extra and confirm final quantities with your supplier or contractor before you buy or start the job.
Popular room sizes
Jump to a ready-made answer for a common room.
How the drywall calculation works
Find the total surface area to cover, then divide by your sheet size.
Walls = 2 × (length + width) × height. Add length × width for the ceiling.
Multiply by ~1.10 to cover cuts and offcuts around openings.
Surface area with waste ÷ sheet size (32 sq ft for 4 × 8), rounded up.
Plan compound, tape, and screws too — rough estimates are shown in the results.
Sources & assumptions
Frequently asked questions
How many sheets of drywall do I need for a 12x12 room?
A 12 × 12 ft room with 8 ft walls has 384 sq ft of wall, plus 144 sq ft of ceiling = 528 sq ft. With 10% waste that's ~581 sq ft. Using 4 × 8 ft sheets (32 sq ft) you need about 19 sheets.
How do I calculate drywall sheets?
Add up the wall area (perimeter × height) plus the ceiling if you're covering it, add ~10% for waste, then divide by your sheet size — 32 sq ft for a 4 × 8, 48 sq ft for a 4 × 12.
How much joint compound and tape do I need?
As a rough rule, plan for about 1 gallon of ready-mix joint compound per 100 sq ft of drywall, roughly 13 ft of tape per 4×8 sheet, and about 1 screw per square foot. This calculator gives quick planning estimates — buy a little extra.
What size drywall sheet should I use?
4 × 8 ft sheets are easiest to handle for DIY. Larger 4 × 12 ft sheets reduce the number of seams to finish but are heavy and harder to maneuver in tight spaces.