About the drywall calculator
Drywall is sold in sheets, most often 4 feet wide and 8, 10, or 12 feet long. This calculator totals your wall and ceiling area, subtracts large openings, adds waste, and tells you how many sheets of your chosen size to buy.
How to use this calculator
- Add up the length of all walls and enter the height.
- Optionally include the ceiling area.
- Enter the total area of large doors and windows.
- Choose a sheet size and waste allowance.
Worked examples
- Walls: 48 × 8 = 384 sq ft
- Ceiling: 144 sq ft; openings: 36 sq ft
- Surface: 492 sq ft × 1.10 = 541.2
- 4 × 8 sheets: 541.2 ÷ 32 = 16.9
17 sheets of 4 × 8 drywall.
Measurement guidance
Openings
Many installers don’t subtract small openings because the cut-outs become waste anyway. Subtract large openings like wide doorways.
Ceilings
Ceiling drywall is heavy; lifts and helpers make hanging much safer.
Frequently asked questions
Which sheet size is best?
Longer sheets mean fewer joints to tape, but they’re heavier and harder to move into rooms.
How much waste should I allow?
Around 10% is common; rooms with many openings and angles may need more.
Does this include joint compound and tape?
No. Those are estimated separately from the sheet count or square footage.