Drywall Calculator — How Many Drywall Sheets Do I Need?
Enter your room size, ceiling height, doors and windows to get the exact number of drywall sheets you need, including the ceiling and waste. No sign-up, no data stored.
Drywall sheets needed
How drywall quantity is calculated
The math is simple and exact — no assumptions to adjust for:
- Wall area = perimeter (2 × (length + width)) × ceiling height.
- Ceiling = length × width, added when you're finishing the ceiling too.
- Openings = doors (≈21 sq ft each) + windows (≈15 sq ft each), subtracted so you don't over-order.
- With waste = net area × (1 + waste%).
- Sheets = area ÷ sheet area, rounded up because you can't buy a fraction of a sheet.
A standard 4×8 sheet covers 32 sq ft. Waste covers cuts around openings, studs, corners, and any mistakes. Straight, simple rooms need less; rooms with many windows and doors need more.
Drywall reference chart
Standard sheet sizes, typical opening areas, and coverage.
Drywall sheet size → area
| Sheet size | Sq ft per sheet |
|---|---|
| 4×8 ft | 32 sq ft |
| 4×10 ft | 40 sq ft |
| 4×12 ft | 48 sq ft |
| 4×16 ft | 64 sq ft |
Typical opening areas
| Opening | Typical area |
|---|---|
| Interior door (with frame) | ≈21 sq ft |
| Window (3×5 ft) | ≈15 sq ft |
| Double door / sliding | ≈32–40 sq ft |
Waste by room
| Room type | Add for waste |
|---|---|
| Simple rectangle | ~5–10% |
| Standard room | ~10% |
| Many openings / odd angles | ~15% |
Last updated: October 2026 · Sheet sizes are standard US drywall dimensions. Door and window areas are typical values; measure yours for exact results. Always confirm with your supplier.
Drywall calculator FAQ
With 8 ft ceilings, walls are 384 sq ft plus a 144 sq ft ceiling = 528 sq ft. Subtract one door (21) and one window (15) = 492 sq ft. Add 10% waste = 541 sq ft, which is about 17 sheets of 4×8 drywall.
A standard 4×8 ft sheet is 32 sq ft. A 4×10 is 40 sq ft, a 4×12 is 48 sq ft, and a 4×16 is 64 sq ft.
Usually the ceiling first, then the walls. Hanging the ceiling first lets the wall sheets support its edges and keeps the seams tighter and easier to finish.
Use 1/2-inch for standard interior walls. Use 5/8-inch for ceilings, fire-rated walls, and garages, where added rigidity and fire resistance matter.
The count depends on how many doors, windows, and openings you subtract, and your waste percent. If your room has closets, niches, or cathedral ceilings, add more waste — it's safer to have a few extra sheets than to run short.