Drywall Calculator
Calculate how many sheets of drywall you need for walls and ceilings. Enter your room dimensions, number of doors and windows, and sheet size to get an instant material estimate including joint compound and screws.
How to Calculate Drywall
The drywall calculation estimates sheets, joint compound, and screws:
- Calculate wall area: Perimeter (2 x length + 2 x width) x ceiling height.
- Subtract openings: Remove doors (~21 sq ft each) and windows (~12 sq ft each).
- Add ceiling (optional): Room length x room width if drywalling the ceiling.
- Divide by sheet size: Total sq ft / sheet sq ft, then round up to whole sheets.
- Add 10% waste: Extra for cuts, errors, and odd-shaped areas.
Drywall Types
- Regular (White Board): Standard drywall for interior walls and ceilings in dry areas. Most common and least expensive.
- Moisture-Resistant (Green Board): Treated for humidity resistance. Used in bathrooms, kitchens, and laundry rooms (not for direct water exposure).
- Fire-Resistant (Type X): Contains glass fibers for enhanced fire rating. Required in garages, furnace rooms, and between attached garages and living spaces.
- Mold-Resistant (Purple Board): Fiberglass-faced for superior mold and moisture protection. Ideal for basements and high-humidity areas.
Drywall Thickness Guide
- 1/4" (6.35mm): Used for curved walls, arches, and overlaying existing surfaces
- 3/8" (9.5mm): Lightweight option for patching or double-layering
- 1/2" (12.7mm): Standard thickness for walls with studs 16" on center
- 5/8" (15.9mm): Recommended for ceilings (resists sagging), fire-rated walls, and studs 24" on center
Drywall Finishing Levels
- Level 0: No taping or finishing. Used in temporary construction or areas above ceilings.
- Level 1: Joints taped with one coat of compound. Used in concealed areas like attics.
- Level 2: Joints taped and skimmed. Suitable for areas receiving tile or paneling.
- Level 3: Two coats of compound on joints and fasteners. For areas receiving heavy texture.
- Level 4: Three coats of compound, sanded smooth. Standard for most painted walls.
- Level 5: Skim coat over entire surface. Required for glossy paints and critical lighting conditions.
Frequently Asked Questions
How many sheets of drywall do I need for a 12x12 room?
For a 12x12 room with 8-foot ceilings, 1 door, and 2 windows, you need about 12 standard 4x8 sheets for the walls. If you're also covering the ceiling, add 5 more sheets for a total of about 17 sheets (including 10% waste).
What drywall thickness should I use for walls vs ceiling?
Use 1/2 inch (12.7mm) drywall for most walls. For ceilings, use 5/8 inch (15.9mm) drywall, which is stiffer and resists sagging. Fire-rated areas also require 5/8 inch Type X drywall. Use 1/4 inch for curved walls and overlays.
How much joint compound do I need?
Plan for approximately 0.05 pounds of joint compound per square foot of drywall. A 4.5-gallon bucket of pre-mixed joint compound covers roughly 400-500 square feet. For a standard 12x12 room, one bucket is usually sufficient.
How many drywall screws do I need?
Use approximately 32 screws per 4x8 sheet of drywall when studs are 16 inches on center. Screws should be placed every 8 inches along edges and every 12 inches in the field (center of the sheet).
Can I hang drywall by myself?
Walls can be hung solo with a drywall lift or foot lever. Ceilings are very difficult alone and typically require two people or a drywall lift. A standard 4x8 sheet of 1/2" drywall weighs about 57 pounds.