Drywall Calculator

How many drywall sheets do I need for a 12x12 room?

For a 12x12 room with 8 ft ceilings using 4x8 sheets, you need approximately 16 sheets for walls and ceiling. Wall area: 2 x (12+12) x 8 = 384 sq ft. Ceiling area: 12 x 12 = 144 sq ft. Total: 528 sq ft. Each 4x8 sheet covers 32 sq ft. 528 / 32 = 16.5, round up to 17 sheets including waste.

What is the standard drywall sheet size?

The most common drywall sheet size is 4 feet wide by 8 feet long (4x8), covering 32 sq ft. Other common sizes include 4x10 (40 sq ft), 4x12 (48 sq ft), and 4x14 (56 sq ft). Using longer sheets reduces the number of horizontal joints and speeds up installation.

How much does a sheet of drywall cost in 2026?

As of 2026, a standard 4x8 sheet of 1/2 inch regular drywall costs $15-22. Moisture-resistant (green board) costs $18-28 per sheet. Fire-rated (Type X) costs $20-35 per sheet. Prices vary by region and quantity purchased. Bulk purchases typically receive discounts of 10-20%.

What thickness of drywall should I use?

1/2 inch drywall is standard for most walls and ceilings in residential construction. 5/8 inch (Type X) is required for fire-rated assemblies, garage walls, and ceilings with 24-inch joist spacing. 1/4 inch is used for curved walls or over existing surfaces. 3/8 inch is less common but used in some mobile homes.

Do I need moisture-resistant drywall in a bathroom?

Yes, moisture-resistant drywall (green board or purple board) is recommended for bathrooms, particularly around showers, tubs, and sinks. For shower enclosures, use cement board or a specialized tile backer board. Purple board offers additional mold resistance compared to standard green board.

How do I calculate drywall for a ceiling?

Measure the length and width of the ceiling and multiply to get the area. For a 12x12 room, the ceiling area is 144 sq ft. Divide by the sheet area (e.g., 32 sq ft for 4x8): 144 / 32 = 4.5 sheets, so 5 sheets. Orient sheets perpendicular to the joists for maximum strength.

What is Type X drywall?

Type X drywall is fire-rated drywall (5/8 inch thick) with glass fibers in the core to improve fire resistance. It provides a 1-hour fire rating when properly installed. Building codes often require Type X for garage walls (attached to house), furnace rooms, and multi-family dwelling unit separations.

How much does it cost to drywall a room?

In 2026, drywall installation costs $1.50-3.00 per sq ft for materials and labor. A 12x12 room (528 sq ft total wall and ceiling) costs $800-1,600 for professional installation. Materials (sheets, mud, tape, screws) cost about $300-500. Labor accounts for the remaining cost.

What is the difference between regular and moisture-resistant drywall?

Regular drywall has a paper surface that can absorb moisture and promote mold growth. Moisture-resistant drywall (green board) has a wax-treated paper and water-resistant core. Purple board has added mold inhibitors. Both are better for humid areas but neither is waterproof - tile backer board is needed for wet areas.

How do I hang drywall on ceilings?

Hanging drywall on ceilings is best done with a drywall lift or with an assistant. Use 5/8 inch drywall for ceilings with 24-inch joist spacing. Screw every 7-8 inches along edges and every 12 inches in the field. Stagger joints between sheets and avoid aligning with wall sheet joints.

What tools do I need for drywall installation?

Essential drywall tools include: drywall saw or utility knife for cutting, T-square for straight cuts, drywall screw gun or drill with depth-sensing bit, taping knives (4, 6, and 10-12 inch), mud pan, sanding pole or sponge, corner tools for inside and outside corners, and a drywall lift for ceilings.

How long does drywall mud take to dry?

All-purpose joint compound typically takes 24 hours to dry between coats under normal conditions. Quick-setting compound ("hot mud") dries in 20-90 minutes depending on the formula. Factors affecting drying time include humidity, temperature, thickness of application, and air circulation.

How many coats of mud are needed on drywall?

Three coats of joint compound are standard for drywall finishing. The first coat covers tape and fills joints (bedding coat). The second coat widens the joint (fill coat). The third coat provides a smooth, flat surface (finish coat). Each coat needs to dry completely before sanding and applying the next.

What is the best drywall for basements?

For basements, use moisture-resistant drywall (green or purple board) or mold-resistant drywall. Consider using 5/8 inch for better sag resistance on ceilings. If the basement has a history of flooding, consider cement board or fiber-reinforced gypsum panels, or install drywall with a gap at the bottom.

How do I cut drywall?

Score the paper face with a utility knife along a straightedge, snap the board backward to break the gypsum core, then cut the back paper. For cutouts (outlets, windows), use a drywall saw or rotary tool. A rasp or sanding block smooths rough edges. Always wear a dust mask when cutting or sanding drywall.

What is the difference between tapered and square-edge drywall?

Tapered-edge drywall has recessed long edges designed to accept joint tape and compound for a flat, seamless finish. Square-edge drywall (often used for fire-rated assemblies) has straight edges - joints require more mud to achieve a flat surface. Tapered edge is standard for most installations.

How do I repair a hole in drywall?

Small holes (nail/screw size) can be filled with spackle. Medium holes (up to 6 inches) can be repaired with a drywall patch kit or a self-adhesive mesh patch, covered with joint compound. Large holes require cutting out the damaged area, installing a backer board, cutting a replacement piece, taping, and mudding.

What screws should I use for drywall?

Use 1-1/4 inch coarse-thread drywall screws for 1/2 inch drywall on wood studs. Use 1-5/8 inch screws for 5/8 inch drywall. For metal studs, use fine-thread self-tapping drywall screws. Always use a screw gun with a depth-sensing tip to avoid breaking the paper (dimpling but not tearing).

How do I tape drywall corners?

Inside corners use paper tape folded lengthwise and embedded in joint compound. Apply mud to both sides of the corner, fold the tape, press into the corner with a corner trowel, and cover with a thin layer of mud. Outside corners use metal or plastic corner bead, nailed or screwed in place, then covered with mud.

What is the best drywall for soundproofing?

For soundproofing, use sound-rated drywall (e.g., QuietRock) or double-layer 5/8 inch drywall with acoustic sealant between layers. Adding sound-dampening insulation in the wall cavity and using resilient channels also improve sound transmission ratings. Mass-loaded vinyl can be added between layers.

How do I estimate drywall tape needed?

A standard roll of drywall tape (500 ft) covers approximately 500 linear feet of joints. For a 12x12 room with 8 ft ceilings, estimate about 200-300 linear feet of tape including walls, ceiling, and corners. Always buy extra - tape is inexpensive and running out mid-project is frustrating.

Can I drywall over existing drywall?

Yes, you can install new drywall over existing drywall if the surface is clean, flat, and structurally sound. Use 1/4 inch or 3/8 inch drywall to minimize changes to trim and door frames. Remove loose paint or paper. Use longer screws (1-5/8 to 2 inches) to penetrate the studs. This method adds weight and reduces room size slightly.

What is the best drywall for a garage?

For attached garages, building codes typically require 5/8 inch Type X fire-rated drywall on the ceiling and walls shared with the living space. The garage ceiling should also be 5/8 inch Type X. Use regular 1/2 inch drywall for other garage walls if local code allows.

How do I prevent drywall cracks?

Prevent drywall cracks by using proper fastener spacing, staggering joints, avoiding seams at corners of doors and windows, using expansion joints in long walls, and controlling humidity during and after installation. Use flexible caulk (not joint compound) at the junction of walls and ceilings in new construction.

What is paperless drywall?

Paperless drywall uses fiberglass mat facing instead of paper, making it highly resistant to mold and moisture. The gypsum core is also treated for mold resistance. It is more expensive than standard drywall but recommended for bathrooms, basements, and areas prone to moisture or mold concerns.

How much joint compound do I need per sheet?

A standard 4x8 sheet requires approximately 1-2 pounds of joint compound per coat (3-6 pounds total for three coats). For a room with 16 sheets, you would need 50-100 pounds of joint compound total. Pre-mixed compound comes in 1-gallon (12 lb) and 5-gallon (60 lb) buckets.

What is the best way to sand drywall?

Use a pole sander with 120-150 grit sandpaper for large flat areas. Use a sanding sponge for corners and details. A vacuum attachment or HEPA-filtered drywall sander minimizes dust. Always wear a dust mask or respirator and eye protection. Pole-sanding in a circular motion produces the smoothest finish.

How do I finish drywall without texture?

For a smooth (level 5) finish, apply three coats of joint compound, sanding between each coat. After the third coat, apply a thin skim coat over the entire surface. Sand with fine-grit paper (150-180 grit). Level 5 finish is the highest quality and is recommended for rooms with natural side lighting or high-gloss paint.

What is the R-value of drywall?

Standard 1/2 inch drywall has an R-value of approximately R-0.45. It provides minimal insulation value. Drywalls primary functions are fire resistance, sound control, and providing a finished surface. For insulation, use fiberglass batts, spray foam, or rigid foam in the wall cavity behind the drywall.

Can I install drywall horizontally or vertically?

Horizontal installation (sheets parallel to the floor) is common for walls because it reduces the number of tapered joints and makes taping easier. Vertical installation (sheets perpendicular to the floor) is used for narrow walls, furred-out masonry walls, and when using longer sheets to minimize horizontal joints.

How do I drywall around windows and doors?

Cut drywall to fit around window and door openings, leaving a 1/8 to 1/4 inch gap between the drywall and the frame. Use a drywall saw or jigsaw for curved cuts. Install metal J-bead around openings for a clean edge. The gap is covered by casing trim. Avoid butting drywall tight against frames.

What is lightweight drywall?

Lightweight drywall is made with a specially formulated gypsum core that weighs up to 30% less than standard drywall. It is easier to carry, lift, and install, reducing labor fatigue. Despite being lighter, it offers comparable strength, fire resistance, and sound control. It costs slightly more than standard drywall.