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Drywall Calculator

Calculate how many drywall sheets you need, plus screws, tape, joint compound, and cost estimates.

Reference table

Room LengthTotal Drywall AreaSheets NeededScrews Needed
1194 sq ft (18 m²)7 sheets224 screws
1.5209 sq ft (19 m²)7 sheets224 screws
2224 sq ft (21 m²)8 sheets256 screws
2.5240 sq ft (22 m²)8 sheets256 screws
3255 sq ft (24 m²)8 sheets256 screws
4286 sq ft (27 m²)9 sheets288 screws
5317 sq ft (29 m²)10 sheets320 screws
6348 sq ft (32 m²)11 sheets352 screws
7378 sq ft (35 m²)12 sheets384 screws
8409 sq ft (38 m²)13 sheets416 screws
9440 sq ft (41 m²)14 sheets448 screws
10471 sq ft (44 m²)15 sheets480 screws
12532 sq ft (49 m²)17 sheets544 screws
15625 sq ft (58 m²)20 sheets640 screws
20779 sq ft (72 m²)25 sheets800 screws

💡 Installation Tips

  • Hang ceiling sheets first, then walls — use a drywall lift for ceilings
  • Stagger joints between rows to increase wall strength and reduce cracking
  • Drive screws just below paper surface without breaking through
  • Apply 3 coats of joint compound: tape coat, fill coat, and finish coat

What Is Drywall?

Drywall (also called sheetrock, gypsum board, or plasterboard) is a construction material made of gypsum plaster (calcium sulfate dihydrate, CaSO₄·2H₂O) pressed between two thick sheets of paper. It is the most common interior wall and ceiling material used in North America, having largely replaced traditional lath and plaster since the 1950s. Drywall comes in standard 4-foot-wide panels of varying lengths (8, 10, and 12 feet) and thicknesses (¼", ⅜", ½", and ⅝"). The gypsum core provides fire resistance because when exposed to heat, the water molecules in the gypsum evaporate, slowing the spread of fire. Specialized types include moisture-resistant (green board) for bathrooms and kitchens, fire-rated (Type X) with glass fibers for garages and shared walls, and soundproof varieties with damping compounds for noise reduction between rooms.

How the Drywall Calculator Works

This calculator estimates drywall materials by computing the total wall area (perimeter × height), optionally adding ceiling area (length × width), then subtracting openings for doors and windows. A waste factor (typically 10-15%) is added to account for cuts around outlets, corners, and fitting. The total area is divided by the chosen panel size to determine sheets needed, always rounding up since partial sheets cannot be purchased. From the sheet count, the calculator derives fastener requirements (~32 screws per 4'×8' sheet), joint compound quantity (~1 gallon per 100 sq ft for 3 coats), and tape length based on joint linear footage. Cost estimation multiplies sheet count by your price per sheet and adds optional labor costs, giving you a complete project budget before you visit the hardware store.

Key Considerations

  • Standard ½" drywall is suitable for most wall applications with studs spaced 16" on center. Use ⅝" for ceilings to prevent sagging and for fire-rated assemblies.
  • Moisture-resistant (green board) is NOT waterproof — don't use it in direct wet areas like shower enclosures. Use cement board or Kerdi membrane there instead.
  • Fire-rated Type X drywall is required by most building codes for attached garages, furnace rooms, and shared walls between units in multi-family buildings.
  • Order 10-15% extra material. Complex rooms with many corners, outlets, and angles generate more waste from cuts.
  • Drywall should be stored flat and kept dry. A single ½" 4'×8' sheet weighs about 51 lbs — plan for help lifting and a drywall lift for ceilings.
  • Use coarse-thread drywall screws for wood studs and fine-thread for metal studs. Space screws 12" apart on edges and 16" in the field.

Drywall Types & Uses

  • Regular (White Board): Standard gypsum board for interior walls and ceilings in dry areas. Most economical option for bedrooms, living rooms, and hallways.
  • Moisture-Resistant (Green Board): Contains water-resistant additives in the core and paper. Used in bathrooms, kitchens, laundry rooms — but not shower enclosures.
  • Fire-Rated (Type X): Contains glass fibers for enhanced fire resistance. ⅝" Type X provides 1-hour fire rating. Required in garages and fire-rated assemblies.
  • Soundproof (STC-Rated): Uses viscoelastic polymer between gypsum layers to dampen sound. Ideal for media rooms, bedrooms adjacent to noisy areas, and home offices.
  • Flexible (¼" Bend): Thin gypsum that can bend for curved walls and arches. Usually doubled for strength and requires wetting or scoring before installation.
  • Abuse-Resistant: High-density core with reinforced surface for high-traffic areas like corridors, schools, and commercial spaces. Resists dents and punctures.

Calculation Examples

Step-by-step drywall material estimation

Standard Bedroom (12' × 12' × 8')

  1. Perimeter = 2 × (12 + 12) = 48 ft
  2. Gross wall area = 48 × 8 = 384 sq ft
  3. Subtract 1 door (6.67 × 3 = 20 sq ft) + 2 windows (2 × 3 × 4 = 24 sq ft) = 44 sq ft
  4. Net wall area = 384 − 44 = 340 sq ft
  5. Ceiling area = 12 × 12 = 144 sq ft
  6. Total = 340 + 144 = 484 sq ft
  7. With 10% waste = 484 × 1.10 = 532.4 sq ft
  8. Sheets (4'×8' = 32 sq ft each): ⌈532.4 ÷ 32⌉ = 17 sheets

17 sheets of 4'×8' drywall, ~544 screws, ~6 gal joint compound, ~2 rolls of tape

Garage (24' × 24' × 10') Fire-Rated

  1. Perimeter = 2 × (24 + 24) = 96 ft
  2. Gross wall area = 96 × 10 = 960 sq ft
  3. Subtract 1 door (7 × 3 = 21 sq ft) = 21 sq ft
  4. Net wall area = 960 − 21 = 939 sq ft
  5. Ceiling area = 24 × 24 = 576 sq ft
  6. Total = 939 + 576 = 1,515 sq ft
  7. With 12% waste = 1,515 × 1.12 = 1,696.8 sq ft
  8. Sheets (4'×8' = 32 sq ft each): ⌈1696.8 ÷ 32⌉ = 54 sheets

54 sheets of ⅝" Type X (4'×8'), ~1,728 screws, ~17 gal compound, ~5 rolls of tape

Frequently Asked Questions

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

A 12' × 12' room with 8-foot ceilings, 1 door, and 2 windows needs approximately 17 sheets of standard 4'×8' drywall (including ceiling and 10% waste). Without the ceiling, you'd need about 12 sheets. The exact count depends on your waste factor, number of openings, and panel size chosen.

What type of drywall should I use in a bathroom?

Use moisture-resistant drywall (green board) for bathroom walls and ceilings that are not directly in the shower or tub area. For shower enclosures and tub surrounds, use cement backer board (like Durock or HardieBacker) instead — green board is water-resistant but NOT waterproof and will fail in direct wet areas.

How many drywall screws do I need per sheet?

Plan for approximately 32 screws per 4'×8' sheet (about 1 screw per square foot). Screws should be placed every 12 inches along edges and every 16 inches in the field (center area). For ceilings, you may need slightly more screws — approximately 36 per sheet — because they fight gravity.

What is the difference between Type X and regular drywall?

Type X (fire-rated) drywall contains glass fibers in its gypsum core that hold the board together longer during a fire. A ⅝" Type X sheet provides a 1-hour fire rating, while regular ½" drywall provides about 30 minutes. Building codes require Type X in attached garages, between dwelling units, and in furnace/mechanical rooms.

How much joint compound and tape do I need?

Plan for approximately 1 gallon (3.78 L) of pre-mixed joint compound per 100 square feet of drywall for a 3-coat finish (tape, fill, and skim). A standard 5-gallon bucket covers about 460 sq ft. For tape, one 500-foot roll covers approximately 460 sq ft of installed drywall.

Should I hang drywall vertically or horizontally?

Horizontally is preferred for most residential walls because it reduces the total length of joints to tape and creates a stronger wall. The long horizontal edge (tapered) creates flush joints that are easier to finish. Vertical installation is better for rooms with ceilings over 9 feet or for commercial applications with metal studs.

How much does it cost to drywall a room?

Material costs run $0.40-$0.65 per square foot for standard drywall (about $12-$20 per sheet). Professional installation including hanging, taping, and finishing costs $1.50-$3.00 per square foot. A typical 12×12 bedroom with ceiling costs $350-$600 for materials and $750-$1,500 for professional installation.

What thickness drywall should I use?

Use ½" for standard walls with studs at 16" on center (most common). Use ⅝" for ceilings (prevents sagging), fire-rated assemblies, and walls with studs at 24" on center. Use ¼" for curved walls and repairs over existing surfaces. Use ⅜" for minor re-covering of existing walls.

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