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Blueprint Calc

Drywall Calculator

Count sheets, joint compound, tape, screws, and corner bead for any drywalling project. Supports 4x8 and 4x12 sheets, walls and ceilings, with or without openings.

How much drywall do I need?

Measurements in feet. Defaults to a 12x12 room with ceiling.

You need
  • Drywall sheets
    17 × 4x8 sheets
    477.00 sq ft + 10% waste
  • Joint compound
    2 × 4.5 gal buckets
    ~4.80 gal total
  • Drywall tape
    1 roll (500 ft)
    ~286 linear ft needed
  • Drywall screws
    3 × 1 lb boxes
    ~612 screws total
  • Corner bead
    2 × 8 ft pieces
    2 outside corners

What you'll need to buy

Prices approximate · Links go to retailer search results
Estimated total: ~$312 (materials, before tax)

Product links go to Home Depot search results — pick the best match for your project. Prices shown are rough averages.

How we calculated it

Drywall estimates are almost entirely about square footage — once you have the paintable area, the rest of the materials follow fixed ratios:

  1. Total sq ft = wall area + ceiling area − door/window openings
  2. Sheets = (total sq ft × 1.10 waste) ÷ 32 (4x8) or ÷ 48 (4x12), rounded up
  3. Joint compound ≈ 1 gallon per 100 sq ft through all three coats
  4. Drywall tape ≈ 60 linear feet per 100 sq ft of drywall
  5. Screws ≈ 32 per wall sheet, 40 per ceiling sheet (average 36)

For corner bead, multiply the number of outside corners by the wall height and divide by the standard 8 ft piece length.

Industry assumptions: 10% waste (15%+ for rooms with many angles or openings), 1/2" gypsum for walls and ceilings, 1-1/4" drywall screws (use 1-5/8" for 5/8" rock). Code may require 5/8" Type X drywall for garage-to-living walls, basement ceilings under living space, and shared-wall assemblies — check local requirements.

Drywall sheet count by room size

4 × 8 sheets needed for common square rooms with ceiling, 8 ft walls, 1 door, 2 windows, 10% waste.

Room Wall + ceiling Net sq ft 4 × 8 sheets 4 × 12 sheets
8 × 8 ft 320 sq ft 269 sq ft 10 7
10 × 10 ft 420 sq ft 369 sq ft 13 9
12 × 12 ft 528 sq ft 477 sq ft 17 11
12 × 16 ft 640 sq ft 589 sq ft 21 14
14 × 16 ft 704 sq ft 653 sq ft 23 15
16 × 20 ft 896 sq ft 845 sq ft 30 20
20 × 20 ft 1,040 sq ft 989 sq ft 35 23

Subtract 21 sq ft per door, 15 sq ft per window. 4 × 12 sheets create fewer seams but are harder to handle in rooms under 10 ft wide.

Drywall thickness & type by application

When to pick what, per IRC R702 and manufacturer spec.

Location Minimum thickness Type
Most walls & ceilings 1/2" Standard gypsum
Bathrooms (non-shower walls) 1/2" Moisture-resistant (green board)
Shower / tub surrounds 1/2" Cement board (CBU) or waterproof membrane
Garage-side of house-garage wall 1/2" Standard gypsum (IRC R302.6)
Garage ceiling under habitable room 5/8" Type X fire-rated
Ceilings with joists 24" OC 5/8" Sag-resistant or Type X
Shared walls in multi-family 5/8" Type X
Soundproofed rooms 5/8" ×2 layers Standard + Green Glue between

5/8 in Type X weighs ~50% more than standard 1/2 in. Budget for extra helpers or a drywall lift on ceilings.

Frequently asked questions

How do I calculate drywall for a room?
Measure perimeter times ceiling height for the walls, add length times width for the ceiling, and subtract door and window openings (use 21 sq ft per door, 15 sq ft per average window). Divide by sheet size (32 sq ft for 4x8, 48 for 4x12) and add 10% waste.
How many drywall sheets for a 12x12 room?
A 12x12 room with 8 ft ceilings, ceiling included, 1 door, and 1 window needs about 13 × 4x8 sheets including 10% waste. Swap to 4x12 sheets and you will need about 9 sheets.
4x8 or 4x12 sheets — which is better?
4x12 sheets create fewer seams, which means less taping and smoother walls — pros prefer them. 4x8 sheets are much easier to carry up stairs and maneuver alone. For DIY in rooms under 10 ft wide, 4x8 is the lower-frustration pick.
How much joint compound do I need?
About 1 gallon of all-purpose mud covers 100 sq ft of drywall through all three coats (taping, filling, finishing). For a standard room you will usually go through one 4.5-gallon bucket. Buy extra — running dry mid-coat dries out your pan before you can fix it.
How many screws per sheet of drywall?
Code is typically 32 screws for a 4x8 wall sheet (16" spacing on studs), 40 for a ceiling sheet (more frequent). Plan on about 36 screws per sheet average. A 1 lb box holds roughly 240 screws.
Can I hang drywall horizontally or vertically?
Pros usually hang horizontally — it creates one continuous seam at mid-wall that is easier to tape than multiple vertical seams. Vertical hanging is fine for narrow closet walls. Either way, stagger sheets between walls so seams do not line up across the room.
Do I need drywall tape or mesh tape?
Paper tape is stronger and the industry default for flats and inside corners — use it for all seams. Fiberglass mesh tape is self-adhesive and faster for small patches, but it is weaker in tension and not ideal for long seams. Stick with paper.
How much does it cost to drywall a 12x12 room?
Materials alone: ~$200-250 for a 12x12 room with ceiling (13 sheets at ~$14 each plus mud, tape, screws, corner bead). Hiring a crew adds $1.50-3.50 per sq ft of drywall, so total labor for that room is typically $600-1,400 depending on your market.
Should I use 1/2" or 5/8" drywall?
1/2" is standard for walls and most ceilings. Per IRC R302.6, the garage-to-house wall needs 1/2" gypsum on the garage side — but if there is a habitable room directly above the garage, that garage ceiling jumps to 5/8" Type X (fire-rated). 5/8" is also required in some commercial ceilings and shared-wall assemblies. Always check your local code; some jurisdictions amend IRC defaults.
What is a waste factor and why add 10%?
Cuts, mis-measurements, broken corners, and damaged sheets happen. Adding 10% to your sheet count (15% for rooms with lots of openings or odd angles) keeps you from making a second trip to the store mid-project.

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